Infectious Diseases

Infectious diseases historically have posed major challenges to the operations and health of military forces. In recent conflicts, nonbattle injuries including infections have caused more evacuations than combat trauma.¹ Deployment to endemic regions, poor sanitation, and trauma increase susceptibility to both common and rare infections, many of which have cutaneous manifestations.

Surveillance programs such as the Armed Forces Health Surveillance Division serve a critical role in monitoring outbreaks among deployed personnel.² Cutaneous manifestations of systemic disease often serve as early clinical indicators, especially in settings with limited diagnostic resources. This review describes rarely encountered infectious agents for which US military personnel are at increased risk and outlines management strategies for clinicians practicing in austere environments.

EPIDEMIOLOGIC RISK FACTORS IN MILITARY POPULATIONS

United States military personnel face an elevated risk for infectious diseases when deployed in tropical and subtropical regions where endemic pathogens are prevalent. Exposure to soil, water, and insect vectors facilitates transmission. Direct exposure during combat or training combined with high-density housing, combat-related trauma, and constraints on hygiene access during operations increases infection risk.³

REGION-SPECIFIC PATHOGENS

Middle East

Leishmania species—Leishmania, a protozoa transmitted via sand fly bites, has caused multiple documented outbreaks among US troops in Iraq and Afghanistan, with a reported incidence of 14%.⁴ Leishmaniasis can present as 3 main clinical variants: cutaneous, visceral, and mucocutaneous. Cutaneous leishmaniasis typically manifests as painless ulcers covered with hemorrhagic crusts on exposed regions of the body. While typically self-limited, lesions frequently result in irreversible scarring. Many Leishmania species respond well to antimonials such as sodium stibogluconate. Preventive measures include wearing protective clothing and sleeping inside insecticide-treated bed nets.⁵

Coxiella burnetii—Coxiella burnetii transmits through inhalation of aerosolized particles originating from the urine, feces, birth products, or milk of infected bovine. In 2003, a small number of cases were identified in US service members exposed to livestock while serving in Iraq.⁶ Outbreaks also occurred during World War II, but it is unclear whether they were caused by naturally occurring C burnetii or biowarfare.⁷ Though primarily a systemic illness with severe pneumonia, Q fever may manifest with an associated purpuric or morbilliform rash.⁸ Doxycycline is recommended both for treatment and empiric coverage.⁶

Acinetobacter baumannii—This multidrug-resistant organism is known to infect combat wounds and is associated with nosocomial outbreaks in military hospitals. Studies suggest environmental contamination and health care transmission contribute substantially to outbreaks in military hospitals.⁹ Cutaneous manifestations can include cellulitis with a peau d’orange appearance or necrotizing fasciitis; however, pneumonia and bacteremia have been reported. Prompt culture and antibiotic initiation with debridement are essential for treatment.¹⁰ Antibiotic stewardship and strict infection control are critical to prevent outbreaks and limit resistance.⁹

Africa

Plasmodium species—Malaria remains a life-threatening disease found in tropical and subtropical areas around the world. Despite preventive measures, 30 cases among US service members were reported in 2024.¹¹ Cutaneous findings include purpura fulminans, petechiae, acral necrosis, or reticulated erythema.¹² Service members stationed in endemic areas should take prophylactic antimalarials. Symptoms include fevers, headaches, and malaise, with possible rapid deterioration.¹³

Mycobacterium ulcerans—Mycobacterium ulcerans causes extensive necrotic ulcers—commonly known as Buruli ulcers—which generally begin as a nodule, plaque, papule, or edematous lesion, eventually progressing to extensive ulceration. Despite no documented cases of US personnel contracting Buruli ulcers, those stationed in endemic regions remain at risk. Environmental reservoirs of M ulcerans are unknown, but its DNA has been isolated from water sources.^14,15 These ulcers take months to heal, making wound management and antimycobacterial therapy essential. Primary preventive measures include avoidance of swimming in rivers or agricultural work in endemic areas.¹⁴

Mpox Virus—During the 2022 mpox outbreak, male service members who engaged in sexual activity with other men were at the highest risk, with 88.8% of infected service members reporting this practice.¹⁶ While the virus is endemic to Africa, 89.0% of cases were reported from service members stationed in the United States.¹⁷ Typical infection results in fever, headache, lymphadenopathy, and myalgias, followed by a facial rash that spreads over the body, palms, and soles. Safe-sex practices help prevent transmission, and there is a vaccine available for high-risk patients.¹⁶

Southeast Asia

Leptospira species—Leptospira is an aerobic spirochete found in tropical regions worldwide. Transmission occurs when water contaminated with urine from infected animals exposes humans to the organism. Infection manifests as a mild febrile illness, though approximately 10% of patients develop Weil syndrome, consisting of conjunctival suffusion, jaundice, and acute kidney injury. Treatment and prophylaxis include doxycycline, but severe disease warrants intravenous antibiotics.^17,18 A 2014 outbreak among Marines in Japan highlighted poor prophylactic compliance as a key risk factor.¹⁹ Proper education for those at risk is essential to prevent future outbreaks.

Mycobacterium leprae—Leprosy is an acid-fast mycobacterium that remains endemic in the Pacific Islands and Southeast Asia. Case reports of US service members diagnosed with leprosy exist, though only in patients who emigrated from endemic areas.²⁰ This disease has a spectrum of manifestations depending on the immune response, with tuberculoid leprosy showing a ­cell-mediated (T helper 1) response and lepromatous leprosy having more of a humoral (T helper 2) response.²¹ It manifests with hypopigmented anesthetic macules and peripheral neuropathy. Diagnosis is made by skin biopsy, which shows perineural lymphohistiocytic inflammation and non-necrotizing granulomas.²⁰ The infection typically is curable with a multidrug regimen.²¹

Strongyloides stercoralis—This nematode causes infection by transdermal penetration of bare feet. They then migrate to the lungs where the patient coughs and swallows the nematode into the gastrointestinal tract. Strongyloides stercoralis autoinfect by penetrating the intestinal wall, resulting in chronic digestive, respiratory, and cutaneous symptoms. Worldwide prevalence of S stercoralis infection is estimated to be 10% to 40%, with foreign-born US military members at increased risk compared to the general military population.^22,23 Larva currens may manifest with a pruritic erythematous plaque at the site of penetration that progresses to an intensely pruritic, creeping dermatitis as the nematode migrates under the skin. Avoidance of barefoot soil exposure and treatment with ivermectin are effective preventive and therapeutic measures.²³

South America

Ancylostoma braziliense—Found throughout the subtropical world, this hookworm primarily infects dogs and cats and is found in their stool. Larva currens has a similar manifestation and life cycle to cutaneous larva migrans, but autoinfection does not occur. Transmission occurs similarly to S stercoralis and responds well to oral albendazole or ivermectin; however, the infection is self-limited.²⁴ Military cases have been reported,²⁵ though overall morbidity remains poorly characterized.

Dengue Virus—An arbovirus transmitted by Aedes mosquitoes, dengue remains a major military threat. Service members in the Vietnam War experienced an attack rate as high as 80%.^26,27 Infection often manifests with retro-orbital pain and a morbilliform rash that occurs 2 to 5 days after fever, though severe cases may progress to hemorrhagic dengue with skin petechiae or ecchymosis.²⁸ Immediate intervention is essential in symptomatic patients to prevent life-threatening progression. There are no dengue vaccines approved by the US Food and Drug Administration for adults, thus military personnel in endemic areas remain at risk.²⁷

Trypanosoma cruzi—Chagas disease is transmitted when a reduviid infected with T cruzi bites and defecates on the patient’s skin. A skin nodule (chagoma) or painless eyelid edema (Romaña sign) may appear at the site of parasite entry. Chronic disease may result in dilated cardiomyopathy.²⁹ Several cases of Chagas disease have been reported in South American military operations, including an outbreak in 9 Columbian military personnel.³⁰ Cases in the southwestern United States have recently emerged, emphasizing the need for increased awareness.³¹ Proper insect repellent helps to ward off reduviid bugs. Nifurtimox and benznidazole are the only drugs with proven efficacy against T cruzi.²⁹

Continental United States of America

Coccidioides immitis—The first reported case of coccidiomycosis was described in 1892 in a service member with debilitating masses and ulcers.³² Endemic to arid regions of the western United States, coccidioidomycosis affects military trainees at rates up to 32% annually in high-risk settings.³³ Primary infection occurs in the lungs and may spread hematologically. The fungi prefer dry desert soils, which may aerosolize during military maneuvers. Coccidioidomycosis occasionally causes erythema nodosum, and diffuse infection shows verrucous plaques, ulcers, or abscesses. Dust avoidance and mask wearing are advised for those in endemic regions. Ketoconazole and amphotericin B are the only treatments approved by the US Food and Drug Administration.³² When starting immunosuppressive drugs, clinicians should inquire if patients have previously been stationed in Coccidioides-endemic areas, such as Fort Irwin, California, to avoid reactivation of the fungi.³³

Francisella tularensis—Acquired via ticks or contact with wild animals, tularemia causes an ulceroglandular disease with regional lymphadenopathy. Inoculation requires as few as 10 to 25 organisms; thus it is considered a Category A agent for bioterror.³⁴ Natural outbreaks have occurred during war times, most recently during the civil wars in Bosnia and Kosovo.³⁵ Patients may present with a painful ulcer that enlarges to form a plaque with raised borders. Personnel in wooded areas should use tick precautions and handle wild animals cautiously. Treatment includes gentamicin for severe disease, with tetracyclines effective in mild cases.³⁴

PREVENTION AND MANAGEMENT STRATEGIES IN AUSTERE SETTINGS

For health care professionals practicing in military settings, austere environments can provide a challenge for diagnosis of neglected diseases. Despite a lack of advanced diagnostic tools, practical options can be applied to the diagnostic process; for example, teledermatology is utilized for treatment of service members deployed to remote environments.³⁶

Management of uncommon infectious diseases in military personnel often requires treatments outside those practiced in domestic clinics. Field management may indicate prompt empiric therapy while balancing the risks of overtreatment against those of missed diagnoses³⁷; however, medical evacuation to a higher level of care may be indicated in patients with severe presentations to expedite diagnosis and treatment.³⁸

Prevention remains the primary goal to avoid local outbreaks. Long-sleeved uniforms, DEET (N, ­N-diethyl-meta-toluamide)–based repellents, permethrin-impregnated clothing, and bed nets are effective for vector protection. Prophylactic medications and vaccinations often are provided when personnel are deployed to endemic locations.³⁹

Onsite entomology teams also can provide surveillance of the local insect populations. They may contribute to vector control through insecticide application and environmental modification. The Armed Forces Health Surveillance Division and the Global Emerging Infections Surveillance Program monitor infectious threats in real time to locate any potential outbreaks, guiding operational responses.⁴⁰

FINAL THOUGHTS

Dermatologic signs often provide early evidence of infection in military personnel. With increasing antimicrobial resistance and the emergence of new pathogens, it is imperative for clinicians treating members of the military to recognize cutaneous signs, employ efficient diagnostic strategies, and encourage proactive prevention. A collaborative approach spanning dermatology, infectious disease, and public health is essential to protect the modern service member.

Infectious diseases historically have posed major challenges to the operations and health of military forces. In recent conflicts, nonbattle injuries including infections have caused more evacuations than combat trauma.¹ Deployment to endemic regions, poor sanitation, and trauma increase susceptibility to both common and rare infections, many of which have cutaneous manifestations.

Surveillance programs such as the Armed Forces Health Surveillance Division serve a critical role in monitoring outbreaks among deployed personnel.² Cutaneous manifestations of systemic disease often serve as early clinical indicators, especially in settings with limited diagnostic resources. This review describes rarely encountered infectious agents for which US military personnel are at increased risk and outlines management strategies for clinicians practicing in austere environments.

EPIDEMIOLOGIC RISK FACTORS IN MILITARY POPULATIONS

United States military personnel face an elevated risk for infectious diseases when deployed in tropical and subtropical regions where endemic pathogens are prevalent. Exposure to soil, water, and insect vectors facilitates transmission. Direct exposure during combat or training combined with high-density housing, combat-related trauma, and constraints on hygiene access during operations increases infection risk.³

REGION-SPECIFIC PATHOGENS

Middle East

Leishmania species—Leishmania, a protozoa transmitted via sand fly bites, has caused multiple documented outbreaks among US troops in Iraq and Afghanistan, with a reported incidence of 14%.⁴ Leishmaniasis can present as 3 main clinical variants: cutaneous, visceral, and mucocutaneous. Cutaneous leishmaniasis typically manifests as painless ulcers covered with hemorrhagic crusts on exposed regions of the body. While typically self-limited, lesions frequently result in irreversible scarring. Many Leishmania species respond well to antimonials such as sodium stibogluconate. Preventive measures include wearing protective clothing and sleeping inside insecticide-treated bed nets.⁵

Coxiella burnetii—Coxiella burnetii transmits through inhalation of aerosolized particles originating from the urine, feces, birth products, or milk of infected bovine. In 2003, a small number of cases were identified in US service members exposed to livestock while serving in Iraq.⁶ Outbreaks also occurred during World War II, but it is unclear whether they were caused by naturally occurring C burnetii or biowarfare.⁷ Though primarily a systemic illness with severe pneumonia, Q fever may manifest with an associated purpuric or morbilliform rash.⁸ Doxycycline is recommended both for treatment and empiric coverage.⁶

Acinetobacter baumannii—This multidrug-resistant organism is known to infect combat wounds and is associated with nosocomial outbreaks in military hospitals. Studies suggest environmental contamination and health care transmission contribute substantially to outbreaks in military hospitals.⁹ Cutaneous manifestations can include cellulitis with a peau d’orange appearance or necrotizing fasciitis; however, pneumonia and bacteremia have been reported. Prompt culture and antibiotic initiation with debridement are essential for treatment.¹⁰ Antibiotic stewardship and strict infection control are critical to prevent outbreaks and limit resistance.⁹

Africa

Plasmodium species—Malaria remains a life-threatening disease found in tropical and subtropical areas around the world. Despite preventive measures, 30 cases among US service members were reported in 2024.¹¹ Cutaneous findings include purpura fulminans, petechiae, acral necrosis, or reticulated erythema.¹² Service members stationed in endemic areas should take prophylactic antimalarials. Symptoms include fevers, headaches, and malaise, with possible rapid deterioration.¹³

Mycobacterium ulcerans—Mycobacterium ulcerans causes extensive necrotic ulcers—commonly known as Buruli ulcers—which generally begin as a nodule, plaque, papule, or edematous lesion, eventually progressing to extensive ulceration. Despite no documented cases of US personnel contracting Buruli ulcers, those stationed in endemic regions remain at risk. Environmental reservoirs of M ulcerans are unknown, but its DNA has been isolated from water sources.^14,15 These ulcers take months to heal, making wound management and antimycobacterial therapy essential. Primary preventive measures include avoidance of swimming in rivers or agricultural work in endemic areas.¹⁴

Mpox Virus—During the 2022 mpox outbreak, male service members who engaged in sexual activity with other men were at the highest risk, with 88.8% of infected service members reporting this practice.¹⁶ While the virus is endemic to Africa, 89.0% of cases were reported from service members stationed in the United States.¹⁷ Typical infection results in fever, headache, lymphadenopathy, and myalgias, followed by a facial rash that spreads over the body, palms, and soles. Safe-sex practices help prevent transmission, and there is a vaccine available for high-risk patients.¹⁶

Southeast Asia

Leptospira species—Leptospira is an aerobic spirochete found in tropical regions worldwide. Transmission occurs when water contaminated with urine from infected animals exposes humans to the organism. Infection manifests as a mild febrile illness, though approximately 10% of patients develop Weil syndrome, consisting of conjunctival suffusion, jaundice, and acute kidney injury. Treatment and prophylaxis include doxycycline, but severe disease warrants intravenous antibiotics.^17,18 A 2014 outbreak among Marines in Japan highlighted poor prophylactic compliance as a key risk factor.¹⁹ Proper education for those at risk is essential to prevent future outbreaks.

Mycobacterium leprae—Leprosy is an acid-fast mycobacterium that remains endemic in the Pacific Islands and Southeast Asia. Case reports of US service members diagnosed with leprosy exist, though only in patients who emigrated from endemic areas.²⁰ This disease has a spectrum of manifestations depending on the immune response, with tuberculoid leprosy showing a ­cell-mediated (T helper 1) response and lepromatous leprosy having more of a humoral (T helper 2) response.²¹ It manifests with hypopigmented anesthetic macules and peripheral neuropathy. Diagnosis is made by skin biopsy, which shows perineural lymphohistiocytic inflammation and non-necrotizing granulomas.²⁰ The infection typically is curable with a multidrug regimen.²¹

Strongyloides stercoralis—This nematode causes infection by transdermal penetration of bare feet. They then migrate to the lungs where the patient coughs and swallows the nematode into the gastrointestinal tract. Strongyloides stercoralis autoinfect by penetrating the intestinal wall, resulting in chronic digestive, respiratory, and cutaneous symptoms. Worldwide prevalence of S stercoralis infection is estimated to be 10% to 40%, with foreign-born US military members at increased risk compared to the general military population.^22,23 Larva currens may manifest with a pruritic erythematous plaque at the site of penetration that progresses to an intensely pruritic, creeping dermatitis as the nematode migrates under the skin. Avoidance of barefoot soil exposure and treatment with ivermectin are effective preventive and therapeutic measures.²³

South America

Ancylostoma braziliense—Found throughout the subtropical world, this hookworm primarily infects dogs and cats and is found in their stool. Larva currens has a similar manifestation and life cycle to cutaneous larva migrans, but autoinfection does not occur. Transmission occurs similarly to S stercoralis and responds well to oral albendazole or ivermectin; however, the infection is self-limited.²⁴ Military cases have been reported,²⁵ though overall morbidity remains poorly characterized.

Dengue Virus—An arbovirus transmitted by Aedes mosquitoes, dengue remains a major military threat. Service members in the Vietnam War experienced an attack rate as high as 80%.^26,27 Infection often manifests with retro-orbital pain and a morbilliform rash that occurs 2 to 5 days after fever, though severe cases may progress to hemorrhagic dengue with skin petechiae or ecchymosis.²⁸ Immediate intervention is essential in symptomatic patients to prevent life-threatening progression. There are no dengue vaccines approved by the US Food and Drug Administration for adults, thus military personnel in endemic areas remain at risk.²⁷

Trypanosoma cruzi—Chagas disease is transmitted when a reduviid infected with T cruzi bites and defecates on the patient’s skin. A skin nodule (chagoma) or painless eyelid edema (Romaña sign) may appear at the site of parasite entry. Chronic disease may result in dilated cardiomyopathy.²⁹ Several cases of Chagas disease have been reported in South American military operations, including an outbreak in 9 Columbian military personnel.³⁰ Cases in the southwestern United States have recently emerged, emphasizing the need for increased awareness.³¹ Proper insect repellent helps to ward off reduviid bugs. Nifurtimox and benznidazole are the only drugs with proven efficacy against T cruzi.²⁹

Continental United States of America

Coccidioides immitis—The first reported case of coccidiomycosis was described in 1892 in a service member with debilitating masses and ulcers.³² Endemic to arid regions of the western United States, coccidioidomycosis affects military trainees at rates up to 32% annually in high-risk settings.³³ Primary infection occurs in the lungs and may spread hematologically. The fungi prefer dry desert soils, which may aerosolize during military maneuvers. Coccidioidomycosis occasionally causes erythema nodosum, and diffuse infection shows verrucous plaques, ulcers, or abscesses. Dust avoidance and mask wearing are advised for those in endemic regions. Ketoconazole and amphotericin B are the only treatments approved by the US Food and Drug Administration.³² When starting immunosuppressive drugs, clinicians should inquire if patients have previously been stationed in Coccidioides-endemic areas, such as Fort Irwin, California, to avoid reactivation of the fungi.³³

Francisella tularensis—Acquired via ticks or contact with wild animals, tularemia causes an ulceroglandular disease with regional lymphadenopathy. Inoculation requires as few as 10 to 25 organisms; thus it is considered a Category A agent for bioterror.³⁴ Natural outbreaks have occurred during war times, most recently during the civil wars in Bosnia and Kosovo.³⁵ Patients may present with a painful ulcer that enlarges to form a plaque with raised borders. Personnel in wooded areas should use tick precautions and handle wild animals cautiously. Treatment includes gentamicin for severe disease, with tetracyclines effective in mild cases.³⁴

PREVENTION AND MANAGEMENT STRATEGIES IN AUSTERE SETTINGS

For health care professionals practicing in military settings, austere environments can provide a challenge for diagnosis of neglected diseases. Despite a lack of advanced diagnostic tools, practical options can be applied to the diagnostic process; for example, teledermatology is utilized for treatment of service members deployed to remote environments.³⁶

Management of uncommon infectious diseases in military personnel often requires treatments outside those practiced in domestic clinics. Field management may indicate prompt empiric therapy while balancing the risks of overtreatment against those of missed diagnoses³⁷; however, medical evacuation to a higher level of care may be indicated in patients with severe presentations to expedite diagnosis and treatment.³⁸

Prevention remains the primary goal to avoid local outbreaks. Long-sleeved uniforms, DEET (N, ­N-diethyl-meta-toluamide)–based repellents, permethrin-impregnated clothing, and bed nets are effective for vector protection. Prophylactic medications and vaccinations often are provided when personnel are deployed to endemic locations.³⁹

Onsite entomology teams also can provide surveillance of the local insect populations. They may contribute to vector control through insecticide application and environmental modification. The Armed Forces Health Surveillance Division and the Global Emerging Infections Surveillance Program monitor infectious threats in real time to locate any potential outbreaks, guiding operational responses.⁴⁰

FINAL THOUGHTS

Dermatologic signs often provide early evidence of infection in military personnel. With increasing antimicrobial resistance and the emergence of new pathogens, it is imperative for clinicians treating members of the military to recognize cutaneous signs, employ efficient diagnostic strategies, and encourage proactive prevention. A collaborative approach spanning dermatology, infectious disease, and public health is essential to protect the modern service member.

Infectious diseases historically have posed major challenges to the operations and health of military forces. In recent conflicts, nonbattle injuries including infections have caused more evacuations than combat trauma.¹ Deployment to endemic regions, poor sanitation, and trauma increase susceptibility to both common and rare infections, many of which have cutaneous manifestations.

Surveillance programs such as the Armed Forces Health Surveillance Division serve a critical role in monitoring outbreaks among deployed personnel.² Cutaneous manifestations of systemic disease often serve as early clinical indicators, especially in settings with limited diagnostic resources. This review describes rarely encountered infectious agents for which US military personnel are at increased risk and outlines management strategies for clinicians practicing in austere environments.

EPIDEMIOLOGIC RISK FACTORS IN MILITARY POPULATIONS

United States military personnel face an elevated risk for infectious diseases when deployed in tropical and subtropical regions where endemic pathogens are prevalent. Exposure to soil, water, and insect vectors facilitates transmission. Direct exposure during combat or training combined with high-density housing, combat-related trauma, and constraints on hygiene access during operations increases infection risk.³

REGION-SPECIFIC PATHOGENS

Middle East

Leishmania species—Leishmania, a protozoa transmitted via sand fly bites, has caused multiple documented outbreaks among US troops in Iraq and Afghanistan, with a reported incidence of 14%.⁴ Leishmaniasis can present as 3 main clinical variants: cutaneous, visceral, and mucocutaneous. Cutaneous leishmaniasis typically manifests as painless ulcers covered with hemorrhagic crusts on exposed regions of the body. While typically self-limited, lesions frequently result in irreversible scarring. Many Leishmania species respond well to antimonials such as sodium stibogluconate. Preventive measures include wearing protective clothing and sleeping inside insecticide-treated bed nets.⁵

Coxiella burnetii—Coxiella burnetii transmits through inhalation of aerosolized particles originating from the urine, feces, birth products, or milk of infected bovine. In 2003, a small number of cases were identified in US service members exposed to livestock while serving in Iraq.⁶ Outbreaks also occurred during World War II, but it is unclear whether they were caused by naturally occurring C burnetii or biowarfare.⁷ Though primarily a systemic illness with severe pneumonia, Q fever may manifest with an associated purpuric or morbilliform rash.⁸ Doxycycline is recommended both for treatment and empiric coverage.⁶

Acinetobacter baumannii—This multidrug-resistant organism is known to infect combat wounds and is associated with nosocomial outbreaks in military hospitals. Studies suggest environmental contamination and health care transmission contribute substantially to outbreaks in military hospitals.⁹ Cutaneous manifestations can include cellulitis with a peau d’orange appearance or necrotizing fasciitis; however, pneumonia and bacteremia have been reported. Prompt culture and antibiotic initiation with debridement are essential for treatment.¹⁰ Antibiotic stewardship and strict infection control are critical to prevent outbreaks and limit resistance.⁹

Africa

Plasmodium species—Malaria remains a life-threatening disease found in tropical and subtropical areas around the world. Despite preventive measures, 30 cases among US service members were reported in 2024.¹¹ Cutaneous findings include purpura fulminans, petechiae, acral necrosis, or reticulated erythema.¹² Service members stationed in endemic areas should take prophylactic antimalarials. Symptoms include fevers, headaches, and malaise, with possible rapid deterioration.¹³

Mycobacterium ulcerans—Mycobacterium ulcerans causes extensive necrotic ulcers—commonly known as Buruli ulcers—which generally begin as a nodule, plaque, papule, or edematous lesion, eventually progressing to extensive ulceration. Despite no documented cases of US personnel contracting Buruli ulcers, those stationed in endemic regions remain at risk. Environmental reservoirs of M ulcerans are unknown, but its DNA has been isolated from water sources.^14,15 These ulcers take months to heal, making wound management and antimycobacterial therapy essential. Primary preventive measures include avoidance of swimming in rivers or agricultural work in endemic areas.¹⁴

Mpox Virus—During the 2022 mpox outbreak, male service members who engaged in sexual activity with other men were at the highest risk, with 88.8% of infected service members reporting this practice.¹⁶ While the virus is endemic to Africa, 89.0% of cases were reported from service members stationed in the United States.¹⁷ Typical infection results in fever, headache, lymphadenopathy, and myalgias, followed by a facial rash that spreads over the body, palms, and soles. Safe-sex practices help prevent transmission, and there is a vaccine available for high-risk patients.¹⁶

Southeast Asia

Leptospira species—Leptospira is an aerobic spirochete found in tropical regions worldwide. Transmission occurs when water contaminated with urine from infected animals exposes humans to the organism. Infection manifests as a mild febrile illness, though approximately 10% of patients develop Weil syndrome, consisting of conjunctival suffusion, jaundice, and acute kidney injury. Treatment and prophylaxis include doxycycline, but severe disease warrants intravenous antibiotics.^17,18 A 2014 outbreak among Marines in Japan highlighted poor prophylactic compliance as a key risk factor.¹⁹ Proper education for those at risk is essential to prevent future outbreaks.

Mycobacterium leprae—Leprosy is an acid-fast mycobacterium that remains endemic in the Pacific Islands and Southeast Asia. Case reports of US service members diagnosed with leprosy exist, though only in patients who emigrated from endemic areas.²⁰ This disease has a spectrum of manifestations depending on the immune response, with tuberculoid leprosy showing a ­cell-mediated (T helper 1) response and lepromatous leprosy having more of a humoral (T helper 2) response.²¹ It manifests with hypopigmented anesthetic macules and peripheral neuropathy. Diagnosis is made by skin biopsy, which shows perineural lymphohistiocytic inflammation and non-necrotizing granulomas.²⁰ The infection typically is curable with a multidrug regimen.²¹

Strongyloides stercoralis—This nematode causes infection by transdermal penetration of bare feet. They then migrate to the lungs where the patient coughs and swallows the nematode into the gastrointestinal tract. Strongyloides stercoralis autoinfect by penetrating the intestinal wall, resulting in chronic digestive, respiratory, and cutaneous symptoms. Worldwide prevalence of S stercoralis infection is estimated to be 10% to 40%, with foreign-born US military members at increased risk compared to the general military population.^22,23 Larva currens may manifest with a pruritic erythematous plaque at the site of penetration that progresses to an intensely pruritic, creeping dermatitis as the nematode migrates under the skin. Avoidance of barefoot soil exposure and treatment with ivermectin are effective preventive and therapeutic measures.²³

South America

Ancylostoma braziliense—Found throughout the subtropical world, this hookworm primarily infects dogs and cats and is found in their stool. Larva currens has a similar manifestation and life cycle to cutaneous larva migrans, but autoinfection does not occur. Transmission occurs similarly to S stercoralis and responds well to oral albendazole or ivermectin; however, the infection is self-limited.²⁴ Military cases have been reported,²⁵ though overall morbidity remains poorly characterized.

Dengue Virus—An arbovirus transmitted by Aedes mosquitoes, dengue remains a major military threat. Service members in the Vietnam War experienced an attack rate as high as 80%.^26,27 Infection often manifests with retro-orbital pain and a morbilliform rash that occurs 2 to 5 days after fever, though severe cases may progress to hemorrhagic dengue with skin petechiae or ecchymosis.²⁸ Immediate intervention is essential in symptomatic patients to prevent life-threatening progression. There are no dengue vaccines approved by the US Food and Drug Administration for adults, thus military personnel in endemic areas remain at risk.²⁷

Trypanosoma cruzi—Chagas disease is transmitted when a reduviid infected with T cruzi bites and defecates on the patient’s skin. A skin nodule (chagoma) or painless eyelid edema (Romaña sign) may appear at the site of parasite entry. Chronic disease may result in dilated cardiomyopathy.²⁹ Several cases of Chagas disease have been reported in South American military operations, including an outbreak in 9 Columbian military personnel.³⁰ Cases in the southwestern United States have recently emerged, emphasizing the need for increased awareness.³¹ Proper insect repellent helps to ward off reduviid bugs. Nifurtimox and benznidazole are the only drugs with proven efficacy against T cruzi.²⁹

Continental United States of America

Coccidioides immitis—The first reported case of coccidiomycosis was described in 1892 in a service member with debilitating masses and ulcers.³² Endemic to arid regions of the western United States, coccidioidomycosis affects military trainees at rates up to 32% annually in high-risk settings.³³ Primary infection occurs in the lungs and may spread hematologically. The fungi prefer dry desert soils, which may aerosolize during military maneuvers. Coccidioidomycosis occasionally causes erythema nodosum, and diffuse infection shows verrucous plaques, ulcers, or abscesses. Dust avoidance and mask wearing are advised for those in endemic regions. Ketoconazole and amphotericin B are the only treatments approved by the US Food and Drug Administration.³² When starting immunosuppressive drugs, clinicians should inquire if patients have previously been stationed in Coccidioides-endemic areas, such as Fort Irwin, California, to avoid reactivation of the fungi.³³

Francisella tularensis—Acquired via ticks or contact with wild animals, tularemia causes an ulceroglandular disease with regional lymphadenopathy. Inoculation requires as few as 10 to 25 organisms; thus it is considered a Category A agent for bioterror.³⁴ Natural outbreaks have occurred during war times, most recently during the civil wars in Bosnia and Kosovo.³⁵ Patients may present with a painful ulcer that enlarges to form a plaque with raised borders. Personnel in wooded areas should use tick precautions and handle wild animals cautiously. Treatment includes gentamicin for severe disease, with tetracyclines effective in mild cases.³⁴

PREVENTION AND MANAGEMENT STRATEGIES IN AUSTERE SETTINGS

For health care professionals practicing in military settings, austere environments can provide a challenge for diagnosis of neglected diseases. Despite a lack of advanced diagnostic tools, practical options can be applied to the diagnostic process; for example, teledermatology is utilized for treatment of service members deployed to remote environments.³⁶

Management of uncommon infectious diseases in military personnel often requires treatments outside those practiced in domestic clinics. Field management may indicate prompt empiric therapy while balancing the risks of overtreatment against those of missed diagnoses³⁷; however, medical evacuation to a higher level of care may be indicated in patients with severe presentations to expedite diagnosis and treatment.³⁸

Prevention remains the primary goal to avoid local outbreaks. Long-sleeved uniforms, DEET (N, ­N-diethyl-meta-toluamide)–based repellents, permethrin-impregnated clothing, and bed nets are effective for vector protection. Prophylactic medications and vaccinations often are provided when personnel are deployed to endemic locations.³⁹

Onsite entomology teams also can provide surveillance of the local insect populations. They may contribute to vector control through insecticide application and environmental modification. The Armed Forces Health Surveillance Division and the Global Emerging Infections Surveillance Program monitor infectious threats in real time to locate any potential outbreaks, guiding operational responses.⁴⁰

FINAL THOUGHTS

Dermatologic signs often provide early evidence of infection in military personnel. With increasing antimicrobial resistance and the emergence of new pathogens, it is imperative for clinicians treating members of the military to recognize cutaneous signs, employ efficient diagnostic strategies, and encourage proactive prevention. A collaborative approach spanning dermatology, infectious disease, and public health is essential to protect the modern service member.

Self-reported penicillin allergies are common, with a prevalence of about 10% of patients, according to the Centers for Disease Control and Prevention (CDC).¹ However, only about 1% of patients have a true immunoglobulin E (IgE)-mediated allergy. This issue is often further complicated by inaccurate classification of nonallergic adverse effects as an allergy, resulting in incomplete allergy documentation in the electronic health record (EHR). The cross-reactivity rate with cephalosporins (Β-lactam antibiotics) in patients reporting a penicillin allergy is < 1%, which suggests that many patients with reported penicillin allergies can safely receive them.² Despite this, patients with self-reported penicillin allergies often receive non–Β-lactam antibiotic agents, which may be associated with an increased risk of adverse drug reactions (ADRs), increased health care costs, and inferior clinical outcomes.³

Several strategies are recommended to assess patients with self-reported penicillin allergies. According to the CDC, evaluating a patient who reports a penicillin or other Β-lactam antibiotic allergy involves 3 steps: (1) obtaining a thorough medical history, including previous exposures to penicillin or other Β-lactam antibiotic; (2) performing a skin test using the penicillin major and minor determinants; and (3) among those who have a negative penicillin skin test, performing an observed oral challenge with 250 mg amoxicillin before proceeding directly to treatment with the indicated Β-lactam therapy.⁴

Most existing clinical guidance for assessing patients with self-reported penicillin allergies stems from site-specific policies and primarily focuses on oral amoxicillin challenges or penicillin skin testing (PST). However, performing these tests may not be feasible at all facilities due to time constraints and lack of allergists. Therefore, alternative strategies are necessary, such as conducting detailed patient interviews. Few studies have evaluated switching to Β-lactam agents following a penicillin allergy interview alone. However, with thorough patient histories and detailed interviews, patients with reported penicillin allergies can safely use Β-lactam antibiotics.⁵ Implementing this procedure provides a cost-savings opportunity by not having to administer additional antibiotics for testing in addition to improving antibiotic stewardship.

The Memphis Veterans Affairs Medical Center (MVAMC) created the Allergy to Β-Lactam Evaluation (ABLE) process to clarify and remove penicillin allergies. The process involves conducting a thorough chart review and patient interview followed by completion of a note template that provides recommendations about patient allergies and Β-lactam prescribing. Mitchell et al found that the pharmacist-led process to be beneficial for addressing Β-lactam allergy clearance.⁶ As a result, the ABLE process was implemented at several other US Department of Veterans Affairs (VA) medical centers (VAMCs). Using the ABLE template, the purpose of this study was to evaluate the impact of a pharmacist-led penicillin allergy initiative on penicillin allergy delabeling with an interview process alone.

Methods

Prior to ABLE process implementation, there were no standardized procedures for documenting allergy histories. ABLE was implemented at the Robley Rex VAMC (RRVAMC) in November 2022. During the interview phase, patients were initially identified during admission via TheraDoc as having either a penicillin allergy or ADR. The infectious disease pharmacist or pharmacy resident interviewed patients with documented penicillin allergies or ADRs using a standardized questionnaire (eAppendix 1). Not all identified patients could be interviewed. Patients currently receiving an antibiotic were prioritized for interviews. Patients were excluded if they declined or were unable to be interviewed, although a patient’s caregiver(s) could be interviewed in person or via telephone, if the patient was not available.

Following the interview, pharmacists used guidance from the ABLE process in addition to a detailed EHR review to determine whether the patient was eligible for an allergy update or removal and/or switch to a Β-lactam antibiotic (Figure). If eligible for modification, the interviewing pharmacist made the necessary changes. A templated process note with patient-specific recommendations was entered into the Computerized Patient Record System (CPRS) and the primary care team attending physician was added as an additional signer to be alerted in the system note (eAppendix 2).

This single-center, retrospective cohort study involved review of CPRS notes and clinical interviews in the interviewed group. Hospitalized patients at the RRVAMC aged ≥ 18 years with a documented penicillin allergy or ADR were included. The historical control group consisted of patients admitted between October 31, 2019, and October 31, 2022, and the intervention group consisted of patients admitted between November 1, 2022, and March 1, 2023. Patients in the historical control group were matched 1:1 to the intervention group for penicillin allergy severity (allergy [IgE-mediated], unknown, adverse effect, severe cutaneous or other non–IgE-mediated reaction) and whether they received a noncarbapenem non–Β-lactam antibiotic.

The primary outcome was the number of patient allergies/ADRs removed or changed on patient profiles regardless of whether their antibiotic regimen was changed. This outcome was further assessed by evaluating the number of patient allergies or ADRs removed or changed on patient profiles with or without a change in antibiotic regimen. Primary outcomes were analyzed using χ² and/ or Fisher exact tests, as appropriate to determine statistically significant differences between the interviewed group and the historical control.

Results

Seventy patients were included: 35 patients in the interviewed group and 35 patients in the historical control group, respectively. Both groups had a mean age of 72 years and predominantly included White male patients (Table 1). Following the interview, the allergy profile was modified for 6 patients (17%) in the interview group vs 0 patients in the control group (P = .03) (Table 2). The primary outcome was analyzed separately regardless of an antibiotic regimen change. There was not a statistically significant difference between groups when assessing patients for change in therapy (P > .99). All 6 patients with an allergy profile modification had no change in antibiotic regimen.

Discussion

This study suggests the ABLE process may be a valuable tool for adjusting penicillin allergies or ADRs within patient EHRs. In the interview group, allergies were modified in 6 (17%) patients while no patients in the control group had allergy modifications. Of the 6 allergy profile modifications, 4 allergy labels were changed from an allergy to an ADR. These patients were cleared to receive future Β-lactam antibiotics after clinicians recognized the lack of a true IgE-mediated allergic reaction. In addition, 2 of the modified allergy profiles removed the allergy designation. Although this represents a small subset of interviewed patients, it illustrates the clinical effectiveness of an interview process alone to remove penicillin allergy designations.

Previous research has assessed the impact of pharmacist intervention on penicillin allergy clarification. Mitchell et al implemented a pharmacist-driven Β-lactam allergy assessment and penicillin allergy clinic (PAC) at the MVAMC with the goal of evaluating its impact on allergy clearance. In their study, clinical pharmacy specialists evaluated patients with Β-lactam allergies, and those deemed eligible were later seen in the PAC. Among the 246 patients evaluated using the Β-lactam allergy assessment alone and who were not seen in the PAC, 25% had their penicillin allergy removed following a detailed assessment.⁶

Song et al evaluated the effectiveness and feasibility of a pharmacist-driven penicillin allergy delabeling pilot program without skin testing or oral challenges. Patients with penicillin allergies were interviewed by a pharmacy resident using a standardized checklist. Among the 66 patients interviewed, 12 (18%) met the criteria for delabeling and consented to removal of their allergy.⁷ The delabeling rates in these 2 studies are similar to the 17% rate of allergy modification in our study, although this study is the only one to compare results to a historical control group.

Harper et al evaluated the impact of a penicillin allergy assessment, including penicillin skin testing and oral amoxicillin challenges, on delabeling penicillin allergies. Pharmacists completed a penicillin allergy assessment and performed penicillin skin testing and/or oral amoxicillin challenges for eligible patients. Of 35 patients, 31 (89%) had their penicillin allergies delabeled in the EHR.⁸ The rate of penicillin allergy delabeling in Harper et al was likely higher than that seen in our study due to the use of oral challenge and skin testing. Regardless, a detailed penicillin allergy interview alone was effective at RRVAMC, resulting in a significant rate of allergy removal or change. This supports the use of detailed penicillin allergy assessments in settings where penicillin skin testing or oral challenges may not be feasible.

Mann et al demonstrated the effectiveness of penicillin allergy assessments in switching eligible patients to Β-lactam antibiotics. Their single-center, prospective study assessed the impact of a pharmacist-driven detailed penicillin allergy interview initiative. Interviews that evaluated potential changes to allergy profiles were conducted with 175 patients. Of these patients, 135 (77.1%) were on antimicrobial therapy and 42 (31.1%) patients receiving therapy met criteria to switch to a noncarbapenem Β-lactam antibiotic. Thirty-one patients (73.8%) switched with no signs or symptoms of intolerance demonstrating that an interview can be a valuable tool for antibiotic optimization, specifically in patients with penicillin allergy.⁹ No patients in our study switched antibiotic therapy, likely because only a small number of patients were eligible for transition to a noncarbapenem Β-lactam antibiotic. In the Mann et al study, non–Β-lactam antibiotics, such as fluoroquinolones and carbapenems, accounted for > 75% of the antibiotics used.

Limitations

The sample size of this study was small and its duration was short. There is a risk for selection bias as not all identified patients were able to be interviewed while admitted, but patients on antibiotics were prioritized as they were most likely to directly benefit during their current admission from a modification of their allergy. Most patients in the study were White and male, which may limit the generalizability of the results. Additionally, recommendations regarding antibiotic changes were primarily communicated to the treatment team based on a templated note in CPRS alone. Therefore, implementation of these recommendations largely relied upon nonverbal communication. Direct pharmacist-physician communication could have led to a larger impact on antimicrobial therapy changes. The interviewer’s participation in daily rounds with time allotted to discuss this topic can be considered in the future to improve these processes.

Conclusions

This study found that the ABLE process identified patients for penicillin allergy delabeling. With the high prevalence of inaccurate penicillin allergy documentation, this tool offers VA health care systems a way to empower pharmacists in allergy clarification, leading to improvements in antibiotic stewardship. Although the sample size was small, the ABLE process may provide a framework for VA clinicians. Future research has the potential to demonstrate the practicality and effectiveness this pharmacist-led penicillin allergy interview process can offer clinicians.

Self-reported penicillin allergies are common, with a prevalence of about 10% of patients, according to the Centers for Disease Control and Prevention (CDC).¹ However, only about 1% of patients have a true immunoglobulin E (IgE)-mediated allergy. This issue is often further complicated by inaccurate classification of nonallergic adverse effects as an allergy, resulting in incomplete allergy documentation in the electronic health record (EHR). The cross-reactivity rate with cephalosporins (Β-lactam antibiotics) in patients reporting a penicillin allergy is < 1%, which suggests that many patients with reported penicillin allergies can safely receive them.² Despite this, patients with self-reported penicillin allergies often receive non–Β-lactam antibiotic agents, which may be associated with an increased risk of adverse drug reactions (ADRs), increased health care costs, and inferior clinical outcomes.³

Several strategies are recommended to assess patients with self-reported penicillin allergies. According to the CDC, evaluating a patient who reports a penicillin or other Β-lactam antibiotic allergy involves 3 steps: (1) obtaining a thorough medical history, including previous exposures to penicillin or other Β-lactam antibiotic; (2) performing a skin test using the penicillin major and minor determinants; and (3) among those who have a negative penicillin skin test, performing an observed oral challenge with 250 mg amoxicillin before proceeding directly to treatment with the indicated Β-lactam therapy.⁴

Most existing clinical guidance for assessing patients with self-reported penicillin allergies stems from site-specific policies and primarily focuses on oral amoxicillin challenges or penicillin skin testing (PST). However, performing these tests may not be feasible at all facilities due to time constraints and lack of allergists. Therefore, alternative strategies are necessary, such as conducting detailed patient interviews. Few studies have evaluated switching to Β-lactam agents following a penicillin allergy interview alone. However, with thorough patient histories and detailed interviews, patients with reported penicillin allergies can safely use Β-lactam antibiotics.⁵ Implementing this procedure provides a cost-savings opportunity by not having to administer additional antibiotics for testing in addition to improving antibiotic stewardship.

The Memphis Veterans Affairs Medical Center (MVAMC) created the Allergy to Β-Lactam Evaluation (ABLE) process to clarify and remove penicillin allergies. The process involves conducting a thorough chart review and patient interview followed by completion of a note template that provides recommendations about patient allergies and Β-lactam prescribing. Mitchell et al found that the pharmacist-led process to be beneficial for addressing Β-lactam allergy clearance.⁶ As a result, the ABLE process was implemented at several other US Department of Veterans Affairs (VA) medical centers (VAMCs). Using the ABLE template, the purpose of this study was to evaluate the impact of a pharmacist-led penicillin allergy initiative on penicillin allergy delabeling with an interview process alone.

Methods

Prior to ABLE process implementation, there were no standardized procedures for documenting allergy histories. ABLE was implemented at the Robley Rex VAMC (RRVAMC) in November 2022. During the interview phase, patients were initially identified during admission via TheraDoc as having either a penicillin allergy or ADR. The infectious disease pharmacist or pharmacy resident interviewed patients with documented penicillin allergies or ADRs using a standardized questionnaire (eAppendix 1). Not all identified patients could be interviewed. Patients currently receiving an antibiotic were prioritized for interviews. Patients were excluded if they declined or were unable to be interviewed, although a patient’s caregiver(s) could be interviewed in person or via telephone, if the patient was not available.

Following the interview, pharmacists used guidance from the ABLE process in addition to a detailed EHR review to determine whether the patient was eligible for an allergy update or removal and/or switch to a Β-lactam antibiotic (Figure). If eligible for modification, the interviewing pharmacist made the necessary changes. A templated process note with patient-specific recommendations was entered into the Computerized Patient Record System (CPRS) and the primary care team attending physician was added as an additional signer to be alerted in the system note (eAppendix 2).

This single-center, retrospective cohort study involved review of CPRS notes and clinical interviews in the interviewed group. Hospitalized patients at the RRVAMC aged ≥ 18 years with a documented penicillin allergy or ADR were included. The historical control group consisted of patients admitted between October 31, 2019, and October 31, 2022, and the intervention group consisted of patients admitted between November 1, 2022, and March 1, 2023. Patients in the historical control group were matched 1:1 to the intervention group for penicillin allergy severity (allergy [IgE-mediated], unknown, adverse effect, severe cutaneous or other non–IgE-mediated reaction) and whether they received a noncarbapenem non–Β-lactam antibiotic.

The primary outcome was the number of patient allergies/ADRs removed or changed on patient profiles regardless of whether their antibiotic regimen was changed. This outcome was further assessed by evaluating the number of patient allergies or ADRs removed or changed on patient profiles with or without a change in antibiotic regimen. Primary outcomes were analyzed using χ² and/ or Fisher exact tests, as appropriate to determine statistically significant differences between the interviewed group and the historical control.

Results

Seventy patients were included: 35 patients in the interviewed group and 35 patients in the historical control group, respectively. Both groups had a mean age of 72 years and predominantly included White male patients (Table 1). Following the interview, the allergy profile was modified for 6 patients (17%) in the interview group vs 0 patients in the control group (P = .03) (Table 2). The primary outcome was analyzed separately regardless of an antibiotic regimen change. There was not a statistically significant difference between groups when assessing patients for change in therapy (P > .99). All 6 patients with an allergy profile modification had no change in antibiotic regimen.

Discussion

This study suggests the ABLE process may be a valuable tool for adjusting penicillin allergies or ADRs within patient EHRs. In the interview group, allergies were modified in 6 (17%) patients while no patients in the control group had allergy modifications. Of the 6 allergy profile modifications, 4 allergy labels were changed from an allergy to an ADR. These patients were cleared to receive future Β-lactam antibiotics after clinicians recognized the lack of a true IgE-mediated allergic reaction. In addition, 2 of the modified allergy profiles removed the allergy designation. Although this represents a small subset of interviewed patients, it illustrates the clinical effectiveness of an interview process alone to remove penicillin allergy designations.

Previous research has assessed the impact of pharmacist intervention on penicillin allergy clarification. Mitchell et al implemented a pharmacist-driven Β-lactam allergy assessment and penicillin allergy clinic (PAC) at the MVAMC with the goal of evaluating its impact on allergy clearance. In their study, clinical pharmacy specialists evaluated patients with Β-lactam allergies, and those deemed eligible were later seen in the PAC. Among the 246 patients evaluated using the Β-lactam allergy assessment alone and who were not seen in the PAC, 25% had their penicillin allergy removed following a detailed assessment.⁶

Song et al evaluated the effectiveness and feasibility of a pharmacist-driven penicillin allergy delabeling pilot program without skin testing or oral challenges. Patients with penicillin allergies were interviewed by a pharmacy resident using a standardized checklist. Among the 66 patients interviewed, 12 (18%) met the criteria for delabeling and consented to removal of their allergy.⁷ The delabeling rates in these 2 studies are similar to the 17% rate of allergy modification in our study, although this study is the only one to compare results to a historical control group.

Harper et al evaluated the impact of a penicillin allergy assessment, including penicillin skin testing and oral amoxicillin challenges, on delabeling penicillin allergies. Pharmacists completed a penicillin allergy assessment and performed penicillin skin testing and/or oral amoxicillin challenges for eligible patients. Of 35 patients, 31 (89%) had their penicillin allergies delabeled in the EHR.⁸ The rate of penicillin allergy delabeling in Harper et al was likely higher than that seen in our study due to the use of oral challenge and skin testing. Regardless, a detailed penicillin allergy interview alone was effective at RRVAMC, resulting in a significant rate of allergy removal or change. This supports the use of detailed penicillin allergy assessments in settings where penicillin skin testing or oral challenges may not be feasible.

Mann et al demonstrated the effectiveness of penicillin allergy assessments in switching eligible patients to Β-lactam antibiotics. Their single-center, prospective study assessed the impact of a pharmacist-driven detailed penicillin allergy interview initiative. Interviews that evaluated potential changes to allergy profiles were conducted with 175 patients. Of these patients, 135 (77.1%) were on antimicrobial therapy and 42 (31.1%) patients receiving therapy met criteria to switch to a noncarbapenem Β-lactam antibiotic. Thirty-one patients (73.8%) switched with no signs or symptoms of intolerance demonstrating that an interview can be a valuable tool for antibiotic optimization, specifically in patients with penicillin allergy.⁹ No patients in our study switched antibiotic therapy, likely because only a small number of patients were eligible for transition to a noncarbapenem Β-lactam antibiotic. In the Mann et al study, non–Β-lactam antibiotics, such as fluoroquinolones and carbapenems, accounted for > 75% of the antibiotics used.

Limitations

The sample size of this study was small and its duration was short. There is a risk for selection bias as not all identified patients were able to be interviewed while admitted, but patients on antibiotics were prioritized as they were most likely to directly benefit during their current admission from a modification of their allergy. Most patients in the study were White and male, which may limit the generalizability of the results. Additionally, recommendations regarding antibiotic changes were primarily communicated to the treatment team based on a templated note in CPRS alone. Therefore, implementation of these recommendations largely relied upon nonverbal communication. Direct pharmacist-physician communication could have led to a larger impact on antimicrobial therapy changes. The interviewer’s participation in daily rounds with time allotted to discuss this topic can be considered in the future to improve these processes.

Conclusions

This study found that the ABLE process identified patients for penicillin allergy delabeling. With the high prevalence of inaccurate penicillin allergy documentation, this tool offers VA health care systems a way to empower pharmacists in allergy clarification, leading to improvements in antibiotic stewardship. Although the sample size was small, the ABLE process may provide a framework for VA clinicians. Future research has the potential to demonstrate the practicality and effectiveness this pharmacist-led penicillin allergy interview process can offer clinicians.

Self-reported penicillin allergies are common, with a prevalence of about 10% of patients, according to the Centers for Disease Control and Prevention (CDC).¹ However, only about 1% of patients have a true immunoglobulin E (IgE)-mediated allergy. This issue is often further complicated by inaccurate classification of nonallergic adverse effects as an allergy, resulting in incomplete allergy documentation in the electronic health record (EHR). The cross-reactivity rate with cephalosporins (Β-lactam antibiotics) in patients reporting a penicillin allergy is < 1%, which suggests that many patients with reported penicillin allergies can safely receive them.² Despite this, patients with self-reported penicillin allergies often receive non–Β-lactam antibiotic agents, which may be associated with an increased risk of adverse drug reactions (ADRs), increased health care costs, and inferior clinical outcomes.³

Several strategies are recommended to assess patients with self-reported penicillin allergies. According to the CDC, evaluating a patient who reports a penicillin or other Β-lactam antibiotic allergy involves 3 steps: (1) obtaining a thorough medical history, including previous exposures to penicillin or other Β-lactam antibiotic; (2) performing a skin test using the penicillin major and minor determinants; and (3) among those who have a negative penicillin skin test, performing an observed oral challenge with 250 mg amoxicillin before proceeding directly to treatment with the indicated Β-lactam therapy.⁴

Most existing clinical guidance for assessing patients with self-reported penicillin allergies stems from site-specific policies and primarily focuses on oral amoxicillin challenges or penicillin skin testing (PST). However, performing these tests may not be feasible at all facilities due to time constraints and lack of allergists. Therefore, alternative strategies are necessary, such as conducting detailed patient interviews. Few studies have evaluated switching to Β-lactam agents following a penicillin allergy interview alone. However, with thorough patient histories and detailed interviews, patients with reported penicillin allergies can safely use Β-lactam antibiotics.⁵ Implementing this procedure provides a cost-savings opportunity by not having to administer additional antibiotics for testing in addition to improving antibiotic stewardship.

The Memphis Veterans Affairs Medical Center (MVAMC) created the Allergy to Β-Lactam Evaluation (ABLE) process to clarify and remove penicillin allergies. The process involves conducting a thorough chart review and patient interview followed by completion of a note template that provides recommendations about patient allergies and Β-lactam prescribing. Mitchell et al found that the pharmacist-led process to be beneficial for addressing Β-lactam allergy clearance.⁶ As a result, the ABLE process was implemented at several other US Department of Veterans Affairs (VA) medical centers (VAMCs). Using the ABLE template, the purpose of this study was to evaluate the impact of a pharmacist-led penicillin allergy initiative on penicillin allergy delabeling with an interview process alone.

Methods

Prior to ABLE process implementation, there were no standardized procedures for documenting allergy histories. ABLE was implemented at the Robley Rex VAMC (RRVAMC) in November 2022. During the interview phase, patients were initially identified during admission via TheraDoc as having either a penicillin allergy or ADR. The infectious disease pharmacist or pharmacy resident interviewed patients with documented penicillin allergies or ADRs using a standardized questionnaire (eAppendix 1). Not all identified patients could be interviewed. Patients currently receiving an antibiotic were prioritized for interviews. Patients were excluded if they declined or were unable to be interviewed, although a patient’s caregiver(s) could be interviewed in person or via telephone, if the patient was not available.

Following the interview, pharmacists used guidance from the ABLE process in addition to a detailed EHR review to determine whether the patient was eligible for an allergy update or removal and/or switch to a Β-lactam antibiotic (Figure). If eligible for modification, the interviewing pharmacist made the necessary changes. A templated process note with patient-specific recommendations was entered into the Computerized Patient Record System (CPRS) and the primary care team attending physician was added as an additional signer to be alerted in the system note (eAppendix 2).

This single-center, retrospective cohort study involved review of CPRS notes and clinical interviews in the interviewed group. Hospitalized patients at the RRVAMC aged ≥ 18 years with a documented penicillin allergy or ADR were included. The historical control group consisted of patients admitted between October 31, 2019, and October 31, 2022, and the intervention group consisted of patients admitted between November 1, 2022, and March 1, 2023. Patients in the historical control group were matched 1:1 to the intervention group for penicillin allergy severity (allergy [IgE-mediated], unknown, adverse effect, severe cutaneous or other non–IgE-mediated reaction) and whether they received a noncarbapenem non–Β-lactam antibiotic.

The primary outcome was the number of patient allergies/ADRs removed or changed on patient profiles regardless of whether their antibiotic regimen was changed. This outcome was further assessed by evaluating the number of patient allergies or ADRs removed or changed on patient profiles with or without a change in antibiotic regimen. Primary outcomes were analyzed using χ² and/ or Fisher exact tests, as appropriate to determine statistically significant differences between the interviewed group and the historical control.

Results

Seventy patients were included: 35 patients in the interviewed group and 35 patients in the historical control group, respectively. Both groups had a mean age of 72 years and predominantly included White male patients (Table 1). Following the interview, the allergy profile was modified for 6 patients (17%) in the interview group vs 0 patients in the control group (P = .03) (Table 2). The primary outcome was analyzed separately regardless of an antibiotic regimen change. There was not a statistically significant difference between groups when assessing patients for change in therapy (P > .99). All 6 patients with an allergy profile modification had no change in antibiotic regimen.

Discussion

This study suggests the ABLE process may be a valuable tool for adjusting penicillin allergies or ADRs within patient EHRs. In the interview group, allergies were modified in 6 (17%) patients while no patients in the control group had allergy modifications. Of the 6 allergy profile modifications, 4 allergy labels were changed from an allergy to an ADR. These patients were cleared to receive future Β-lactam antibiotics after clinicians recognized the lack of a true IgE-mediated allergic reaction. In addition, 2 of the modified allergy profiles removed the allergy designation. Although this represents a small subset of interviewed patients, it illustrates the clinical effectiveness of an interview process alone to remove penicillin allergy designations.

Previous research has assessed the impact of pharmacist intervention on penicillin allergy clarification. Mitchell et al implemented a pharmacist-driven Β-lactam allergy assessment and penicillin allergy clinic (PAC) at the MVAMC with the goal of evaluating its impact on allergy clearance. In their study, clinical pharmacy specialists evaluated patients with Β-lactam allergies, and those deemed eligible were later seen in the PAC. Among the 246 patients evaluated using the Β-lactam allergy assessment alone and who were not seen in the PAC, 25% had their penicillin allergy removed following a detailed assessment.⁶

Song et al evaluated the effectiveness and feasibility of a pharmacist-driven penicillin allergy delabeling pilot program without skin testing or oral challenges. Patients with penicillin allergies were interviewed by a pharmacy resident using a standardized checklist. Among the 66 patients interviewed, 12 (18%) met the criteria for delabeling and consented to removal of their allergy.⁷ The delabeling rates in these 2 studies are similar to the 17% rate of allergy modification in our study, although this study is the only one to compare results to a historical control group.

Harper et al evaluated the impact of a penicillin allergy assessment, including penicillin skin testing and oral amoxicillin challenges, on delabeling penicillin allergies. Pharmacists completed a penicillin allergy assessment and performed penicillin skin testing and/or oral amoxicillin challenges for eligible patients. Of 35 patients, 31 (89%) had their penicillin allergies delabeled in the EHR.⁸ The rate of penicillin allergy delabeling in Harper et al was likely higher than that seen in our study due to the use of oral challenge and skin testing. Regardless, a detailed penicillin allergy interview alone was effective at RRVAMC, resulting in a significant rate of allergy removal or change. This supports the use of detailed penicillin allergy assessments in settings where penicillin skin testing or oral challenges may not be feasible.

Mann et al demonstrated the effectiveness of penicillin allergy assessments in switching eligible patients to Β-lactam antibiotics. Their single-center, prospective study assessed the impact of a pharmacist-driven detailed penicillin allergy interview initiative. Interviews that evaluated potential changes to allergy profiles were conducted with 175 patients. Of these patients, 135 (77.1%) were on antimicrobial therapy and 42 (31.1%) patients receiving therapy met criteria to switch to a noncarbapenem Β-lactam antibiotic. Thirty-one patients (73.8%) switched with no signs or symptoms of intolerance demonstrating that an interview can be a valuable tool for antibiotic optimization, specifically in patients with penicillin allergy.⁹ No patients in our study switched antibiotic therapy, likely because only a small number of patients were eligible for transition to a noncarbapenem Β-lactam antibiotic. In the Mann et al study, non–Β-lactam antibiotics, such as fluoroquinolones and carbapenems, accounted for > 75% of the antibiotics used.

Limitations

The sample size of this study was small and its duration was short. There is a risk for selection bias as not all identified patients were able to be interviewed while admitted, but patients on antibiotics were prioritized as they were most likely to directly benefit during their current admission from a modification of their allergy. Most patients in the study were White and male, which may limit the generalizability of the results. Additionally, recommendations regarding antibiotic changes were primarily communicated to the treatment team based on a templated note in CPRS alone. Therefore, implementation of these recommendations largely relied upon nonverbal communication. Direct pharmacist-physician communication could have led to a larger impact on antimicrobial therapy changes. The interviewer’s participation in daily rounds with time allotted to discuss this topic can be considered in the future to improve these processes.

Conclusions

This study found that the ABLE process identified patients for penicillin allergy delabeling. With the high prevalence of inaccurate penicillin allergy documentation, this tool offers VA health care systems a way to empower pharmacists in allergy clarification, leading to improvements in antibiotic stewardship. Although the sample size was small, the ABLE process may provide a framework for VA clinicians. Future research has the potential to demonstrate the practicality and effectiveness this pharmacist-led penicillin allergy interview process can offer clinicians.

Given its safety profile and bactericidal activity against the predominant organisms causing surgical site infections (SSIs), cefazolin remains the most popular choice for surgical prophylaxis.¹ Cefazolin offers protection against the pathogens most likely to contaminate the surgical site while minimizing inappropriate methicillin- resistant Staphylococcus aureus coverage that occurs with alternatives such as vancomycin and clindamycin. Documented allergies to Β-lactam antibiotics have historically forced clinicians to avoid the use of cephalosporins due to the potential risk of cross-reactivity. True type 1 (immunoglobin E [IgE]-mediated) cross-allergic reactions between penicillin and cephalosporins are rare, and previously reported data indicate cross-reactivity as a result of antibody recognition is more closely related to the side-chain identity rather than the Β-lactam ring.^2,3

About 10% of US patients report having a penicillin allergy; however, < 1% of the population has a true IgE-mediated allergic reaction.⁴ Previous research that has challenged penicillin allergies with cefazolin for surgical prophylaxis has reported minimal rates of allergic reactions.^2-5

In previous trials, patients with a history of delayed skin reactions, such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS), were excluded. Additionally, patients with an allergy to cefazolin including those with urticaria, angioedema, bronchospasm, or anaphylaxis, were excluded from perioperative retrial of cefazolin. Grant et al found that cefazolin can be safely given to patients with IgE-mediated reactions to penicillin and other cephalosporins due to a structurally different side chain.³

In January 2023, the Veteran Health Indiana (VHI) pharmacy team in conjunction with surgery, infectious disease, and anesthesiology, implemented a screening tool as an amendment to perioperative antibiotic guidance to help determine which patients with a documented penicillin allergy could be candidates for perioperative cefazolin. The implemented screening tool (Allergy Clarification for Cefazolin Evidence-Based Prescribing Tool) has been described by Lam et al, who reported that an increased proportion of patients with documented penicillin allergy received cefazolin without more adverse drug reactions (ADRs).⁵ Patients with a Β-lactam allergy were eligible to receive cefazolin unless the ADR was SJS, TEN, or DRESS, or the offending agent was cefazolin and the patient experienced urticaria, angioedema, bronchospasm, or anaphylaxis. If the reaction was not from cefazolin or was unknown, patients were eligible to receive cefazolin (Figure).

To date, minimal data exist to evaluate the incidence of ADRs when cefazolin is given perioperatively to patients with a previously documented penicillin allergy. The purpose of this study was to evaluate the incidence of allergic ADRs in patients who had a documented penicillin allergy and received periprocedural antibiotics.

Methods

This single-center, retrospective chart review used the US Department of Veterans Affairs (VA) Computerized Patient Record System (CPRS) to identify patients with a documented penicillin allergy who underwent an operation and received periprocedural antibiotics between February 1, 2023, and January 31, 2024. This study was reviewed and approved by the Indiana University Health Institutional Review Board and the VHI Research and Development Committee.

Patients were enrolled if they were aged ≥ 18 years, had a documented penicillin allergy, underwent a surgical intervention, and received perioperative antibiotics during the study period. Patients were excluded if they had a documented penicillin allergy resulting in severe delayed skin reactions (ie, SJS, TEN, or DRESS). These criteria produced 197 surgical procedures. Data were collected for each surgical procedure, so patients could be included more than once. Patient history of allergic reaction to penicillin was obtained through CPRS.

The primary endpoint was the percentage of allergic ADRs in patients with penicillin allergies receiving cefazolin perioperatively. Secondary outcomes included the appropriateness of the antibiotic regimen in congruence with American System of Health Pharmacists (ASHP) recommendations, incidence of SSIs within 30 days of the procedure, incidence of ADRs in those with a history of anaphylaxis vs nonanaphylaxis allergy, incidence of allergic reaction requiring pharmacologic and nonpharmacologic interventions, and incidence of acute kidney injury (AKI). AKI was defined as an increase in serum creatinine by ≥ 0.3 mg/dL within 48 hours or an increase in serum creatinine to ≥ 1.5 times baseline.

Demographic data included sex, age, race, preoperative serum creatinine, and postoperative serum creatinine. Anaphylaxis was defined as an acute onset of illness (within minutes to several hours) with involvement of skin, mucosal tissue, or both involving either respiratory compromise or reduced blood pressures. Allergic reactions were defined as facial, tongue, throat, airway, lip, mouth, periorbital, or eye swelling, urticaria, angioedema, dyspnea, anaphylaxis, or a positive penicillin skin test. Additionally, data collected included the description and severity of postprophylactic antibiotic reaction, antibiotic choice, interventions required for the allergic reaction, SSI occurrence, date of SSI, operating specialty, and postoperative change in renal function.

Descriptive statistics, including mean, SD, and percentages were reported for baseline characteristics of the study population. Percentages were used to demonstrate the differences in primary and secondary outcomes for each study group. Fisher exact tests were used for incidence of ADRs in patients with penicillin allergy who received cefazolin and reported incidence of SSIs.

Results

A total of 197 surgical procedures in patients with a documented penicillin allergy were included; 127 procedures used cefazolin perioperatively, 3 procedures used cefazolin plus gentamicin, and 67 procedures used other antibiotics. Most patients were White (n = 160; 81.2%), male (n = 158; 80.2%), and had a mean age of 64.9 years. Urology was the most common surgical specialty (n = 59; 29.9%) (Table 1). Of the 16 patients with documented penicillin anaphylaxis reaction, 8 received cefazolin and 8 received a different antibiotic. A total of 181 patients reported a nonanaphylaxis allergy. One hundred fifty-one patients (68.6%) reported a reaction history of hives, rash, or swelling (Table 2). Patients could report ≥ 1 reaction. The most prevalent antibiotics used were cefazolin, which was used by 130 patients (61.3%), and clindamycin which was used by 33 patients (15.6%) (Table 3). Patients could receive ≥ 1 antibiotic.

For the primary outcome, the incidence of allergic reactions in patients allergic to penicillin, there was no incidence of allergic reactions in either the cefazolin or other group. Given the absence of reactions, no interventions were required.

There were no ADRs in those with history of anaphylaxis or nonanaphylaxis allergy. In the cefazolin group, 126 of 127 surgical procedure regimens (99.2%) were congruent with ASHP recommendations, all 3 surgical procedures regimens in the cefazolin plus gentamicin group were congruent with ASHP recommendations, and 58 of 67 surgical procedure regimens (86.6%) in the other antibiotic group were congruent with ASHP recommendations. None of the 127 patients in the cefazolin group or of the 3 patients in the cefazolin plus gentamicin group reported an SSI, and 3 of 67 patients (4.5%) had an SSI in the other antibiotic group. One procedure that resulted in SSI was not congruent with ASHP recommendations. Twenty-four patients had 2 serum creatinine levels drawn within 48 hours of surgery. One of 12 patients (8.3%) and 0 of 12 patients had an AKI in the cefazolin and other antibiotic group, respectively (Table 4).

Discussion

Implementation of a screening tool at VHI allowed patients with documented penicillin allergy, including anaphylaxis, to receive cefazolin perioperatively. Broad spectrum antibiotics such as vancomycin, clindamycin, and fluoroquinolones are frequently used in patients allergic to penicillin, which can increase health care costs, risk of toxicity, and antimicrobial resistance.⁴ There was no incidence of allergic reactions noted in patients allergic to penicillin who received cefazolin. When comparing the incidence of observed allergic reactions to received perioperative antibiotics in the cefazolin group to previously published literature, no difference in allergy rates (P = .09) was found.³ Most antibiotics administered were congruent with ASHP guideline recommendations, and most patients eligible for cefazolin received it perioperatively.

Similar to this study, Goodman et al concluded that cefazolin appears to be a safe regimen in patients with documented penicillin anaphylactic reaction for surgical prophylaxis with only 1 (0.2%) potential allergic reaction.⁶ Patients who received cefazolin perioperatively had a statistically significant decrease in SSI rates. There were no clinically or statistically significant differences found between the proportion of allergic reactions or ADRs when compared to alternative antibiotics. Lessard et al concluded that a pharmacist-led interdisciplinary collaborative practice agreement increased cefazolin use in patients allergic to penicillin, including those with urticaria and anaphylaxis, with no reported ADRs.⁷ This study further demonstrated the safety of cefazolin use in patients with anaphylaxis to penicillin.

Limitations

This study’s single-center, retrospective design, patient population, and small sample size limit the generalizability of its results. The data collected are dependent on documentation in the chart. No ADRs were reported from the antibiotics patients received perioperatively. When considering safety data, information such as serum creatinine were available only in CPRS and some patients did not receive a postprocedure serum creatinine level. Additionally, this study did not investigate whether there was an increase in preferred preoperative antimicrobial prophylaxis after implementation of this protocol.

Conclusions

The results of this study support the use of cefazolin perioperatively in patients allergic to penicillin, including those with a history of anaphylaxis. Additional research should be conducted to validate data given the low incidence of ADRs. The primary outcome did not reach statistical significance, but the results may be clinically significant from a stewardship and safety perspective. VHI continues to use the screening tool described in this article.

Given its safety profile and bactericidal activity against the predominant organisms causing surgical site infections (SSIs), cefazolin remains the most popular choice for surgical prophylaxis.¹ Cefazolin offers protection against the pathogens most likely to contaminate the surgical site while minimizing inappropriate methicillin- resistant Staphylococcus aureus coverage that occurs with alternatives such as vancomycin and clindamycin. Documented allergies to Β-lactam antibiotics have historically forced clinicians to avoid the use of cephalosporins due to the potential risk of cross-reactivity. True type 1 (immunoglobin E [IgE]-mediated) cross-allergic reactions between penicillin and cephalosporins are rare, and previously reported data indicate cross-reactivity as a result of antibody recognition is more closely related to the side-chain identity rather than the Β-lactam ring.^2,3

About 10% of US patients report having a penicillin allergy; however, < 1% of the population has a true IgE-mediated allergic reaction.⁴ Previous research that has challenged penicillin allergies with cefazolin for surgical prophylaxis has reported minimal rates of allergic reactions.^2-5

In previous trials, patients with a history of delayed skin reactions, such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS), were excluded. Additionally, patients with an allergy to cefazolin including those with urticaria, angioedema, bronchospasm, or anaphylaxis, were excluded from perioperative retrial of cefazolin. Grant et al found that cefazolin can be safely given to patients with IgE-mediated reactions to penicillin and other cephalosporins due to a structurally different side chain.³

In January 2023, the Veteran Health Indiana (VHI) pharmacy team in conjunction with surgery, infectious disease, and anesthesiology, implemented a screening tool as an amendment to perioperative antibiotic guidance to help determine which patients with a documented penicillin allergy could be candidates for perioperative cefazolin. The implemented screening tool (Allergy Clarification for Cefazolin Evidence-Based Prescribing Tool) has been described by Lam et al, who reported that an increased proportion of patients with documented penicillin allergy received cefazolin without more adverse drug reactions (ADRs).⁵ Patients with a Β-lactam allergy were eligible to receive cefazolin unless the ADR was SJS, TEN, or DRESS, or the offending agent was cefazolin and the patient experienced urticaria, angioedema, bronchospasm, or anaphylaxis. If the reaction was not from cefazolin or was unknown, patients were eligible to receive cefazolin (Figure).

To date, minimal data exist to evaluate the incidence of ADRs when cefazolin is given perioperatively to patients with a previously documented penicillin allergy. The purpose of this study was to evaluate the incidence of allergic ADRs in patients who had a documented penicillin allergy and received periprocedural antibiotics.

Methods

This single-center, retrospective chart review used the US Department of Veterans Affairs (VA) Computerized Patient Record System (CPRS) to identify patients with a documented penicillin allergy who underwent an operation and received periprocedural antibiotics between February 1, 2023, and January 31, 2024. This study was reviewed and approved by the Indiana University Health Institutional Review Board and the VHI Research and Development Committee.

Patients were enrolled if they were aged ≥ 18 years, had a documented penicillin allergy, underwent a surgical intervention, and received perioperative antibiotics during the study period. Patients were excluded if they had a documented penicillin allergy resulting in severe delayed skin reactions (ie, SJS, TEN, or DRESS). These criteria produced 197 surgical procedures. Data were collected for each surgical procedure, so patients could be included more than once. Patient history of allergic reaction to penicillin was obtained through CPRS.

The primary endpoint was the percentage of allergic ADRs in patients with penicillin allergies receiving cefazolin perioperatively. Secondary outcomes included the appropriateness of the antibiotic regimen in congruence with American System of Health Pharmacists (ASHP) recommendations, incidence of SSIs within 30 days of the procedure, incidence of ADRs in those with a history of anaphylaxis vs nonanaphylaxis allergy, incidence of allergic reaction requiring pharmacologic and nonpharmacologic interventions, and incidence of acute kidney injury (AKI). AKI was defined as an increase in serum creatinine by ≥ 0.3 mg/dL within 48 hours or an increase in serum creatinine to ≥ 1.5 times baseline.

Demographic data included sex, age, race, preoperative serum creatinine, and postoperative serum creatinine. Anaphylaxis was defined as an acute onset of illness (within minutes to several hours) with involvement of skin, mucosal tissue, or both involving either respiratory compromise or reduced blood pressures. Allergic reactions were defined as facial, tongue, throat, airway, lip, mouth, periorbital, or eye swelling, urticaria, angioedema, dyspnea, anaphylaxis, or a positive penicillin skin test. Additionally, data collected included the description and severity of postprophylactic antibiotic reaction, antibiotic choice, interventions required for the allergic reaction, SSI occurrence, date of SSI, operating specialty, and postoperative change in renal function.

Descriptive statistics, including mean, SD, and percentages were reported for baseline characteristics of the study population. Percentages were used to demonstrate the differences in primary and secondary outcomes for each study group. Fisher exact tests were used for incidence of ADRs in patients with penicillin allergy who received cefazolin and reported incidence of SSIs.

Results

A total of 197 surgical procedures in patients with a documented penicillin allergy were included; 127 procedures used cefazolin perioperatively, 3 procedures used cefazolin plus gentamicin, and 67 procedures used other antibiotics. Most patients were White (n = 160; 81.2%), male (n = 158; 80.2%), and had a mean age of 64.9 years. Urology was the most common surgical specialty (n = 59; 29.9%) (Table 1). Of the 16 patients with documented penicillin anaphylaxis reaction, 8 received cefazolin and 8 received a different antibiotic. A total of 181 patients reported a nonanaphylaxis allergy. One hundred fifty-one patients (68.6%) reported a reaction history of hives, rash, or swelling (Table 2). Patients could report ≥ 1 reaction. The most prevalent antibiotics used were cefazolin, which was used by 130 patients (61.3%), and clindamycin which was used by 33 patients (15.6%) (Table 3). Patients could receive ≥ 1 antibiotic.

For the primary outcome, the incidence of allergic reactions in patients allergic to penicillin, there was no incidence of allergic reactions in either the cefazolin or other group. Given the absence of reactions, no interventions were required.

There were no ADRs in those with history of anaphylaxis or nonanaphylaxis allergy. In the cefazolin group, 126 of 127 surgical procedure regimens (99.2%) were congruent with ASHP recommendations, all 3 surgical procedures regimens in the cefazolin plus gentamicin group were congruent with ASHP recommendations, and 58 of 67 surgical procedure regimens (86.6%) in the other antibiotic group were congruent with ASHP recommendations. None of the 127 patients in the cefazolin group or of the 3 patients in the cefazolin plus gentamicin group reported an SSI, and 3 of 67 patients (4.5%) had an SSI in the other antibiotic group. One procedure that resulted in SSI was not congruent with ASHP recommendations. Twenty-four patients had 2 serum creatinine levels drawn within 48 hours of surgery. One of 12 patients (8.3%) and 0 of 12 patients had an AKI in the cefazolin and other antibiotic group, respectively (Table 4).

Discussion

Implementation of a screening tool at VHI allowed patients with documented penicillin allergy, including anaphylaxis, to receive cefazolin perioperatively. Broad spectrum antibiotics such as vancomycin, clindamycin, and fluoroquinolones are frequently used in patients allergic to penicillin, which can increase health care costs, risk of toxicity, and antimicrobial resistance.⁴ There was no incidence of allergic reactions noted in patients allergic to penicillin who received cefazolin. When comparing the incidence of observed allergic reactions to received perioperative antibiotics in the cefazolin group to previously published literature, no difference in allergy rates (P = .09) was found.³ Most antibiotics administered were congruent with ASHP guideline recommendations, and most patients eligible for cefazolin received it perioperatively.

Similar to this study, Goodman et al concluded that cefazolin appears to be a safe regimen in patients with documented penicillin anaphylactic reaction for surgical prophylaxis with only 1 (0.2%) potential allergic reaction.⁶ Patients who received cefazolin perioperatively had a statistically significant decrease in SSI rates. There were no clinically or statistically significant differences found between the proportion of allergic reactions or ADRs when compared to alternative antibiotics. Lessard et al concluded that a pharmacist-led interdisciplinary collaborative practice agreement increased cefazolin use in patients allergic to penicillin, including those with urticaria and anaphylaxis, with no reported ADRs.⁷ This study further demonstrated the safety of cefazolin use in patients with anaphylaxis to penicillin.

Limitations

This study’s single-center, retrospective design, patient population, and small sample size limit the generalizability of its results. The data collected are dependent on documentation in the chart. No ADRs were reported from the antibiotics patients received perioperatively. When considering safety data, information such as serum creatinine were available only in CPRS and some patients did not receive a postprocedure serum creatinine level. Additionally, this study did not investigate whether there was an increase in preferred preoperative antimicrobial prophylaxis after implementation of this protocol.

Conclusions

The results of this study support the use of cefazolin perioperatively in patients allergic to penicillin, including those with a history of anaphylaxis. Additional research should be conducted to validate data given the low incidence of ADRs. The primary outcome did not reach statistical significance, but the results may be clinically significant from a stewardship and safety perspective. VHI continues to use the screening tool described in this article.

Given its safety profile and bactericidal activity against the predominant organisms causing surgical site infections (SSIs), cefazolin remains the most popular choice for surgical prophylaxis.¹ Cefazolin offers protection against the pathogens most likely to contaminate the surgical site while minimizing inappropriate methicillin- resistant Staphylococcus aureus coverage that occurs with alternatives such as vancomycin and clindamycin. Documented allergies to Β-lactam antibiotics have historically forced clinicians to avoid the use of cephalosporins due to the potential risk of cross-reactivity. True type 1 (immunoglobin E [IgE]-mediated) cross-allergic reactions between penicillin and cephalosporins are rare, and previously reported data indicate cross-reactivity as a result of antibody recognition is more closely related to the side-chain identity rather than the Β-lactam ring.^2,3

About 10% of US patients report having a penicillin allergy; however, < 1% of the population has a true IgE-mediated allergic reaction.⁴ Previous research that has challenged penicillin allergies with cefazolin for surgical prophylaxis has reported minimal rates of allergic reactions.^2-5

In previous trials, patients with a history of delayed skin reactions, such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS), were excluded. Additionally, patients with an allergy to cefazolin including those with urticaria, angioedema, bronchospasm, or anaphylaxis, were excluded from perioperative retrial of cefazolin. Grant et al found that cefazolin can be safely given to patients with IgE-mediated reactions to penicillin and other cephalosporins due to a structurally different side chain.³

In January 2023, the Veteran Health Indiana (VHI) pharmacy team in conjunction with surgery, infectious disease, and anesthesiology, implemented a screening tool as an amendment to perioperative antibiotic guidance to help determine which patients with a documented penicillin allergy could be candidates for perioperative cefazolin. The implemented screening tool (Allergy Clarification for Cefazolin Evidence-Based Prescribing Tool) has been described by Lam et al, who reported that an increased proportion of patients with documented penicillin allergy received cefazolin without more adverse drug reactions (ADRs).⁵ Patients with a Β-lactam allergy were eligible to receive cefazolin unless the ADR was SJS, TEN, or DRESS, or the offending agent was cefazolin and the patient experienced urticaria, angioedema, bronchospasm, or anaphylaxis. If the reaction was not from cefazolin or was unknown, patients were eligible to receive cefazolin (Figure).

To date, minimal data exist to evaluate the incidence of ADRs when cefazolin is given perioperatively to patients with a previously documented penicillin allergy. The purpose of this study was to evaluate the incidence of allergic ADRs in patients who had a documented penicillin allergy and received periprocedural antibiotics.

Methods

This single-center, retrospective chart review used the US Department of Veterans Affairs (VA) Computerized Patient Record System (CPRS) to identify patients with a documented penicillin allergy who underwent an operation and received periprocedural antibiotics between February 1, 2023, and January 31, 2024. This study was reviewed and approved by the Indiana University Health Institutional Review Board and the VHI Research and Development Committee.

Patients were enrolled if they were aged ≥ 18 years, had a documented penicillin allergy, underwent a surgical intervention, and received perioperative antibiotics during the study period. Patients were excluded if they had a documented penicillin allergy resulting in severe delayed skin reactions (ie, SJS, TEN, or DRESS). These criteria produced 197 surgical procedures. Data were collected for each surgical procedure, so patients could be included more than once. Patient history of allergic reaction to penicillin was obtained through CPRS.

The primary endpoint was the percentage of allergic ADRs in patients with penicillin allergies receiving cefazolin perioperatively. Secondary outcomes included the appropriateness of the antibiotic regimen in congruence with American System of Health Pharmacists (ASHP) recommendations, incidence of SSIs within 30 days of the procedure, incidence of ADRs in those with a history of anaphylaxis vs nonanaphylaxis allergy, incidence of allergic reaction requiring pharmacologic and nonpharmacologic interventions, and incidence of acute kidney injury (AKI). AKI was defined as an increase in serum creatinine by ≥ 0.3 mg/dL within 48 hours or an increase in serum creatinine to ≥ 1.5 times baseline.

Demographic data included sex, age, race, preoperative serum creatinine, and postoperative serum creatinine. Anaphylaxis was defined as an acute onset of illness (within minutes to several hours) with involvement of skin, mucosal tissue, or both involving either respiratory compromise or reduced blood pressures. Allergic reactions were defined as facial, tongue, throat, airway, lip, mouth, periorbital, or eye swelling, urticaria, angioedema, dyspnea, anaphylaxis, or a positive penicillin skin test. Additionally, data collected included the description and severity of postprophylactic antibiotic reaction, antibiotic choice, interventions required for the allergic reaction, SSI occurrence, date of SSI, operating specialty, and postoperative change in renal function.

Descriptive statistics, including mean, SD, and percentages were reported for baseline characteristics of the study population. Percentages were used to demonstrate the differences in primary and secondary outcomes for each study group. Fisher exact tests were used for incidence of ADRs in patients with penicillin allergy who received cefazolin and reported incidence of SSIs.

Results

A total of 197 surgical procedures in patients with a documented penicillin allergy were included; 127 procedures used cefazolin perioperatively, 3 procedures used cefazolin plus gentamicin, and 67 procedures used other antibiotics. Most patients were White (n = 160; 81.2%), male (n = 158; 80.2%), and had a mean age of 64.9 years. Urology was the most common surgical specialty (n = 59; 29.9%) (Table 1). Of the 16 patients with documented penicillin anaphylaxis reaction, 8 received cefazolin and 8 received a different antibiotic. A total of 181 patients reported a nonanaphylaxis allergy. One hundred fifty-one patients (68.6%) reported a reaction history of hives, rash, or swelling (Table 2). Patients could report ≥ 1 reaction. The most prevalent antibiotics used were cefazolin, which was used by 130 patients (61.3%), and clindamycin which was used by 33 patients (15.6%) (Table 3). Patients could receive ≥ 1 antibiotic.

For the primary outcome, the incidence of allergic reactions in patients allergic to penicillin, there was no incidence of allergic reactions in either the cefazolin or other group. Given the absence of reactions, no interventions were required.

There were no ADRs in those with history of anaphylaxis or nonanaphylaxis allergy. In the cefazolin group, 126 of 127 surgical procedure regimens (99.2%) were congruent with ASHP recommendations, all 3 surgical procedures regimens in the cefazolin plus gentamicin group were congruent with ASHP recommendations, and 58 of 67 surgical procedure regimens (86.6%) in the other antibiotic group were congruent with ASHP recommendations. None of the 127 patients in the cefazolin group or of the 3 patients in the cefazolin plus gentamicin group reported an SSI, and 3 of 67 patients (4.5%) had an SSI in the other antibiotic group. One procedure that resulted in SSI was not congruent with ASHP recommendations. Twenty-four patients had 2 serum creatinine levels drawn within 48 hours of surgery. One of 12 patients (8.3%) and 0 of 12 patients had an AKI in the cefazolin and other antibiotic group, respectively (Table 4).

Discussion

Implementation of a screening tool at VHI allowed patients with documented penicillin allergy, including anaphylaxis, to receive cefazolin perioperatively. Broad spectrum antibiotics such as vancomycin, clindamycin, and fluoroquinolones are frequently used in patients allergic to penicillin, which can increase health care costs, risk of toxicity, and antimicrobial resistance.⁴ There was no incidence of allergic reactions noted in patients allergic to penicillin who received cefazolin. When comparing the incidence of observed allergic reactions to received perioperative antibiotics in the cefazolin group to previously published literature, no difference in allergy rates (P = .09) was found.³ Most antibiotics administered were congruent with ASHP guideline recommendations, and most patients eligible for cefazolin received it perioperatively.

Similar to this study, Goodman et al concluded that cefazolin appears to be a safe regimen in patients with documented penicillin anaphylactic reaction for surgical prophylaxis with only 1 (0.2%) potential allergic reaction.⁶ Patients who received cefazolin perioperatively had a statistically significant decrease in SSI rates. There were no clinically or statistically significant differences found between the proportion of allergic reactions or ADRs when compared to alternative antibiotics. Lessard et al concluded that a pharmacist-led interdisciplinary collaborative practice agreement increased cefazolin use in patients allergic to penicillin, including those with urticaria and anaphylaxis, with no reported ADRs.⁷ This study further demonstrated the safety of cefazolin use in patients with anaphylaxis to penicillin.

Limitations

This study’s single-center, retrospective design, patient population, and small sample size limit the generalizability of its results. The data collected are dependent on documentation in the chart. No ADRs were reported from the antibiotics patients received perioperatively. When considering safety data, information such as serum creatinine were available only in CPRS and some patients did not receive a postprocedure serum creatinine level. Additionally, this study did not investigate whether there was an increase in preferred preoperative antimicrobial prophylaxis after implementation of this protocol.

Conclusions

The results of this study support the use of cefazolin perioperatively in patients allergic to penicillin, including those with a history of anaphylaxis. Additional research should be conducted to validate data given the low incidence of ADRs. The primary outcome did not reach statistical significance, but the results may be clinically significant from a stewardship and safety perspective. VHI continues to use the screening tool described in this article.

THE DIAGNOSIS: Cutaneous Leishmaniasis

The biopsy results revealed amastigotes at the periphery of parasitized histiocytes, consistent with a diagnosis of cutaneous leishmaniasis. Polymerase chain reaction analysis revealed Leishmania guyanensis species complex, which includes both L guyanensis and Leishmania panamensis. In this case of disseminated cutaneous leishmaniasis (Figure 1), our patient received a prolonged course of systemic therapy with oral miltefosine 50 mg 3 times daily. At the most recent follow-up appointment, she showed ongoing resolution of ulcerations, subcutaneous plaques, and lymphadenopathy on the trunk and face, but development of subcutaneous nodules continued on the arms and legs. At the next follow-up, physical examination revealed that the lesions slowly started to fade.

Leishmania species are parasites transmitted by bites of female sand flies, which belong to the genera Phlebotomus (Old World, Eastern Hemisphere) and Lutzomyia (New World, Western Hemisphere) genera.¹ Leishmania species have a complex life cycle, propagating within human macrophages, ultimately leading to cutaneous, mucocutaneous, and visceral disease manifestations.² Cutaneous leishmaniasis manifests classically as scattered, painless, slow-healing ulcers.³ A biopsy taken from the edge of a cutaneous ulcer for hematoxylin and eosin processing is recommended for initial diagnosis, and subsequent polymerase chain reaction of the sample is required for speciation, which guides therapeutic options.^4,5 Classic hematoxylin and eosin and Giemsa stain findings include amastigotes lining the edges of parasitized histiocytes (Figure 2).

Systemic treatment options include sodium stibogluconate, amphotericin B, pentamidine, paromomycin, miltefosine, and azole antifungals.^2,5 Geography often plays a critical role in selecting treatment options due to resistance rates of individual Leishmania species; for example, paromomycin compounds are more effective for cutaneous disease caused by Leishmania major than Leishmania tropica. Miltefosine is not effective for treating Leishmania braziliensis which can be acquired outside Guatemala, and higher doses of amphotericin B are recommended for visceral disease from East Africa.^2,5 In patients with cutaneous leishmaniasis caused by L guyanensis, miltefosine remains a first-line option due to its oral formulation and long half-life within organisms, though there is a risk for teratogenicity.² Amphotericin B remains the most effective treatment for visceral leishmaniasis and can be used off label to treat mucocutaneous disease or when cutaneous disease is refractory to other treatment options.³

Given the potential of L guyanensis to progress to mucocutaneous disease, monitoring for mucosal involvement should be performed at regular intervals for 6 months to 1 year.² Treatment may be considered efficacious if no new skin lesions occur after 4 to 6 weeks of therapy; existing skin lesions should be re-epithelializing and reduced by 50% in size, with most cutaneous disease adequately controlled after 3 months of therapy.²

THE DIAGNOSIS: Cutaneous Leishmaniasis

The biopsy results revealed amastigotes at the periphery of parasitized histiocytes, consistent with a diagnosis of cutaneous leishmaniasis. Polymerase chain reaction analysis revealed Leishmania guyanensis species complex, which includes both L guyanensis and Leishmania panamensis. In this case of disseminated cutaneous leishmaniasis (Figure 1), our patient received a prolonged course of systemic therapy with oral miltefosine 50 mg 3 times daily. At the most recent follow-up appointment, she showed ongoing resolution of ulcerations, subcutaneous plaques, and lymphadenopathy on the trunk and face, but development of subcutaneous nodules continued on the arms and legs. At the next follow-up, physical examination revealed that the lesions slowly started to fade.

Leishmania species are parasites transmitted by bites of female sand flies, which belong to the genera Phlebotomus (Old World, Eastern Hemisphere) and Lutzomyia (New World, Western Hemisphere) genera.¹ Leishmania species have a complex life cycle, propagating within human macrophages, ultimately leading to cutaneous, mucocutaneous, and visceral disease manifestations.² Cutaneous leishmaniasis manifests classically as scattered, painless, slow-healing ulcers.³ A biopsy taken from the edge of a cutaneous ulcer for hematoxylin and eosin processing is recommended for initial diagnosis, and subsequent polymerase chain reaction of the sample is required for speciation, which guides therapeutic options.^4,5 Classic hematoxylin and eosin and Giemsa stain findings include amastigotes lining the edges of parasitized histiocytes (Figure 2).

Systemic treatment options include sodium stibogluconate, amphotericin B, pentamidine, paromomycin, miltefosine, and azole antifungals.^2,5 Geography often plays a critical role in selecting treatment options due to resistance rates of individual Leishmania species; for example, paromomycin compounds are more effective for cutaneous disease caused by Leishmania major than Leishmania tropica. Miltefosine is not effective for treating Leishmania braziliensis which can be acquired outside Guatemala, and higher doses of amphotericin B are recommended for visceral disease from East Africa.^2,5 In patients with cutaneous leishmaniasis caused by L guyanensis, miltefosine remains a first-line option due to its oral formulation and long half-life within organisms, though there is a risk for teratogenicity.² Amphotericin B remains the most effective treatment for visceral leishmaniasis and can be used off label to treat mucocutaneous disease or when cutaneous disease is refractory to other treatment options.³

Given the potential of L guyanensis to progress to mucocutaneous disease, monitoring for mucosal involvement should be performed at regular intervals for 6 months to 1 year.² Treatment may be considered efficacious if no new skin lesions occur after 4 to 6 weeks of therapy; existing skin lesions should be re-epithelializing and reduced by 50% in size, with most cutaneous disease adequately controlled after 3 months of therapy.²

THE DIAGNOSIS: Cutaneous Leishmaniasis

The biopsy results revealed amastigotes at the periphery of parasitized histiocytes, consistent with a diagnosis of cutaneous leishmaniasis. Polymerase chain reaction analysis revealed Leishmania guyanensis species complex, which includes both L guyanensis and Leishmania panamensis. In this case of disseminated cutaneous leishmaniasis (Figure 1), our patient received a prolonged course of systemic therapy with oral miltefosine 50 mg 3 times daily. At the most recent follow-up appointment, she showed ongoing resolution of ulcerations, subcutaneous plaques, and lymphadenopathy on the trunk and face, but development of subcutaneous nodules continued on the arms and legs. At the next follow-up, physical examination revealed that the lesions slowly started to fade.

Leishmania species are parasites transmitted by bites of female sand flies, which belong to the genera Phlebotomus (Old World, Eastern Hemisphere) and Lutzomyia (New World, Western Hemisphere) genera.¹ Leishmania species have a complex life cycle, propagating within human macrophages, ultimately leading to cutaneous, mucocutaneous, and visceral disease manifestations.² Cutaneous leishmaniasis manifests classically as scattered, painless, slow-healing ulcers.³ A biopsy taken from the edge of a cutaneous ulcer for hematoxylin and eosin processing is recommended for initial diagnosis, and subsequent polymerase chain reaction of the sample is required for speciation, which guides therapeutic options.^4,5 Classic hematoxylin and eosin and Giemsa stain findings include amastigotes lining the edges of parasitized histiocytes (Figure 2).

Systemic treatment options include sodium stibogluconate, amphotericin B, pentamidine, paromomycin, miltefosine, and azole antifungals.^2,5 Geography often plays a critical role in selecting treatment options due to resistance rates of individual Leishmania species; for example, paromomycin compounds are more effective for cutaneous disease caused by Leishmania major than Leishmania tropica. Miltefosine is not effective for treating Leishmania braziliensis which can be acquired outside Guatemala, and higher doses of amphotericin B are recommended for visceral disease from East Africa.^2,5 In patients with cutaneous leishmaniasis caused by L guyanensis, miltefosine remains a first-line option due to its oral formulation and long half-life within organisms, though there is a risk for teratogenicity.² Amphotericin B remains the most effective treatment for visceral leishmaniasis and can be used off label to treat mucocutaneous disease or when cutaneous disease is refractory to other treatment options.³

Given the potential of L guyanensis to progress to mucocutaneous disease, monitoring for mucosal involvement should be performed at regular intervals for 6 months to 1 year.² Treatment may be considered efficacious if no new skin lesions occur after 4 to 6 weeks of therapy; existing skin lesions should be re-epithelializing and reduced by 50% in size, with most cutaneous disease adequately controlled after 3 months of therapy.²

France has authorized Ricimed, the first antibody-based treatment specifically indicated for acute ricin intoxication, providing clinicians with a targeted option beyond supportive care for exposure to one of the most lethal naturally occurring toxins.

Fabentech is a French biopharmaceutical company specializing in medical countermeasures against biological threats and infectious diseases.

The polyclonal antibody technology used in the development of Ricimed has received marketing authorization in France as a treatment for ricin poisoning. Ricin is a highly toxic natural substance that can cause death within hours to a few days of exposure.

Supported by the Ministry of Armed Forces and Veterans Affairs (Directorate General of Armaments [DGA] and Armed Forces Health Service) in France, Ricimed is the first approved antidote for ricin poisoning, a condition for which treatment was previously limited to supportive measures alone.

Historical Incident

One incident, in particular, remains etched in espionage history. On September 7, 1978 in London during the Cold War, Bulgarian dissident writer Georgi Markov, living in exile, was struck by the umbrella of a passer-by while waiting at a bus stop. He felt a slight sting. Four days later, he died in the hospital due to a sudden and unexplained illness. An autopsy revealed that he had been poisoned by a tiny metal pellet implanted at the tip of an umbrella containing ricin, a lethal toxin. The legend of the “Bulgarian umbrella,” later invoked in other assassination attempts, was born.

Since then, although Markov remains the only known individual to have been killed by ricin poisoning, this theoretically extremely toxic substance, which can be manufactured relatively easily from castor beans, a widely available plant, has continued to fascinate authors of thrillers and spy novels.

Numerous works of fiction depict characters who succumb to ricin poisoning. The toxin is notably portrayed as a favored weapon of the main character in the hit television series Breaking Bad.

However, ricin is not confined to the realm of science fiction. For several years, authorities in various countries have feared that extremist groups could carry out attacks using ricin. The threat has been taken particularly seriously since 2018, when a clandestine ricin laboratory operated by members of the Islamic State was dismantled in Germany. Since then, several similar attack plots have been thwarted.

This context triggered a race among major powers to develop an effective antidote as quickly as possible. In this effort, Fabentech has risen to a challenge.

“Having demonstrated its ability to target and then neutralize ricin before it causes irreparable damage, Ricimed is a treatment that works based on polyclonal antibodies and compensates for the absence of a vaccine or specific treatment,” Fabentech said in a press release.

The polyclonal antibody technology used by Fabentech offers potential for the development of antidotes against bioterrorist attacks and for the treatment of many infectious diseases.

Ricimed contributed to the deployment of a European health shield against intentional biological threats in France.

Military Backing

Speaking to Le Figaro, France’s oldest national newspaper, Fabentech CEO Sébastien Iva explained that ricin disrupts the body by halting cell function, while noting several other drug candidates in development at the firm.

Typically, the lungs sustain fatal damage. Our treatment interrupts this toxic process. In animals administered the antidote, we observed pulmonary function recovery, allowing survival.

Given that the possibility of terrorist attacks using ricin is considered a national security issue, Fabentech benefited from the support by the Ministry of the Armed Forces and the DGA and lasted nearly a decade of research and development work.

The granting of marketing authorisation was also supported by the French Armed Forces and welcomed by the French Minister of the Armed Forces, Catherine Vautrin, who previously served as France’s Minister of Labour, Health, and Solidarity.

“Supporting the development of companies in France capable of manufacturing antidotes against certain biological agents helps guarantee the operational superiority of our armed forces. Developing and producing such drugs when they do not yet exist on the market is also serving the nation and the public interest,” she said.

Although the threat posed by ricin remains hypothetical, Fabentech reports a strong interest from potential clients, with many countries seeking protection against possible bioterrorist attacks.

The DGA had already placed an order for several doses of Ricimed for deployment in France. For optimal effectiveness, the antidote must be administered within 6 hours of poisoning. Iva confirmed that multiple countries had already expressed interest in acquiring the antidote.

This story was translated from JIM, part of the Medscape Professional Network.

A version of this article first appeared on Medscape.com.

France has authorized Ricimed, the first antibody-based treatment specifically indicated for acute ricin intoxication, providing clinicians with a targeted option beyond supportive care for exposure to one of the most lethal naturally occurring toxins.

Fabentech is a French biopharmaceutical company specializing in medical countermeasures against biological threats and infectious diseases.

The polyclonal antibody technology used in the development of Ricimed has received marketing authorization in France as a treatment for ricin poisoning. Ricin is a highly toxic natural substance that can cause death within hours to a few days of exposure.

Supported by the Ministry of Armed Forces and Veterans Affairs (Directorate General of Armaments [DGA] and Armed Forces Health Service) in France, Ricimed is the first approved antidote for ricin poisoning, a condition for which treatment was previously limited to supportive measures alone.

Historical Incident

One incident, in particular, remains etched in espionage history. On September 7, 1978 in London during the Cold War, Bulgarian dissident writer Georgi Markov, living in exile, was struck by the umbrella of a passer-by while waiting at a bus stop. He felt a slight sting. Four days later, he died in the hospital due to a sudden and unexplained illness. An autopsy revealed that he had been poisoned by a tiny metal pellet implanted at the tip of an umbrella containing ricin, a lethal toxin. The legend of the “Bulgarian umbrella,” later invoked in other assassination attempts, was born.

Since then, although Markov remains the only known individual to have been killed by ricin poisoning, this theoretically extremely toxic substance, which can be manufactured relatively easily from castor beans, a widely available plant, has continued to fascinate authors of thrillers and spy novels.

Numerous works of fiction depict characters who succumb to ricin poisoning. The toxin is notably portrayed as a favored weapon of the main character in the hit television series Breaking Bad.

However, ricin is not confined to the realm of science fiction. For several years, authorities in various countries have feared that extremist groups could carry out attacks using ricin. The threat has been taken particularly seriously since 2018, when a clandestine ricin laboratory operated by members of the Islamic State was dismantled in Germany. Since then, several similar attack plots have been thwarted.

This context triggered a race among major powers to develop an effective antidote as quickly as possible. In this effort, Fabentech has risen to a challenge.

“Having demonstrated its ability to target and then neutralize ricin before it causes irreparable damage, Ricimed is a treatment that works based on polyclonal antibodies and compensates for the absence of a vaccine or specific treatment,” Fabentech said in a press release.

The polyclonal antibody technology used by Fabentech offers potential for the development of antidotes against bioterrorist attacks and for the treatment of many infectious diseases.

Ricimed contributed to the deployment of a European health shield against intentional biological threats in France.

Military Backing

Speaking to Le Figaro, France’s oldest national newspaper, Fabentech CEO Sébastien Iva explained that ricin disrupts the body by halting cell function, while noting several other drug candidates in development at the firm.

Typically, the lungs sustain fatal damage. Our treatment interrupts this toxic process. In animals administered the antidote, we observed pulmonary function recovery, allowing survival.

Given that the possibility of terrorist attacks using ricin is considered a national security issue, Fabentech benefited from the support by the Ministry of the Armed Forces and the DGA and lasted nearly a decade of research and development work.

The granting of marketing authorisation was also supported by the French Armed Forces and welcomed by the French Minister of the Armed Forces, Catherine Vautrin, who previously served as France’s Minister of Labour, Health, and Solidarity.

“Supporting the development of companies in France capable of manufacturing antidotes against certain biological agents helps guarantee the operational superiority of our armed forces. Developing and producing such drugs when they do not yet exist on the market is also serving the nation and the public interest,” she said.

Although the threat posed by ricin remains hypothetical, Fabentech reports a strong interest from potential clients, with many countries seeking protection against possible bioterrorist attacks.

The DGA had already placed an order for several doses of Ricimed for deployment in France. For optimal effectiveness, the antidote must be administered within 6 hours of poisoning. Iva confirmed that multiple countries had already expressed interest in acquiring the antidote.

This story was translated from JIM, part of the Medscape Professional Network.

A version of this article first appeared on Medscape.com.

France has authorized Ricimed, the first antibody-based treatment specifically indicated for acute ricin intoxication, providing clinicians with a targeted option beyond supportive care for exposure to one of the most lethal naturally occurring toxins.

Fabentech is a French biopharmaceutical company specializing in medical countermeasures against biological threats and infectious diseases.

The polyclonal antibody technology used in the development of Ricimed has received marketing authorization in France as a treatment for ricin poisoning. Ricin is a highly toxic natural substance that can cause death within hours to a few days of exposure.

Supported by the Ministry of Armed Forces and Veterans Affairs (Directorate General of Armaments [DGA] and Armed Forces Health Service) in France, Ricimed is the first approved antidote for ricin poisoning, a condition for which treatment was previously limited to supportive measures alone.

Historical Incident

One incident, in particular, remains etched in espionage history. On September 7, 1978 in London during the Cold War, Bulgarian dissident writer Georgi Markov, living in exile, was struck by the umbrella of a passer-by while waiting at a bus stop. He felt a slight sting. Four days later, he died in the hospital due to a sudden and unexplained illness. An autopsy revealed that he had been poisoned by a tiny metal pellet implanted at the tip of an umbrella containing ricin, a lethal toxin. The legend of the “Bulgarian umbrella,” later invoked in other assassination attempts, was born.

Since then, although Markov remains the only known individual to have been killed by ricin poisoning, this theoretically extremely toxic substance, which can be manufactured relatively easily from castor beans, a widely available plant, has continued to fascinate authors of thrillers and spy novels.

Numerous works of fiction depict characters who succumb to ricin poisoning. The toxin is notably portrayed as a favored weapon of the main character in the hit television series Breaking Bad.

However, ricin is not confined to the realm of science fiction. For several years, authorities in various countries have feared that extremist groups could carry out attacks using ricin. The threat has been taken particularly seriously since 2018, when a clandestine ricin laboratory operated by members of the Islamic State was dismantled in Germany. Since then, several similar attack plots have been thwarted.

This context triggered a race among major powers to develop an effective antidote as quickly as possible. In this effort, Fabentech has risen to a challenge.

“Having demonstrated its ability to target and then neutralize ricin before it causes irreparable damage, Ricimed is a treatment that works based on polyclonal antibodies and compensates for the absence of a vaccine or specific treatment,” Fabentech said in a press release.

The polyclonal antibody technology used by Fabentech offers potential for the development of antidotes against bioterrorist attacks and for the treatment of many infectious diseases.

Ricimed contributed to the deployment of a European health shield against intentional biological threats in France.

Military Backing

Speaking to Le Figaro, France’s oldest national newspaper, Fabentech CEO Sébastien Iva explained that ricin disrupts the body by halting cell function, while noting several other drug candidates in development at the firm.

Typically, the lungs sustain fatal damage. Our treatment interrupts this toxic process. In animals administered the antidote, we observed pulmonary function recovery, allowing survival.

Given that the possibility of terrorist attacks using ricin is considered a national security issue, Fabentech benefited from the support by the Ministry of the Armed Forces and the DGA and lasted nearly a decade of research and development work.

The granting of marketing authorisation was also supported by the French Armed Forces and welcomed by the French Minister of the Armed Forces, Catherine Vautrin, who previously served as France’s Minister of Labour, Health, and Solidarity.

“Supporting the development of companies in France capable of manufacturing antidotes against certain biological agents helps guarantee the operational superiority of our armed forces. Developing and producing such drugs when they do not yet exist on the market is also serving the nation and the public interest,” she said.

Although the threat posed by ricin remains hypothetical, Fabentech reports a strong interest from potential clients, with many countries seeking protection against possible bioterrorist attacks.

The DGA had already placed an order for several doses of Ricimed for deployment in France. For optimal effectiveness, the antidote must be administered within 6 hours of poisoning. Iva confirmed that multiple countries had already expressed interest in acquiring the antidote.

This story was translated from JIM, part of the Medscape Professional Network.

A version of this article first appeared on Medscape.com.

Candida is a common commensal organism of human skin and mucous membranes. Candidiasis of the skin and nails is caused by overgrowth of Candida species due to excess skin moisture, skin barrier disruption, or immunosuppression. Candidiasis of the skin manifests as red, moist, itchy patches that develop particularly in skin folds. Nail involvement is associated with onycholysis (separation of the nail plate from the nail bed) and subungual debris.¹ Data on the prevalence of candidiasis of the skin and nails in the United States are scarce. In this study, we evaluated the prevalence, characteristics, and treatment practices of candidiasis of the skin and nails using data from 2 large US health insurance claims databases.

Methods

We used the 2023 Merative MarketScan Commercial, Medicare Supplemental, and Multi-State Medicaid Databases (https://www.merative.com/documents/­merative-marketscan-research-databases) to identify outpatients with the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) code B37.2 for candidiasis of the skin and nails. The Commercial and Medicare Supplemental databases include health insurance claims data submitted by large employers and health plans for more than 19 million patients throughout the United States, and the Multi-State Medicaid database includes similar data from more than 5 million patients across several geographically dispersed states. The index date for each patient corresponded with their first qualifying diagnosis of skin and nail candidiasis during January 1, 2023, to December 31, 2023. Inclusion in the study required continuous insurance enrollment from 30 days prior to 7 days after the index date, resulting in exclusion of 7% of commercial/Medicare patients and 8% of Medicaid patients. Prevalence per 1000 out­patients was calculated, with stratification by demographic characteristics.

We examined selected diagnoses made on or within 30 days before the index date, diagnostic testing performed within the 7 days before or after the index date after using specific Current Procedural Terminology codes, and outpatient antifungal and combination ­antifungal-corticosteroid prescriptions made within 7 days before or after the index date (Table). Race/­ethnicity data are unavailable in the commercial/Medicare database, and geographic data are unavailable in the Medicaid database.

Results

The prevalence of skin and nail candidiasis was 3.7 per 1000 commercial/Medicare outpatients and 7.8 per 1000 Medi­caid outpatients (eTable 1). Prevalence was highest among patients aged 0 to 3 years (commercial/Medicare, 30.3 per 1000; Medicaid, 43.6 per 1000), followed by patients 65 years or older (commercial/Medicare, 7.4 per 1000; Medicaid, 7.5 per 1000). Prevalence was higher among females compared with males (commercial/Medicare, 4.8 vs 2.4 per 1000, respectively; Medicaid, 8.8 vs 6.4 per 1000, respectively). Among Medicaid patients, prevalence was highest among those of other race, non-Hispanic (8.9 per 1000) and White non-­Hispanic patients (7.5 per 1000). In the commercial/Medicare dataset, prevalence was highest in patients residing in the Midwest (4.4 per 1000) and the South (4.0 per 1000).

Diaper dermatitis was listed as a concurrent diagnosis among 51% of patients aged 0 to 3 years in both datasets (eTable 2). Diabetes (commercial/Medicare, 32%; Medicaid, 36%) and immunosuppressive conditions (commercial/Medicare, 10%; Medicaid, 7%) were most frequent among patients aged 65 years or older. Obesity was most commonly listed as a concurrent diagnosis among patients aged 35 to 64 years (commercial/Medicare, 17%; Medicaid, 23%).

Patients aged 18 to 34 years had the highest rates of diagnostic testing in the 7 days before or after the index date (commercial/Medicare, 9%; Medicaid, 10%). Topical antifungal medications (primarily nystatin) were most frequently prescribed for patients aged 0 to 3 years ­(commercial/Medicare, 67%; Medicaid, 70%). Topical combination antifungal-corticosteroid medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (16%) and for patients aged 18 to 34 years in the Medicaid dataset (8%). Topical onychomycosis treatments were prescribed for fewer than 1% of patients in both datasets. Oral antifungal medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (26%) and for patients aged 18 to 34 years in the Medicaid dataset (24%). Fewer than 11% of patients across all age groups in both datasets were prescribed both topical and oral antifungal medications.

Comment

Our analysis provides preliminary insight into the prevalence of skin and nail candidiasis in the United States based on health insurance claims data. Higher prevalence of skin and nail candidiasis among patients with Medicaid compared with those with commercial/Medicare health insurance is consistent with previous studies showing increased rates of other superficial fungal infections (eg, dermatophytosis) among patients of lower socioeconomic status.² This finding could reflect differences in underlying health status or reduced access to health care, which could delay treatment or follow-up care and potentially lead to prolonged exposure to conditions favoring the development of candidiasis.

In both the commercial/Medicare health insurance and Medicaid datasets, prevalence of diagnosis codes for candidiasis of the skin and nails was highest among infants and toddlers. Diaper dermatitis also was observed in more than half of patients aged 0 to 3 years; this is a well-established risk factor for cutaneous candidiasis, as immature skin barrier function and prolonged exposure to moisture and occlusion facilitate fungal overgrowth.³ In adults, diabetes and obesity were among the most frequent comorbidities observed; both conditions are recognized risk factors for superficial candidiasis due to their impact on immune function and skin integrity.⁴

In both study cohorts, diagnostic testing in the 7 days before or after the index date was infrequent (≤10%), consistent with most cases being diagnosed clinically.⁵ Topical antifungals, especially nystatin, were most frequently prescribed for young children, while oral antifungals were more frequently prescribed for adults; nystatin is one of the most well-studied topical treatments for cutaneous candidiasis, and oral fluconazole is the primary systemic treatment for cutaneous candidiasis.¹ In our study, the ICD-10-CM code B37.2 appeared to be used primarily for diagnosis of skin rather than nail infections based on the low proportions of patients who received treatment that was onychomycosis specific.

Our study was limited by potential misclassification inherent to data based on diagnosis codes; incomplete capture of underlying conditions given the short continuous enrollment criteria; and lack of information about affected body site(s) and laboratory results, including data identifying the Candida species. A previous study found that Candida parapsilosis and Candida albicans were the most common species involved in candidiasis of the skin and nails and that one-third of isolates exhibited low sensitivity to commonly used antifungals.⁶ For nails, Candida species are sometimes contaminants rather than pathogens.

Conclusion

Our findings provide a baseline understanding of the epidemiology of candidiasis of the skin and nails in the United States. The growing threat of antifungal resistance, particularly among non-albicans Candida species, underscores the need for appropriate use of antifungals.⁷ Future epidemiologic studies about laboratory-confirmed candidiasis of the skin and nails to understand causative species and drug resistance would be useful, as would further investigation into disparities.

Candida is a common commensal organism of human skin and mucous membranes. Candidiasis of the skin and nails is caused by overgrowth of Candida species due to excess skin moisture, skin barrier disruption, or immunosuppression. Candidiasis of the skin manifests as red, moist, itchy patches that develop particularly in skin folds. Nail involvement is associated with onycholysis (separation of the nail plate from the nail bed) and subungual debris.¹ Data on the prevalence of candidiasis of the skin and nails in the United States are scarce. In this study, we evaluated the prevalence, characteristics, and treatment practices of candidiasis of the skin and nails using data from 2 large US health insurance claims databases.

Methods

We used the 2023 Merative MarketScan Commercial, Medicare Supplemental, and Multi-State Medicaid Databases (https://www.merative.com/documents/­merative-marketscan-research-databases) to identify outpatients with the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) code B37.2 for candidiasis of the skin and nails. The Commercial and Medicare Supplemental databases include health insurance claims data submitted by large employers and health plans for more than 19 million patients throughout the United States, and the Multi-State Medicaid database includes similar data from more than 5 million patients across several geographically dispersed states. The index date for each patient corresponded with their first qualifying diagnosis of skin and nail candidiasis during January 1, 2023, to December 31, 2023. Inclusion in the study required continuous insurance enrollment from 30 days prior to 7 days after the index date, resulting in exclusion of 7% of commercial/Medicare patients and 8% of Medicaid patients. Prevalence per 1000 out­patients was calculated, with stratification by demographic characteristics.

We examined selected diagnoses made on or within 30 days before the index date, diagnostic testing performed within the 7 days before or after the index date after using specific Current Procedural Terminology codes, and outpatient antifungal and combination ­antifungal-corticosteroid prescriptions made within 7 days before or after the index date (Table). Race/­ethnicity data are unavailable in the commercial/Medicare database, and geographic data are unavailable in the Medicaid database.

Results

The prevalence of skin and nail candidiasis was 3.7 per 1000 commercial/Medicare outpatients and 7.8 per 1000 Medi­caid outpatients (eTable 1). Prevalence was highest among patients aged 0 to 3 years (commercial/Medicare, 30.3 per 1000; Medicaid, 43.6 per 1000), followed by patients 65 years or older (commercial/Medicare, 7.4 per 1000; Medicaid, 7.5 per 1000). Prevalence was higher among females compared with males (commercial/Medicare, 4.8 vs 2.4 per 1000, respectively; Medicaid, 8.8 vs 6.4 per 1000, respectively). Among Medicaid patients, prevalence was highest among those of other race, non-Hispanic (8.9 per 1000) and White non-­Hispanic patients (7.5 per 1000). In the commercial/Medicare dataset, prevalence was highest in patients residing in the Midwest (4.4 per 1000) and the South (4.0 per 1000).

Diaper dermatitis was listed as a concurrent diagnosis among 51% of patients aged 0 to 3 years in both datasets (eTable 2). Diabetes (commercial/Medicare, 32%; Medicaid, 36%) and immunosuppressive conditions (commercial/Medicare, 10%; Medicaid, 7%) were most frequent among patients aged 65 years or older. Obesity was most commonly listed as a concurrent diagnosis among patients aged 35 to 64 years (commercial/Medicare, 17%; Medicaid, 23%).

Patients aged 18 to 34 years had the highest rates of diagnostic testing in the 7 days before or after the index date (commercial/Medicare, 9%; Medicaid, 10%). Topical antifungal medications (primarily nystatin) were most frequently prescribed for patients aged 0 to 3 years ­(commercial/Medicare, 67%; Medicaid, 70%). Topical combination antifungal-corticosteroid medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (16%) and for patients aged 18 to 34 years in the Medicaid dataset (8%). Topical onychomycosis treatments were prescribed for fewer than 1% of patients in both datasets. Oral antifungal medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (26%) and for patients aged 18 to 34 years in the Medicaid dataset (24%). Fewer than 11% of patients across all age groups in both datasets were prescribed both topical and oral antifungal medications.

Comment

Our analysis provides preliminary insight into the prevalence of skin and nail candidiasis in the United States based on health insurance claims data. Higher prevalence of skin and nail candidiasis among patients with Medicaid compared with those with commercial/Medicare health insurance is consistent with previous studies showing increased rates of other superficial fungal infections (eg, dermatophytosis) among patients of lower socioeconomic status.² This finding could reflect differences in underlying health status or reduced access to health care, which could delay treatment or follow-up care and potentially lead to prolonged exposure to conditions favoring the development of candidiasis.

In both the commercial/Medicare health insurance and Medicaid datasets, prevalence of diagnosis codes for candidiasis of the skin and nails was highest among infants and toddlers. Diaper dermatitis also was observed in more than half of patients aged 0 to 3 years; this is a well-established risk factor for cutaneous candidiasis, as immature skin barrier function and prolonged exposure to moisture and occlusion facilitate fungal overgrowth.³ In adults, diabetes and obesity were among the most frequent comorbidities observed; both conditions are recognized risk factors for superficial candidiasis due to their impact on immune function and skin integrity.⁴

In both study cohorts, diagnostic testing in the 7 days before or after the index date was infrequent (≤10%), consistent with most cases being diagnosed clinically.⁵ Topical antifungals, especially nystatin, were most frequently prescribed for young children, while oral antifungals were more frequently prescribed for adults; nystatin is one of the most well-studied topical treatments for cutaneous candidiasis, and oral fluconazole is the primary systemic treatment for cutaneous candidiasis.¹ In our study, the ICD-10-CM code B37.2 appeared to be used primarily for diagnosis of skin rather than nail infections based on the low proportions of patients who received treatment that was onychomycosis specific.

Our study was limited by potential misclassification inherent to data based on diagnosis codes; incomplete capture of underlying conditions given the short continuous enrollment criteria; and lack of information about affected body site(s) and laboratory results, including data identifying the Candida species. A previous study found that Candida parapsilosis and Candida albicans were the most common species involved in candidiasis of the skin and nails and that one-third of isolates exhibited low sensitivity to commonly used antifungals.⁶ For nails, Candida species are sometimes contaminants rather than pathogens.

Conclusion

Our findings provide a baseline understanding of the epidemiology of candidiasis of the skin and nails in the United States. The growing threat of antifungal resistance, particularly among non-albicans Candida species, underscores the need for appropriate use of antifungals.⁷ Future epidemiologic studies about laboratory-confirmed candidiasis of the skin and nails to understand causative species and drug resistance would be useful, as would further investigation into disparities.

Candida is a common commensal organism of human skin and mucous membranes. Candidiasis of the skin and nails is caused by overgrowth of Candida species due to excess skin moisture, skin barrier disruption, or immunosuppression. Candidiasis of the skin manifests as red, moist, itchy patches that develop particularly in skin folds. Nail involvement is associated with onycholysis (separation of the nail plate from the nail bed) and subungual debris.¹ Data on the prevalence of candidiasis of the skin and nails in the United States are scarce. In this study, we evaluated the prevalence, characteristics, and treatment practices of candidiasis of the skin and nails using data from 2 large US health insurance claims databases.

Methods

We used the 2023 Merative MarketScan Commercial, Medicare Supplemental, and Multi-State Medicaid Databases (https://www.merative.com/documents/­merative-marketscan-research-databases) to identify outpatients with the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) code B37.2 for candidiasis of the skin and nails. The Commercial and Medicare Supplemental databases include health insurance claims data submitted by large employers and health plans for more than 19 million patients throughout the United States, and the Multi-State Medicaid database includes similar data from more than 5 million patients across several geographically dispersed states. The index date for each patient corresponded with their first qualifying diagnosis of skin and nail candidiasis during January 1, 2023, to December 31, 2023. Inclusion in the study required continuous insurance enrollment from 30 days prior to 7 days after the index date, resulting in exclusion of 7% of commercial/Medicare patients and 8% of Medicaid patients. Prevalence per 1000 out­patients was calculated, with stratification by demographic characteristics.

We examined selected diagnoses made on or within 30 days before the index date, diagnostic testing performed within the 7 days before or after the index date after using specific Current Procedural Terminology codes, and outpatient antifungal and combination ­antifungal-corticosteroid prescriptions made within 7 days before or after the index date (Table). Race/­ethnicity data are unavailable in the commercial/Medicare database, and geographic data are unavailable in the Medicaid database.

Results

The prevalence of skin and nail candidiasis was 3.7 per 1000 commercial/Medicare outpatients and 7.8 per 1000 Medi­caid outpatients (eTable 1). Prevalence was highest among patients aged 0 to 3 years (commercial/Medicare, 30.3 per 1000; Medicaid, 43.6 per 1000), followed by patients 65 years or older (commercial/Medicare, 7.4 per 1000; Medicaid, 7.5 per 1000). Prevalence was higher among females compared with males (commercial/Medicare, 4.8 vs 2.4 per 1000, respectively; Medicaid, 8.8 vs 6.4 per 1000, respectively). Among Medicaid patients, prevalence was highest among those of other race, non-Hispanic (8.9 per 1000) and White non-­Hispanic patients (7.5 per 1000). In the commercial/Medicare dataset, prevalence was highest in patients residing in the Midwest (4.4 per 1000) and the South (4.0 per 1000).

Diaper dermatitis was listed as a concurrent diagnosis among 51% of patients aged 0 to 3 years in both datasets (eTable 2). Diabetes (commercial/Medicare, 32%; Medicaid, 36%) and immunosuppressive conditions (commercial/Medicare, 10%; Medicaid, 7%) were most frequent among patients aged 65 years or older. Obesity was most commonly listed as a concurrent diagnosis among patients aged 35 to 64 years (commercial/Medicare, 17%; Medicaid, 23%).

Patients aged 18 to 34 years had the highest rates of diagnostic testing in the 7 days before or after the index date (commercial/Medicare, 9%; Medicaid, 10%). Topical antifungal medications (primarily nystatin) were most frequently prescribed for patients aged 0 to 3 years ­(commercial/Medicare, 67%; Medicaid, 70%). Topical combination antifungal-corticosteroid medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (16%) and for patients aged 18 to 34 years in the Medicaid dataset (8%). Topical onychomycosis treatments were prescribed for fewer than 1% of patients in both datasets. Oral antifungal medications were most frequently prescribed for patients aged 35 to 64 years in the commercial/Medicare dataset (26%) and for patients aged 18 to 34 years in the Medicaid dataset (24%). Fewer than 11% of patients across all age groups in both datasets were prescribed both topical and oral antifungal medications.

Comment

Our analysis provides preliminary insight into the prevalence of skin and nail candidiasis in the United States based on health insurance claims data. Higher prevalence of skin and nail candidiasis among patients with Medicaid compared with those with commercial/Medicare health insurance is consistent with previous studies showing increased rates of other superficial fungal infections (eg, dermatophytosis) among patients of lower socioeconomic status.² This finding could reflect differences in underlying health status or reduced access to health care, which could delay treatment or follow-up care and potentially lead to prolonged exposure to conditions favoring the development of candidiasis.

In both the commercial/Medicare health insurance and Medicaid datasets, prevalence of diagnosis codes for candidiasis of the skin and nails was highest among infants and toddlers. Diaper dermatitis also was observed in more than half of patients aged 0 to 3 years; this is a well-established risk factor for cutaneous candidiasis, as immature skin barrier function and prolonged exposure to moisture and occlusion facilitate fungal overgrowth.³ In adults, diabetes and obesity were among the most frequent comorbidities observed; both conditions are recognized risk factors for superficial candidiasis due to their impact on immune function and skin integrity.⁴

In both study cohorts, diagnostic testing in the 7 days before or after the index date was infrequent (≤10%), consistent with most cases being diagnosed clinically.⁵ Topical antifungals, especially nystatin, were most frequently prescribed for young children, while oral antifungals were more frequently prescribed for adults; nystatin is one of the most well-studied topical treatments for cutaneous candidiasis, and oral fluconazole is the primary systemic treatment for cutaneous candidiasis.¹ In our study, the ICD-10-CM code B37.2 appeared to be used primarily for diagnosis of skin rather than nail infections based on the low proportions of patients who received treatment that was onychomycosis specific.

Our study was limited by potential misclassification inherent to data based on diagnosis codes; incomplete capture of underlying conditions given the short continuous enrollment criteria; and lack of information about affected body site(s) and laboratory results, including data identifying the Candida species. A previous study found that Candida parapsilosis and Candida albicans were the most common species involved in candidiasis of the skin and nails and that one-third of isolates exhibited low sensitivity to commonly used antifungals.⁶ For nails, Candida species are sometimes contaminants rather than pathogens.

Conclusion

Our findings provide a baseline understanding of the epidemiology of candidiasis of the skin and nails in the United States. The growing threat of antifungal resistance, particularly among non-albicans Candida species, underscores the need for appropriate use of antifungals.⁷ Future epidemiologic studies about laboratory-confirmed candidiasis of the skin and nails to understand causative species and drug resistance would be useful, as would further investigation into disparities.

To the Editor:

In dermatology, rupioid describes ­dirty-appearing scale. The term is derived from the Greek word rhupos, which translates to “dirty” or “filthy.” This type of scale also is called ostraceous, owing to its resemblance to an oyster shell. Histopathologically, rupioid or ostraceous scale corresponds to epidermal hyperplasia and hyperkeratosis. Therefore, the presence of rupioid scale is believed to reflect an exuberant inflammatory response. Several dermatologic conditions have been associated with rupioid scale, including psoriasis, secondary syphilis, reactive arthritis, histoplasmosis, and Norwegian scabies.^1-4 Peripheral eosinophilia has been reported in eczematous dermatoses such as atopic dermatitis and contact dermatitis,^5,6 but our review of the literature did not find it described in the context of id reactions. We report the case of a patient who developed a rupioid id reaction with peripheral eosinophilia.

An otherwise healthy 40-year-old woman presented with a generalized pruritic eruption of 1 month’s duration. Prior to onset, she was bitten by a bug on the left arm and covered the site with a bandage. She subsequently noticed an erythematous papulopustular rash corresponding to the shape of the bandage adhesive. Shortly thereafter, a generalized eruption developed, prompting the patient to present for evaluation 1 month later. A review of systems was negative for fevers, chills, headaches, vision changes, and joint symptoms. She denied having a history of atopy.

Physical examination revealed numerous pink papules and plaques with rupioid scale scattered over the trunk and extremities (Figure). The palms, soles, and mucous membranes were spared. Laboratory studies revealed peripheral eosinophilia (9% eosinophils [reference range, 1%-6%] and an absolute eosinophil count of 600/µL [reference range, 0-400/µL]). A 3-mm punch biopsy of a representative lesion revealed a superficial perivascular infiltrate of lymphocytes, histiocytes, and eosinophils along with epidermal hyperplasia, spongiosis, and mounds of parakeratosis. Clinicopathologic correlation led to the diagnosis of a rupioid id reaction secondary to an arthropod assault and/or a reaction to the bandage adhesive.

Treatment with topical corticosteroids was avoided at the patient’s request. Instead, a ceramide-based emollient and oral antihistamines (fexofenadine 180 mg in the morning and cetirizine 10 mg in the evening) were recommended and resulted in resolution of the eruption with postinflammatory hyperpigmentation at 2-week follow-up. The patient was advised to avoid further exposure to bandage adhesives.

An id reaction, or autoeczematization, is a cutaneous immunologic response to antigen(s) released from an initial, often distant site of inflammation.^7,8 Clinically, it typically manifests as a pruritic, symmetrically distributed papulovesicular eruption. Although the pathogenesis of id reactions is uncertain, overactivation of T lymphocytes responding to the initial inflammatory insult has been implicated.⁷ A variety of noninfectious (eg, stasis dermatitis, contact dermatitis) and infectious dermatoses (eg, fungal, bacterial, viral, parasitic) may trigger id reactions.^7,9-13 In this case, we believe an arthropod assault and/or reaction to the bandage adhesive was the primary insult, and the id reaction that ensued was so exuberant that it resulted not only in rupioid scale but also in peripheral eosinophilia—similar to how more severe forms of atopic dermatitis have been associated with peripheral eosinophilia.⁵ As such presentations of id reactions not have been widely described in the literature, this report expands our understanding of this condition to include rupioid scale and peripheral eosinophilia.

To the Editor:

In dermatology, rupioid describes ­dirty-appearing scale. The term is derived from the Greek word rhupos, which translates to “dirty” or “filthy.” This type of scale also is called ostraceous, owing to its resemblance to an oyster shell. Histopathologically, rupioid or ostraceous scale corresponds to epidermal hyperplasia and hyperkeratosis. Therefore, the presence of rupioid scale is believed to reflect an exuberant inflammatory response. Several dermatologic conditions have been associated with rupioid scale, including psoriasis, secondary syphilis, reactive arthritis, histoplasmosis, and Norwegian scabies.^1-4 Peripheral eosinophilia has been reported in eczematous dermatoses such as atopic dermatitis and contact dermatitis,^5,6 but our review of the literature did not find it described in the context of id reactions. We report the case of a patient who developed a rupioid id reaction with peripheral eosinophilia.

An otherwise healthy 40-year-old woman presented with a generalized pruritic eruption of 1 month’s duration. Prior to onset, she was bitten by a bug on the left arm and covered the site with a bandage. She subsequently noticed an erythematous papulopustular rash corresponding to the shape of the bandage adhesive. Shortly thereafter, a generalized eruption developed, prompting the patient to present for evaluation 1 month later. A review of systems was negative for fevers, chills, headaches, vision changes, and joint symptoms. She denied having a history of atopy.

Physical examination revealed numerous pink papules and plaques with rupioid scale scattered over the trunk and extremities (Figure). The palms, soles, and mucous membranes were spared. Laboratory studies revealed peripheral eosinophilia (9% eosinophils [reference range, 1%-6%] and an absolute eosinophil count of 600/µL [reference range, 0-400/µL]). A 3-mm punch biopsy of a representative lesion revealed a superficial perivascular infiltrate of lymphocytes, histiocytes, and eosinophils along with epidermal hyperplasia, spongiosis, and mounds of parakeratosis. Clinicopathologic correlation led to the diagnosis of a rupioid id reaction secondary to an arthropod assault and/or a reaction to the bandage adhesive.

Treatment with topical corticosteroids was avoided at the patient’s request. Instead, a ceramide-based emollient and oral antihistamines (fexofenadine 180 mg in the morning and cetirizine 10 mg in the evening) were recommended and resulted in resolution of the eruption with postinflammatory hyperpigmentation at 2-week follow-up. The patient was advised to avoid further exposure to bandage adhesives.

An id reaction, or autoeczematization, is a cutaneous immunologic response to antigen(s) released from an initial, often distant site of inflammation.^7,8 Clinically, it typically manifests as a pruritic, symmetrically distributed papulovesicular eruption. Although the pathogenesis of id reactions is uncertain, overactivation of T lymphocytes responding to the initial inflammatory insult has been implicated.⁷ A variety of noninfectious (eg, stasis dermatitis, contact dermatitis) and infectious dermatoses (eg, fungal, bacterial, viral, parasitic) may trigger id reactions.^7,9-13 In this case, we believe an arthropod assault and/or reaction to the bandage adhesive was the primary insult, and the id reaction that ensued was so exuberant that it resulted not only in rupioid scale but also in peripheral eosinophilia—similar to how more severe forms of atopic dermatitis have been associated with peripheral eosinophilia.⁵ As such presentations of id reactions not have been widely described in the literature, this report expands our understanding of this condition to include rupioid scale and peripheral eosinophilia.

To the Editor:

In dermatology, rupioid describes ­dirty-appearing scale. The term is derived from the Greek word rhupos, which translates to “dirty” or “filthy.” This type of scale also is called ostraceous, owing to its resemblance to an oyster shell. Histopathologically, rupioid or ostraceous scale corresponds to epidermal hyperplasia and hyperkeratosis. Therefore, the presence of rupioid scale is believed to reflect an exuberant inflammatory response. Several dermatologic conditions have been associated with rupioid scale, including psoriasis, secondary syphilis, reactive arthritis, histoplasmosis, and Norwegian scabies.^1-4 Peripheral eosinophilia has been reported in eczematous dermatoses such as atopic dermatitis and contact dermatitis,^5,6 but our review of the literature did not find it described in the context of id reactions. We report the case of a patient who developed a rupioid id reaction with peripheral eosinophilia.

An otherwise healthy 40-year-old woman presented with a generalized pruritic eruption of 1 month’s duration. Prior to onset, she was bitten by a bug on the left arm and covered the site with a bandage. She subsequently noticed an erythematous papulopustular rash corresponding to the shape of the bandage adhesive. Shortly thereafter, a generalized eruption developed, prompting the patient to present for evaluation 1 month later. A review of systems was negative for fevers, chills, headaches, vision changes, and joint symptoms. She denied having a history of atopy.

Physical examination revealed numerous pink papules and plaques with rupioid scale scattered over the trunk and extremities (Figure). The palms, soles, and mucous membranes were spared. Laboratory studies revealed peripheral eosinophilia (9% eosinophils [reference range, 1%-6%] and an absolute eosinophil count of 600/µL [reference range, 0-400/µL]). A 3-mm punch biopsy of a representative lesion revealed a superficial perivascular infiltrate of lymphocytes, histiocytes, and eosinophils along with epidermal hyperplasia, spongiosis, and mounds of parakeratosis. Clinicopathologic correlation led to the diagnosis of a rupioid id reaction secondary to an arthropod assault and/or a reaction to the bandage adhesive.

Treatment with topical corticosteroids was avoided at the patient’s request. Instead, a ceramide-based emollient and oral antihistamines (fexofenadine 180 mg in the morning and cetirizine 10 mg in the evening) were recommended and resulted in resolution of the eruption with postinflammatory hyperpigmentation at 2-week follow-up. The patient was advised to avoid further exposure to bandage adhesives.

An id reaction, or autoeczematization, is a cutaneous immunologic response to antigen(s) released from an initial, often distant site of inflammation.^7,8 Clinically, it typically manifests as a pruritic, symmetrically distributed papulovesicular eruption. Although the pathogenesis of id reactions is uncertain, overactivation of T lymphocytes responding to the initial inflammatory insult has been implicated.⁷ A variety of noninfectious (eg, stasis dermatitis, contact dermatitis) and infectious dermatoses (eg, fungal, bacterial, viral, parasitic) may trigger id reactions.^7,9-13 In this case, we believe an arthropod assault and/or reaction to the bandage adhesive was the primary insult, and the id reaction that ensued was so exuberant that it resulted not only in rupioid scale but also in peripheral eosinophilia—similar to how more severe forms of atopic dermatitis have been associated with peripheral eosinophilia.⁵ As such presentations of id reactions not have been widely described in the literature, this report expands our understanding of this condition to include rupioid scale and peripheral eosinophilia.

Sporotrichosis is an implantation mycosis that classically manifests as a localized skin and subcutaneous fungal infection but may disseminate to other parts of the body.¹ It is caused by several species within the Sporothrix genus² and is associated with varying clinical manifestations, geographic distributions, virulence profiles, and antifungal susceptibility patterns.^3,4 Transmission of the fungus can involve inoculation from wild or domestic animals (eg, cats).^5,6 Occupations such as landscaping and gardening or elements in the environment (eg, soil, plant fragments) also can be sources of exposure.^7,8

Sporotrichosis is recognized by the World Health Organization as a neglected tropical disease that warrants global advocacy to prevent infections and improve patient outcomes.^9,10 It carries substantial stigma and socioeconomic burden.^11,12 Diagnostics, species identification, and antifungal susceptibility testing often are limited, particularly in resource-limited settings.¹³ In this article, we outline steps to diagnose and manage sporotrichosis to improve care for affected patients globally.

Epidemiology

Sporotrichosis occurs worldwide but is most common in tropical and subtropical regions.^14,15 Outbreaks and clusters of sporotrichosis have been observed across North, Central, and South America as well as in southern Africa and Asia. The estimated annual incidence is 40,000 cases worldwide,^16-20 but global case counts likely are underestimated due to limited surveillance data and diagnostic capability.²¹

On the Asian subcontinent, Sporothrix globosa is the predominant causative species of sporotrichosis, typically via contaminated plant material²²; however, at least 1 outbreak has been associated with severe flooding.²³ In Africa, infections are most commonly caused by Sporothrix schenckii sensu stricto through a similar transmission route. Across Central America, S schenckii sensu stricto is the predominant causative species; however, Sporothrix brasiliensis is the predominant species in some countries in South America, particularly Brazil.²⁰   

Data describing the current geographic distribution and prevalence of sporotrichosis in the United States are limited. Historically, the disease was reported most commonly in Midwestern states and was associated with outbreaks related to handling Sphagnum moss.^24,25 Epidemiologic studies using health insurance data indicate an average annual incidence of 2.0 cases per million individuals in the United States, with a higher prevalence among women and a median age at diagnosis of 54 years.²⁶ A review of sporotrichosis-associated hospitalizations across the United States from 2000 to 2013 indicated an average hospitalization rate of 0.35 cases per 1 million individuals; rates were higher (0.45 cases per million) in the West and lower (0.15 per million) in the Northeast and in men (0.40 per million).²⁷ Type 2 diabetes, immune-mediated inflammatory disease, and chronic obstructive pulmonary disease are associated with an increased risk for infection and hospitalization.²⁷

Causative Organisms

Sporothrix species are thermally dimorphic fungi that can grow as mold in the environment and as yeast in human tissue. Sporothrix brasiliensis is the only thermodimorphic fungus known to be transmitted directly in its yeast form.²⁸ In other species, inoculation usually occurs after contact with contaminated soil or plant material during gardening, carpentry, or agricultural practices.⁷

Zoonotic transmission of sporotrichosis from animals to humans has been reported from a range of domestic and wild animals and birds but historically has been rare.^5,7,29,30 Recently, the importance of both cat-to-cat (epizootic) and cat-to-human (zoonotic) transmission of S brasiliensis has been recognized, with infection typically following traumatic inoculation after a scratch or bite; less frequently, transmission occurs due to exposure to respiratory droplets or contact with feline exudates.^5,29,31 Sporothrix brasiliensis is responsible for zoonotic epidemics in South America, primarily in Brazil. Transmission occurs among humans, cats, and canines, with felines serving as the primary vector.³² Transmission of this species is particularly common in stray and unneutered male cats that exhibit aggressive behaviors.³³ This species also is thought to be the most virulent Sporothrix species.²¹

Sporothrix brasiliensis can persist on nondisinfected inanimate surfaces, which suggests that fomite transmission can lead to human infection.³¹ The epidemiology of sporotrichosis has transformed in regions where S brasiliensis circulates, with epidemic spread resulting in thousands of cases, whereas in other areas without S brasilinesis, sporotrichosis predominantly occurs sporadically with rare clusters.^1,2,7,15

Sporotrichosis has been the subject of a taxonomic debate in the mycology community.²¹ Sporothrix schenckii sensu lato originally was believed to be the sole fungal pathogen causing sporotrichosis³⁴ but was later divided into S schenckii sensu stricto, Sporothrix globosa, and S brasiliensis.³⁵ More than 60 distinct species now have been described within the Sporothrix genus,^36,37 but the primary species causing human sporotrichosis include S schenckii sensu stricto, S brasiliensis, S globosa, Sporothrix mexicana, and Sporothrix luriei.³⁵ Both S schenckii and S brasiliensis have greater virulence than other Sporothrix species⁴; however, S schenckii causes infections that typically are localized and are milder, while S brasiliensis can lead to more atypical, severe, and disseminated infections^38,39 and can spread epidemically.

Clinical Manifestations

Sporotrichosis has 4 main clinical presentations: cutaneous lymphatic, fixed cutaneous, cutaneous or systemic disseminated, and extracutaneous.^40,41 The most common clinical manifestation is the cutaneous lymphatic form, which predominantly affects the hands and forearms in adults and the face in children.⁷ The primary lesion usually manifests as a unilateral papule, nodule, or pustule that may ulcerate (sporotrichotic chancre), but multiple sites of inoculation are possible. Subsequent lesions may appear in a linear distribution along a regional lymphatic path (sporotrichoid spread). Systemic symptoms and regional lymphadenopathy are uncommon and usually are mild.

The second most common clinical manifestation is the fixed cutaneous form, typically affecting the face, neck, trunk, or legs with a single papule, nodule, or verrucous lesion with no lymphangitic spread.⁷ Usually confined to the inoculation site, the primary lesion may be accompanied by satellite lesions and often presents a diagnostic challenge.

Disseminated sporotrichosis (either cutaneous or systemic) is rare. Disseminated cutaneous sporotrichosis manifests with multiple noncontiguous skin lesions caused by lymphatic and possible hematogenous spread. Lesions may include a combination of papules, pustules, follicular eruptions, crusted plaques, and ulcers that may mimic other systemic infections. Immunoreactive changes such as erythema nodosum, erythema multiforme, or arthritis may accompany skin lesions, most commonly with S brasiliensis infections. Nearly 10% of S brasiliensis infections involve the ocular adnexa, and Parinaud oculoglandular syndrome is commonly described in cases reported in Brazil.^42,43 Disseminated disease usually occurs in immunocompromised hosts; however, despite a focus on HIV co-infection,^8,44 prior epidemiologic research has suggested that diabetes and alcoholism are the most common predisposing factors.⁴⁵ Systemic disseminated sporotrichosis by definition affects at least 2 body systems, most commonly the central nervous system, lungs, and musculoskeletal system (including joints and bone marrow).⁴⁵

Extracutaneous sporotrichosis is rare and often is difficult to diagnose. Risk factors include chronic obstructive pulmonary disease, alcoholism, use of steroid medications, AIDS, solid organ transplantation, and use of tumor necrosis factor α inhibitors. It usually affects bony structures through hematogenous spread in immunocompromised hosts and is associated with a high risk for osteomyelitis due to delayed diagnosis.²

Clinical progression of sporotrichosis usually is slow, and lesions may persist for months or years if untreated. Sporotrichosis should always be considered for atypical, persistent, or treatment-resistant manifestations of nodular or ulcerated skin lesions in endemic regions or acute illness with these symptoms following exposure. Preventing secondary bacterial infection is an important consideration as it can exacerbate disease severity, extend the treatment duration, prolong hospitalization, and increase mortality risk.⁴⁶

Diagnosis

In regions endemic for S brasiliensis, it may be acceptable to commence treatment on clinical suspicion without a definitive diagnosis,²¹ but caution is necessary, as lesions easily can be mistaken for other conditions such as Mycobacterium marinum infections (sporotrichoid lesions) or cutaneous leishmaniasis. Limited availability of molecular diagnostic tools in routine clinical laboratories affects the diagnosis of sporotrichosis and species identification. Direct microscopy on a 10% to 30% potassium hydroxide wet mount has low diagnostic sensitivity and is not recommended⁴⁷; findings typically include cigar-shaped yeast cells (eFigure 1). Biopsy and histopathology also are useful, although in many infections (other than those due to S brasiliensis) there are very few detectable organisms in the tissue. Fluorescent staining of fungi with optical brighteners (eg, Calcofluor, Blankophor) is a useful technique with high sensitivity in clinical specimens on histopathologic and direct examination.⁴⁸

Fungal culture has higher sensitivity and specificity than microscopy and is the gold-standard approach for diagnosis of sporotrichosis (eFigure 2); however, culture cannot differentiate between Sporothrix species and may take more than a month to yield a positive result.⁷ No reliable serologic test for sporotrichosis has been validated, and a standardized antigen assay currently is unavailable.⁴⁹ Serology may be more useful for patients who present with systemic disease or have persistently negative culture results despite a high index of suspicion. 

A recent study evaluated the effectiveness of a lateral flow assay for detecting anti-Sporothrix antibodies, demonstrating the potential for its use as a rapid diagnostic test.⁵⁰ Investigating different molecular methods to increase the sensitivity and specificity of diagnosis and distinguish Sporothrix species has been a focus of recent research, with a preference for polymerase chain reaction (PCR)–based genotypic methods.^13,51 Recent advances in diagnostic testing include the development of multiplex PCR,⁵² culture-independent PCR techniques,⁵³ and matrix-assisted laser desorption/ionization–time of flight mass spectrometry,⁵⁴ each with varying clinical and practical applicability. Specialized testing can be beneficial for patients who have a poor therapeutic response to standard treatment, guide antifungal treatment choices, and identify epidemiologic disease and transmission patterns.²¹

Although rarely performed, antifungal susceptibility testing may be useful in guiding therapy to improve patient outcomes, particularly in the context of treatment failure, which has been documented with isolates exhibiting high minimal inhibitory concentrations (MICs) to first-line therapy and a poor clinical response.^55,56 Proposed mechanisms of resistance include increased cellular melanin ­production, which protects against oxidative stress and reduces antifungal activity.⁵⁶ Antifungal susceptibility profiles for therapeutics vary across Sporothrix species; for example, S brasiliensis generally shows lower MICs to itraconazole and terbinafine compared with S schenckii and S globosa, and S schenckii has shown a high MIC to itraconazole, as reflected in MIC distribution studies and epidemiologic cutoff values for antifungal agents.^55,57-59 However, specific breakpoints for different Sporothrix species have not been determined.⁶⁰ Robust clinical studies are needed to determine the correlation of in vitro MICs to clinical outcomes to assess the utility of antifungal susceptibility testing for Sporothrix species.

Management

Treatment of sporotrichosis is guided by clinical presentation, host immune status, and species identification. Management can be challenging in cases with an atypical or delayed diagnosis and limited access to molecular testing methods. Itraconazole is the first-line therapy for management of cutaneous sporotrichosis. It is regarded as safe, effective, well tolerated, and easily administered, with doses ranging from 100 mg in mild cases to 400 mg (with daily or twice-daily dosing).⁶¹ Treatment usually is for 3 to 6 months and should continue for 1 month after complete clinical resolution is achieved⁶²; however, some cases of S brasiliensis infection require longer treatment, and complex or disseminated cases may require therapy for up to 12 months.⁶¹ Itraconazole is contraindicated in pregnancy and has many drug interactions (through cytochrome P450 inhibition) that may preclude administration, particularly in elderly populations. Therapeutic drug monitoring is recommended for prolonged or high-dose therapy, with periodic liver function testing to reduce the risk for toxicity. Itraconazole should be administered with food, and concurrent use of antacids or proton pump inhibitors should be avoided.⁶¹

Oral terbinafine (250 mg daily) can be considered as an effective alternative to treat cutaneous disease.⁶³ Particularly in resource-limited settings, potassium iodide is an affordable and effective treatment for cutaneous sporotrichosis, administered as a saturated oral solution,⁶⁴ but due to adverse effects such as severe nausea, the daily dose should be increased slowly each day to ensure tolerance.

Amphotericin B is the treatment of choice for severe and treatment-resistant cases of sporotrichosis as well as for immunocompromised patients.^21,61 In patients with HIV, a longer treatment course is recommended with oversight from an infectious diseases specialist and usually is followed by a 12-month course of itraconazole after completion of initial therapy.⁶¹ Surgical excision infrequently is recommended but can be used in combination with another treatment modality and may be useful with a slow or incomplete response to medical therapy. Thermotherapy involves direct application of heat to cutaneous lesions and may be considered for small and localized lesions, particularly if antifungal agents are contraindicated or poorly tolerated.⁶¹ Public health measures include promoting case detection through practitioner education and patient awareness in endemic regions, as well as zoonotic control of infected animals to manage sporotrichosis.

Final Thoughts

Sporotrichosis is a fungal infection with growing public health significance. While the global disease burden is unknown, rising case numbers and geographic spread likely reflect a complex interaction between humans, the environment, and animals, exemplified by the spread of feline-associated infection due to S brasiliensis in South America.²⁸ Cases of S brasiliensis infection after importation of an affected cat have been detected outside South America, and clinicians should be alert for introduction to the United States. Strengthening genotypic and phenotypic diagnostic capabilities will allow species identification and guide treatment and management. Disease surveillance and operational research will inform public health approaches to control sporotrichosis worldwide.

Sporotrichosis is an implantation mycosis that classically manifests as a localized skin and subcutaneous fungal infection but may disseminate to other parts of the body.¹ It is caused by several species within the Sporothrix genus² and is associated with varying clinical manifestations, geographic distributions, virulence profiles, and antifungal susceptibility patterns.^3,4 Transmission of the fungus can involve inoculation from wild or domestic animals (eg, cats).^5,6 Occupations such as landscaping and gardening or elements in the environment (eg, soil, plant fragments) also can be sources of exposure.^7,8

Sporotrichosis is recognized by the World Health Organization as a neglected tropical disease that warrants global advocacy to prevent infections and improve patient outcomes.^9,10 It carries substantial stigma and socioeconomic burden.^11,12 Diagnostics, species identification, and antifungal susceptibility testing often are limited, particularly in resource-limited settings.¹³ In this article, we outline steps to diagnose and manage sporotrichosis to improve care for affected patients globally.

Epidemiology

Sporotrichosis occurs worldwide but is most common in tropical and subtropical regions.^14,15 Outbreaks and clusters of sporotrichosis have been observed across North, Central, and South America as well as in southern Africa and Asia. The estimated annual incidence is 40,000 cases worldwide,^16-20 but global case counts likely are underestimated due to limited surveillance data and diagnostic capability.²¹

On the Asian subcontinent, Sporothrix globosa is the predominant causative species of sporotrichosis, typically via contaminated plant material²²; however, at least 1 outbreak has been associated with severe flooding.²³ In Africa, infections are most commonly caused by Sporothrix schenckii sensu stricto through a similar transmission route. Across Central America, S schenckii sensu stricto is the predominant causative species; however, Sporothrix brasiliensis is the predominant species in some countries in South America, particularly Brazil.²⁰   

Data describing the current geographic distribution and prevalence of sporotrichosis in the United States are limited. Historically, the disease was reported most commonly in Midwestern states and was associated with outbreaks related to handling Sphagnum moss.^24,25 Epidemiologic studies using health insurance data indicate an average annual incidence of 2.0 cases per million individuals in the United States, with a higher prevalence among women and a median age at diagnosis of 54 years.²⁶ A review of sporotrichosis-associated hospitalizations across the United States from 2000 to 2013 indicated an average hospitalization rate of 0.35 cases per 1 million individuals; rates were higher (0.45 cases per million) in the West and lower (0.15 per million) in the Northeast and in men (0.40 per million).²⁷ Type 2 diabetes, immune-mediated inflammatory disease, and chronic obstructive pulmonary disease are associated with an increased risk for infection and hospitalization.²⁷

Causative Organisms

Sporothrix species are thermally dimorphic fungi that can grow as mold in the environment and as yeast in human tissue. Sporothrix brasiliensis is the only thermodimorphic fungus known to be transmitted directly in its yeast form.²⁸ In other species, inoculation usually occurs after contact with contaminated soil or plant material during gardening, carpentry, or agricultural practices.⁷

Zoonotic transmission of sporotrichosis from animals to humans has been reported from a range of domestic and wild animals and birds but historically has been rare.^5,7,29,30 Recently, the importance of both cat-to-cat (epizootic) and cat-to-human (zoonotic) transmission of S brasiliensis has been recognized, with infection typically following traumatic inoculation after a scratch or bite; less frequently, transmission occurs due to exposure to respiratory droplets or contact with feline exudates.^5,29,31 Sporothrix brasiliensis is responsible for zoonotic epidemics in South America, primarily in Brazil. Transmission occurs among humans, cats, and canines, with felines serving as the primary vector.³² Transmission of this species is particularly common in stray and unneutered male cats that exhibit aggressive behaviors.³³ This species also is thought to be the most virulent Sporothrix species.²¹

Sporothrix brasiliensis can persist on nondisinfected inanimate surfaces, which suggests that fomite transmission can lead to human infection.³¹ The epidemiology of sporotrichosis has transformed in regions where S brasiliensis circulates, with epidemic spread resulting in thousands of cases, whereas in other areas without S brasilinesis, sporotrichosis predominantly occurs sporadically with rare clusters.^1,2,7,15

Sporotrichosis has been the subject of a taxonomic debate in the mycology community.²¹ Sporothrix schenckii sensu lato originally was believed to be the sole fungal pathogen causing sporotrichosis³⁴ but was later divided into S schenckii sensu stricto, Sporothrix globosa, and S brasiliensis.³⁵ More than 60 distinct species now have been described within the Sporothrix genus,^36,37 but the primary species causing human sporotrichosis include S schenckii sensu stricto, S brasiliensis, S globosa, Sporothrix mexicana, and Sporothrix luriei.³⁵ Both S schenckii and S brasiliensis have greater virulence than other Sporothrix species⁴; however, S schenckii causes infections that typically are localized and are milder, while S brasiliensis can lead to more atypical, severe, and disseminated infections^38,39 and can spread epidemically.

Clinical Manifestations

Sporotrichosis has 4 main clinical presentations: cutaneous lymphatic, fixed cutaneous, cutaneous or systemic disseminated, and extracutaneous.^40,41 The most common clinical manifestation is the cutaneous lymphatic form, which predominantly affects the hands and forearms in adults and the face in children.⁷ The primary lesion usually manifests as a unilateral papule, nodule, or pustule that may ulcerate (sporotrichotic chancre), but multiple sites of inoculation are possible. Subsequent lesions may appear in a linear distribution along a regional lymphatic path (sporotrichoid spread). Systemic symptoms and regional lymphadenopathy are uncommon and usually are mild.

The second most common clinical manifestation is the fixed cutaneous form, typically affecting the face, neck, trunk, or legs with a single papule, nodule, or verrucous lesion with no lymphangitic spread.⁷ Usually confined to the inoculation site, the primary lesion may be accompanied by satellite lesions and often presents a diagnostic challenge.

Disseminated sporotrichosis (either cutaneous or systemic) is rare. Disseminated cutaneous sporotrichosis manifests with multiple noncontiguous skin lesions caused by lymphatic and possible hematogenous spread. Lesions may include a combination of papules, pustules, follicular eruptions, crusted plaques, and ulcers that may mimic other systemic infections. Immunoreactive changes such as erythema nodosum, erythema multiforme, or arthritis may accompany skin lesions, most commonly with S brasiliensis infections. Nearly 10% of S brasiliensis infections involve the ocular adnexa, and Parinaud oculoglandular syndrome is commonly described in cases reported in Brazil.^42,43 Disseminated disease usually occurs in immunocompromised hosts; however, despite a focus on HIV co-infection,^8,44 prior epidemiologic research has suggested that diabetes and alcoholism are the most common predisposing factors.⁴⁵ Systemic disseminated sporotrichosis by definition affects at least 2 body systems, most commonly the central nervous system, lungs, and musculoskeletal system (including joints and bone marrow).⁴⁵

Extracutaneous sporotrichosis is rare and often is difficult to diagnose. Risk factors include chronic obstructive pulmonary disease, alcoholism, use of steroid medications, AIDS, solid organ transplantation, and use of tumor necrosis factor α inhibitors. It usually affects bony structures through hematogenous spread in immunocompromised hosts and is associated with a high risk for osteomyelitis due to delayed diagnosis.²

Clinical progression of sporotrichosis usually is slow, and lesions may persist for months or years if untreated. Sporotrichosis should always be considered for atypical, persistent, or treatment-resistant manifestations of nodular or ulcerated skin lesions in endemic regions or acute illness with these symptoms following exposure. Preventing secondary bacterial infection is an important consideration as it can exacerbate disease severity, extend the treatment duration, prolong hospitalization, and increase mortality risk.⁴⁶

Diagnosis

In regions endemic for S brasiliensis, it may be acceptable to commence treatment on clinical suspicion without a definitive diagnosis,²¹ but caution is necessary, as lesions easily can be mistaken for other conditions such as Mycobacterium marinum infections (sporotrichoid lesions) or cutaneous leishmaniasis. Limited availability of molecular diagnostic tools in routine clinical laboratories affects the diagnosis of sporotrichosis and species identification. Direct microscopy on a 10% to 30% potassium hydroxide wet mount has low diagnostic sensitivity and is not recommended⁴⁷; findings typically include cigar-shaped yeast cells (eFigure 1). Biopsy and histopathology also are useful, although in many infections (other than those due to S brasiliensis) there are very few detectable organisms in the tissue. Fluorescent staining of fungi with optical brighteners (eg, Calcofluor, Blankophor) is a useful technique with high sensitivity in clinical specimens on histopathologic and direct examination.⁴⁸

Fungal culture has higher sensitivity and specificity than microscopy and is the gold-standard approach for diagnosis of sporotrichosis (eFigure 2); however, culture cannot differentiate between Sporothrix species and may take more than a month to yield a positive result.⁷ No reliable serologic test for sporotrichosis has been validated, and a standardized antigen assay currently is unavailable.⁴⁹ Serology may be more useful for patients who present with systemic disease or have persistently negative culture results despite a high index of suspicion. 

A recent study evaluated the effectiveness of a lateral flow assay for detecting anti-Sporothrix antibodies, demonstrating the potential for its use as a rapid diagnostic test.⁵⁰ Investigating different molecular methods to increase the sensitivity and specificity of diagnosis and distinguish Sporothrix species has been a focus of recent research, with a preference for polymerase chain reaction (PCR)–based genotypic methods.^13,51 Recent advances in diagnostic testing include the development of multiplex PCR,⁵² culture-independent PCR techniques,⁵³ and matrix-assisted laser desorption/ionization–time of flight mass spectrometry,⁵⁴ each with varying clinical and practical applicability. Specialized testing can be beneficial for patients who have a poor therapeutic response to standard treatment, guide antifungal treatment choices, and identify epidemiologic disease and transmission patterns.²¹

Although rarely performed, antifungal susceptibility testing may be useful in guiding therapy to improve patient outcomes, particularly in the context of treatment failure, which has been documented with isolates exhibiting high minimal inhibitory concentrations (MICs) to first-line therapy and a poor clinical response.^55,56 Proposed mechanisms of resistance include increased cellular melanin ­production, which protects against oxidative stress and reduces antifungal activity.⁵⁶ Antifungal susceptibility profiles for therapeutics vary across Sporothrix species; for example, S brasiliensis generally shows lower MICs to itraconazole and terbinafine compared with S schenckii and S globosa, and S schenckii has shown a high MIC to itraconazole, as reflected in MIC distribution studies and epidemiologic cutoff values for antifungal agents.^55,57-59 However, specific breakpoints for different Sporothrix species have not been determined.⁶⁰ Robust clinical studies are needed to determine the correlation of in vitro MICs to clinical outcomes to assess the utility of antifungal susceptibility testing for Sporothrix species.

Management

Treatment of sporotrichosis is guided by clinical presentation, host immune status, and species identification. Management can be challenging in cases with an atypical or delayed diagnosis and limited access to molecular testing methods. Itraconazole is the first-line therapy for management of cutaneous sporotrichosis. It is regarded as safe, effective, well tolerated, and easily administered, with doses ranging from 100 mg in mild cases to 400 mg (with daily or twice-daily dosing).⁶¹ Treatment usually is for 3 to 6 months and should continue for 1 month after complete clinical resolution is achieved⁶²; however, some cases of S brasiliensis infection require longer treatment, and complex or disseminated cases may require therapy for up to 12 months.⁶¹ Itraconazole is contraindicated in pregnancy and has many drug interactions (through cytochrome P450 inhibition) that may preclude administration, particularly in elderly populations. Therapeutic drug monitoring is recommended for prolonged or high-dose therapy, with periodic liver function testing to reduce the risk for toxicity. Itraconazole should be administered with food, and concurrent use of antacids or proton pump inhibitors should be avoided.⁶¹

Oral terbinafine (250 mg daily) can be considered as an effective alternative to treat cutaneous disease.⁶³ Particularly in resource-limited settings, potassium iodide is an affordable and effective treatment for cutaneous sporotrichosis, administered as a saturated oral solution,⁶⁴ but due to adverse effects such as severe nausea, the daily dose should be increased slowly each day to ensure tolerance.

Amphotericin B is the treatment of choice for severe and treatment-resistant cases of sporotrichosis as well as for immunocompromised patients.^21,61 In patients with HIV, a longer treatment course is recommended with oversight from an infectious diseases specialist and usually is followed by a 12-month course of itraconazole after completion of initial therapy.⁶¹ Surgical excision infrequently is recommended but can be used in combination with another treatment modality and may be useful with a slow or incomplete response to medical therapy. Thermotherapy involves direct application of heat to cutaneous lesions and may be considered for small and localized lesions, particularly if antifungal agents are contraindicated or poorly tolerated.⁶¹ Public health measures include promoting case detection through practitioner education and patient awareness in endemic regions, as well as zoonotic control of infected animals to manage sporotrichosis.

Final Thoughts

Sporotrichosis is a fungal infection with growing public health significance. While the global disease burden is unknown, rising case numbers and geographic spread likely reflect a complex interaction between humans, the environment, and animals, exemplified by the spread of feline-associated infection due to S brasiliensis in South America.²⁸ Cases of S brasiliensis infection after importation of an affected cat have been detected outside South America, and clinicians should be alert for introduction to the United States. Strengthening genotypic and phenotypic diagnostic capabilities will allow species identification and guide treatment and management. Disease surveillance and operational research will inform public health approaches to control sporotrichosis worldwide.

Sporotrichosis is an implantation mycosis that classically manifests as a localized skin and subcutaneous fungal infection but may disseminate to other parts of the body.¹ It is caused by several species within the Sporothrix genus² and is associated with varying clinical manifestations, geographic distributions, virulence profiles, and antifungal susceptibility patterns.^3,4 Transmission of the fungus can involve inoculation from wild or domestic animals (eg, cats).^5,6 Occupations such as landscaping and gardening or elements in the environment (eg, soil, plant fragments) also can be sources of exposure.^7,8

Sporotrichosis is recognized by the World Health Organization as a neglected tropical disease that warrants global advocacy to prevent infections and improve patient outcomes.^9,10 It carries substantial stigma and socioeconomic burden.^11,12 Diagnostics, species identification, and antifungal susceptibility testing often are limited, particularly in resource-limited settings.¹³ In this article, we outline steps to diagnose and manage sporotrichosis to improve care for affected patients globally.

Epidemiology

Sporotrichosis occurs worldwide but is most common in tropical and subtropical regions.^14,15 Outbreaks and clusters of sporotrichosis have been observed across North, Central, and South America as well as in southern Africa and Asia. The estimated annual incidence is 40,000 cases worldwide,^16-20 but global case counts likely are underestimated due to limited surveillance data and diagnostic capability.²¹

On the Asian subcontinent, Sporothrix globosa is the predominant causative species of sporotrichosis, typically via contaminated plant material²²; however, at least 1 outbreak has been associated with severe flooding.²³ In Africa, infections are most commonly caused by Sporothrix schenckii sensu stricto through a similar transmission route. Across Central America, S schenckii sensu stricto is the predominant causative species; however, Sporothrix brasiliensis is the predominant species in some countries in South America, particularly Brazil.²⁰   

Data describing the current geographic distribution and prevalence of sporotrichosis in the United States are limited. Historically, the disease was reported most commonly in Midwestern states and was associated with outbreaks related to handling Sphagnum moss.^24,25 Epidemiologic studies using health insurance data indicate an average annual incidence of 2.0 cases per million individuals in the United States, with a higher prevalence among women and a median age at diagnosis of 54 years.²⁶ A review of sporotrichosis-associated hospitalizations across the United States from 2000 to 2013 indicated an average hospitalization rate of 0.35 cases per 1 million individuals; rates were higher (0.45 cases per million) in the West and lower (0.15 per million) in the Northeast and in men (0.40 per million).²⁷ Type 2 diabetes, immune-mediated inflammatory disease, and chronic obstructive pulmonary disease are associated with an increased risk for infection and hospitalization.²⁷

Causative Organisms

Sporothrix species are thermally dimorphic fungi that can grow as mold in the environment and as yeast in human tissue. Sporothrix brasiliensis is the only thermodimorphic fungus known to be transmitted directly in its yeast form.²⁸ In other species, inoculation usually occurs after contact with contaminated soil or plant material during gardening, carpentry, or agricultural practices.⁷

Zoonotic transmission of sporotrichosis from animals to humans has been reported from a range of domestic and wild animals and birds but historically has been rare.^5,7,29,30 Recently, the importance of both cat-to-cat (epizootic) and cat-to-human (zoonotic) transmission of S brasiliensis has been recognized, with infection typically following traumatic inoculation after a scratch or bite; less frequently, transmission occurs due to exposure to respiratory droplets or contact with feline exudates.^5,29,31 Sporothrix brasiliensis is responsible for zoonotic epidemics in South America, primarily in Brazil. Transmission occurs among humans, cats, and canines, with felines serving as the primary vector.³² Transmission of this species is particularly common in stray and unneutered male cats that exhibit aggressive behaviors.³³ This species also is thought to be the most virulent Sporothrix species.²¹

Sporothrix brasiliensis can persist on nondisinfected inanimate surfaces, which suggests that fomite transmission can lead to human infection.³¹ The epidemiology of sporotrichosis has transformed in regions where S brasiliensis circulates, with epidemic spread resulting in thousands of cases, whereas in other areas without S brasilinesis, sporotrichosis predominantly occurs sporadically with rare clusters.^1,2,7,15

Sporotrichosis has been the subject of a taxonomic debate in the mycology community.²¹ Sporothrix schenckii sensu lato originally was believed to be the sole fungal pathogen causing sporotrichosis³⁴ but was later divided into S schenckii sensu stricto, Sporothrix globosa, and S brasiliensis.³⁵ More than 60 distinct species now have been described within the Sporothrix genus,^36,37 but the primary species causing human sporotrichosis include S schenckii sensu stricto, S brasiliensis, S globosa, Sporothrix mexicana, and Sporothrix luriei.³⁵ Both S schenckii and S brasiliensis have greater virulence than other Sporothrix species⁴; however, S schenckii causes infections that typically are localized and are milder, while S brasiliensis can lead to more atypical, severe, and disseminated infections^38,39 and can spread epidemically.

Clinical Manifestations

Sporotrichosis has 4 main clinical presentations: cutaneous lymphatic, fixed cutaneous, cutaneous or systemic disseminated, and extracutaneous.^40,41 The most common clinical manifestation is the cutaneous lymphatic form, which predominantly affects the hands and forearms in adults and the face in children.⁷ The primary lesion usually manifests as a unilateral papule, nodule, or pustule that may ulcerate (sporotrichotic chancre), but multiple sites of inoculation are possible. Subsequent lesions may appear in a linear distribution along a regional lymphatic path (sporotrichoid spread). Systemic symptoms and regional lymphadenopathy are uncommon and usually are mild.

The second most common clinical manifestation is the fixed cutaneous form, typically affecting the face, neck, trunk, or legs with a single papule, nodule, or verrucous lesion with no lymphangitic spread.⁷ Usually confined to the inoculation site, the primary lesion may be accompanied by satellite lesions and often presents a diagnostic challenge.

Disseminated sporotrichosis (either cutaneous or systemic) is rare. Disseminated cutaneous sporotrichosis manifests with multiple noncontiguous skin lesions caused by lymphatic and possible hematogenous spread. Lesions may include a combination of papules, pustules, follicular eruptions, crusted plaques, and ulcers that may mimic other systemic infections. Immunoreactive changes such as erythema nodosum, erythema multiforme, or arthritis may accompany skin lesions, most commonly with S brasiliensis infections. Nearly 10% of S brasiliensis infections involve the ocular adnexa, and Parinaud oculoglandular syndrome is commonly described in cases reported in Brazil.^42,43 Disseminated disease usually occurs in immunocompromised hosts; however, despite a focus on HIV co-infection,^8,44 prior epidemiologic research has suggested that diabetes and alcoholism are the most common predisposing factors.⁴⁵ Systemic disseminated sporotrichosis by definition affects at least 2 body systems, most commonly the central nervous system, lungs, and musculoskeletal system (including joints and bone marrow).⁴⁵

Extracutaneous sporotrichosis is rare and often is difficult to diagnose. Risk factors include chronic obstructive pulmonary disease, alcoholism, use of steroid medications, AIDS, solid organ transplantation, and use of tumor necrosis factor α inhibitors. It usually affects bony structures through hematogenous spread in immunocompromised hosts and is associated with a high risk for osteomyelitis due to delayed diagnosis.²

Clinical progression of sporotrichosis usually is slow, and lesions may persist for months or years if untreated. Sporotrichosis should always be considered for atypical, persistent, or treatment-resistant manifestations of nodular or ulcerated skin lesions in endemic regions or acute illness with these symptoms following exposure. Preventing secondary bacterial infection is an important consideration as it can exacerbate disease severity, extend the treatment duration, prolong hospitalization, and increase mortality risk.⁴⁶

Diagnosis

In regions endemic for S brasiliensis, it may be acceptable to commence treatment on clinical suspicion without a definitive diagnosis,²¹ but caution is necessary, as lesions easily can be mistaken for other conditions such as Mycobacterium marinum infections (sporotrichoid lesions) or cutaneous leishmaniasis. Limited availability of molecular diagnostic tools in routine clinical laboratories affects the diagnosis of sporotrichosis and species identification. Direct microscopy on a 10% to 30% potassium hydroxide wet mount has low diagnostic sensitivity and is not recommended⁴⁷; findings typically include cigar-shaped yeast cells (eFigure 1). Biopsy and histopathology also are useful, although in many infections (other than those due to S brasiliensis) there are very few detectable organisms in the tissue. Fluorescent staining of fungi with optical brighteners (eg, Calcofluor, Blankophor) is a useful technique with high sensitivity in clinical specimens on histopathologic and direct examination.⁴⁸

Fungal culture has higher sensitivity and specificity than microscopy and is the gold-standard approach for diagnosis of sporotrichosis (eFigure 2); however, culture cannot differentiate between Sporothrix species and may take more than a month to yield a positive result.⁷ No reliable serologic test for sporotrichosis has been validated, and a standardized antigen assay currently is unavailable.⁴⁹ Serology may be more useful for patients who present with systemic disease or have persistently negative culture results despite a high index of suspicion. 

A recent study evaluated the effectiveness of a lateral flow assay for detecting anti-Sporothrix antibodies, demonstrating the potential for its use as a rapid diagnostic test.⁵⁰ Investigating different molecular methods to increase the sensitivity and specificity of diagnosis and distinguish Sporothrix species has been a focus of recent research, with a preference for polymerase chain reaction (PCR)–based genotypic methods.^13,51 Recent advances in diagnostic testing include the development of multiplex PCR,⁵² culture-independent PCR techniques,⁵³ and matrix-assisted laser desorption/ionization–time of flight mass spectrometry,⁵⁴ each with varying clinical and practical applicability. Specialized testing can be beneficial for patients who have a poor therapeutic response to standard treatment, guide antifungal treatment choices, and identify epidemiologic disease and transmission patterns.²¹

Although rarely performed, antifungal susceptibility testing may be useful in guiding therapy to improve patient outcomes, particularly in the context of treatment failure, which has been documented with isolates exhibiting high minimal inhibitory concentrations (MICs) to first-line therapy and a poor clinical response.^55,56 Proposed mechanisms of resistance include increased cellular melanin ­production, which protects against oxidative stress and reduces antifungal activity.⁵⁶ Antifungal susceptibility profiles for therapeutics vary across Sporothrix species; for example, S brasiliensis generally shows lower MICs to itraconazole and terbinafine compared with S schenckii and S globosa, and S schenckii has shown a high MIC to itraconazole, as reflected in MIC distribution studies and epidemiologic cutoff values for antifungal agents.^55,57-59 However, specific breakpoints for different Sporothrix species have not been determined.⁶⁰ Robust clinical studies are needed to determine the correlation of in vitro MICs to clinical outcomes to assess the utility of antifungal susceptibility testing for Sporothrix species.

Management

Treatment of sporotrichosis is guided by clinical presentation, host immune status, and species identification. Management can be challenging in cases with an atypical or delayed diagnosis and limited access to molecular testing methods. Itraconazole is the first-line therapy for management of cutaneous sporotrichosis. It is regarded as safe, effective, well tolerated, and easily administered, with doses ranging from 100 mg in mild cases to 400 mg (with daily or twice-daily dosing).⁶¹ Treatment usually is for 3 to 6 months and should continue for 1 month after complete clinical resolution is achieved⁶²; however, some cases of S brasiliensis infection require longer treatment, and complex or disseminated cases may require therapy for up to 12 months.⁶¹ Itraconazole is contraindicated in pregnancy and has many drug interactions (through cytochrome P450 inhibition) that may preclude administration, particularly in elderly populations. Therapeutic drug monitoring is recommended for prolonged or high-dose therapy, with periodic liver function testing to reduce the risk for toxicity. Itraconazole should be administered with food, and concurrent use of antacids or proton pump inhibitors should be avoided.⁶¹

Oral terbinafine (250 mg daily) can be considered as an effective alternative to treat cutaneous disease.⁶³ Particularly in resource-limited settings, potassium iodide is an affordable and effective treatment for cutaneous sporotrichosis, administered as a saturated oral solution,⁶⁴ but due to adverse effects such as severe nausea, the daily dose should be increased slowly each day to ensure tolerance.

Amphotericin B is the treatment of choice for severe and treatment-resistant cases of sporotrichosis as well as for immunocompromised patients.^21,61 In patients with HIV, a longer treatment course is recommended with oversight from an infectious diseases specialist and usually is followed by a 12-month course of itraconazole after completion of initial therapy.⁶¹ Surgical excision infrequently is recommended but can be used in combination with another treatment modality and may be useful with a slow or incomplete response to medical therapy. Thermotherapy involves direct application of heat to cutaneous lesions and may be considered for small and localized lesions, particularly if antifungal agents are contraindicated or poorly tolerated.⁶¹ Public health measures include promoting case detection through practitioner education and patient awareness in endemic regions, as well as zoonotic control of infected animals to manage sporotrichosis.

Final Thoughts

Sporotrichosis is a fungal infection with growing public health significance. While the global disease burden is unknown, rising case numbers and geographic spread likely reflect a complex interaction between humans, the environment, and animals, exemplified by the spread of feline-associated infection due to S brasiliensis in South America.²⁸ Cases of S brasiliensis infection after importation of an affected cat have been detected outside South America, and clinicians should be alert for introduction to the United States. Strengthening genotypic and phenotypic diagnostic capabilities will allow species identification and guide treatment and management. Disease surveillance and operational research will inform public health approaches to control sporotrichosis worldwide.

THE DIAGNOSIS: Kaposi Varicelliform Eruption

Genital erosions tested positive for herpes simplex virus (HSV) 2 via PCR, confirming a Kaposi varicelliform eruption (KVE) in a patient with mycosis fungoides. The medical team began antiviral therapy with intravenous (IV) acyclovir; however, susceptibility testing during the hospital admission confirmed acyclovir resistance, requiring a transition to cidofovir cream 1% and IV foscarnet.¹ Subsequent concerns by the care team about chemical burns, dysuria, and renal impairment led to discontinuation of both the cidofovir and foscarnet, considerably narrowing the treatment options.¹ The patient’s condition was complicated by polymicrobial bacteremia. Additionally, worsening acidosis and acute kidney injury required initiation of continuous renal replacement therapy.¹ Considering these conditions, the patient was enrolled in a promising clinical trial for pritelivir, a novel antiviral medication; however, due to the development of oliguria and the progression of renal failure, this course of treatment had to be discontinued. Faced with potential viral encephalitis, the infectious disease team concluded that, despite previous adverse reactions, resumption of IV foscarnet treatment would present more benefits than risks, given the patient’s critical situation.¹

Mycosis fungoides (MF) is a slowly progressive cutaneous T-cell lymphoma of CD4+ cells that primarily affects the skin. Clinically, it often is characterized by pruritic scaly patches or plaques with sharply demarcated borders, the enduring nature of which consistently poses a therapeutic challenge due to their noted resistance to preliminary lines of treatment. Presently, potential cures are limited to allogeneic stem cell transplantation and unilesional radiotherapy for advanced MF; however, no treatment has been found to notably improve survival rates.¹ Mycosis fungoides can result in various complications including diffuse spread of a skin infection caused by HSV, known as KVE.¹ Kaposi varicelliform eruption usually manifests clinically with painful skin vesicles that often are accompanied by systemic signs such as fever and malaise. The vesicles rapidly progress into pustules or erosions, predominantly affecting regions such as the head, neck, groin, and upper torso (Figure 1).² Kaposi varicelliform eruption is considered a dermatologic emergency due to its potential to precipitate serious complications such as life-threatening secondary bacterial infection, HSV viremia, and multiorgan involvement; it also carries the risk of instigating ocular complications, such as keratitis, conjunctivitis, blepharitis, uveitis, and potential vision loss.²

Kaposi varicelliform eruption usually is diagnosed through clinical examination supported by polymerase chain reaction, viral culture, histopathology, HSV serology, and Tzanck smear.² The differential diagnosis includes varicella, atypical varicella, herpes genitalis, herpes zoster, allergic or irritant contact dermatitis, or MF, which may result in painful skin ulcers.^2-4 If an HSV superinfection is suspected, a polymerase chain reaction test ideally should be conducted within the first 72 hours of symptom onset.² Herpes simplex virus infection may be reinforced by histologic features such as intraepidermal blistering, acantholysis, keratinocyte ballooning degeneration, and multinuclear giant cells with intranuclear inclusions. Given its severe nature, immediate empiric antiviral treatment for KVE is essential, even while awaiting confirmatory tests. The recommended treatment protocol involves acyclovir (400 mg orally 3 times daily or 10 mg/kg IV) or valacyclovir (500 mg orally twice daily), continued until KVE resolves.²

Herpes genitalis caused by HSV-2 is estimated to affect approximately 45 million adults in the United States.² First-line treatment for HSV-2 includes acyclovir and its derivatives, which are viral nucleoside analogs that inhibit viral DNA polymerases.^5,6 However, over the past 2 decades, increasing HSV resistance to acyclovir and its derivatives has been noted among immunocompromised patients.^5,6 Second-line agents, such as IV foscarnet and cidofovir, require close laboratory monitoring for nephrotoxicity and are contraindicated in those with renal insufficiency, thus limiting their use.⁵ To combat acyclovir resistance, novel antivirals such as pritelivir are being developed. Pritelivir targets the HSV helicase-primase complex and has been shown to outperform acyclovir in in-vitro animal models.⁷ Due to its unique mechanism of action (Figure 2), pritelivir is effective against acyclovir-resistant HSV strains, and clinical trials suggest its serum half-life may allow for daily dosing. A phase 2 study showed pritelivir reduced viral shedding days, sped up genital lesion healing in adults infected with HSV-2, and exhibited a good safety profile.⁷ Our patient participated in ongoing open-label trials of pritelivir that aimed to assess its efficacy and safety in immunocompromised patients. Given the limited alternative treatments for acyclovir-resistant HSV-2, clinicians need to stay updated on antiviral agents under development.

THE DIAGNOSIS: Kaposi Varicelliform Eruption

Genital erosions tested positive for herpes simplex virus (HSV) 2 via PCR, confirming a Kaposi varicelliform eruption (KVE) in a patient with mycosis fungoides. The medical team began antiviral therapy with intravenous (IV) acyclovir; however, susceptibility testing during the hospital admission confirmed acyclovir resistance, requiring a transition to cidofovir cream 1% and IV foscarnet.¹ Subsequent concerns by the care team about chemical burns, dysuria, and renal impairment led to discontinuation of both the cidofovir and foscarnet, considerably narrowing the treatment options.¹ The patient’s condition was complicated by polymicrobial bacteremia. Additionally, worsening acidosis and acute kidney injury required initiation of continuous renal replacement therapy.¹ Considering these conditions, the patient was enrolled in a promising clinical trial for pritelivir, a novel antiviral medication; however, due to the development of oliguria and the progression of renal failure, this course of treatment had to be discontinued. Faced with potential viral encephalitis, the infectious disease team concluded that, despite previous adverse reactions, resumption of IV foscarnet treatment would present more benefits than risks, given the patient’s critical situation.¹

Mycosis fungoides (MF) is a slowly progressive cutaneous T-cell lymphoma of CD4+ cells that primarily affects the skin. Clinically, it often is characterized by pruritic scaly patches or plaques with sharply demarcated borders, the enduring nature of which consistently poses a therapeutic challenge due to their noted resistance to preliminary lines of treatment. Presently, potential cures are limited to allogeneic stem cell transplantation and unilesional radiotherapy for advanced MF; however, no treatment has been found to notably improve survival rates.¹ Mycosis fungoides can result in various complications including diffuse spread of a skin infection caused by HSV, known as KVE.¹ Kaposi varicelliform eruption usually manifests clinically with painful skin vesicles that often are accompanied by systemic signs such as fever and malaise. The vesicles rapidly progress into pustules or erosions, predominantly affecting regions such as the head, neck, groin, and upper torso (Figure 1).² Kaposi varicelliform eruption is considered a dermatologic emergency due to its potential to precipitate serious complications such as life-threatening secondary bacterial infection, HSV viremia, and multiorgan involvement; it also carries the risk of instigating ocular complications, such as keratitis, conjunctivitis, blepharitis, uveitis, and potential vision loss.²

Kaposi varicelliform eruption usually is diagnosed through clinical examination supported by polymerase chain reaction, viral culture, histopathology, HSV serology, and Tzanck smear.² The differential diagnosis includes varicella, atypical varicella, herpes genitalis, herpes zoster, allergic or irritant contact dermatitis, or MF, which may result in painful skin ulcers.^2-4 If an HSV superinfection is suspected, a polymerase chain reaction test ideally should be conducted within the first 72 hours of symptom onset.² Herpes simplex virus infection may be reinforced by histologic features such as intraepidermal blistering, acantholysis, keratinocyte ballooning degeneration, and multinuclear giant cells with intranuclear inclusions. Given its severe nature, immediate empiric antiviral treatment for KVE is essential, even while awaiting confirmatory tests. The recommended treatment protocol involves acyclovir (400 mg orally 3 times daily or 10 mg/kg IV) or valacyclovir (500 mg orally twice daily), continued until KVE resolves.²

Herpes genitalis caused by HSV-2 is estimated to affect approximately 45 million adults in the United States.² First-line treatment for HSV-2 includes acyclovir and its derivatives, which are viral nucleoside analogs that inhibit viral DNA polymerases.^5,6 However, over the past 2 decades, increasing HSV resistance to acyclovir and its derivatives has been noted among immunocompromised patients.^5,6 Second-line agents, such as IV foscarnet and cidofovir, require close laboratory monitoring for nephrotoxicity and are contraindicated in those with renal insufficiency, thus limiting their use.⁵ To combat acyclovir resistance, novel antivirals such as pritelivir are being developed. Pritelivir targets the HSV helicase-primase complex and has been shown to outperform acyclovir in in-vitro animal models.⁷ Due to its unique mechanism of action (Figure 2), pritelivir is effective against acyclovir-resistant HSV strains, and clinical trials suggest its serum half-life may allow for daily dosing. A phase 2 study showed pritelivir reduced viral shedding days, sped up genital lesion healing in adults infected with HSV-2, and exhibited a good safety profile.⁷ Our patient participated in ongoing open-label trials of pritelivir that aimed to assess its efficacy and safety in immunocompromised patients. Given the limited alternative treatments for acyclovir-resistant HSV-2, clinicians need to stay updated on antiviral agents under development.

THE DIAGNOSIS: Kaposi Varicelliform Eruption

Genital erosions tested positive for herpes simplex virus (HSV) 2 via PCR, confirming a Kaposi varicelliform eruption (KVE) in a patient with mycosis fungoides. The medical team began antiviral therapy with intravenous (IV) acyclovir; however, susceptibility testing during the hospital admission confirmed acyclovir resistance, requiring a transition to cidofovir cream 1% and IV foscarnet.¹ Subsequent concerns by the care team about chemical burns, dysuria, and renal impairment led to discontinuation of both the cidofovir and foscarnet, considerably narrowing the treatment options.¹ The patient’s condition was complicated by polymicrobial bacteremia. Additionally, worsening acidosis and acute kidney injury required initiation of continuous renal replacement therapy.¹ Considering these conditions, the patient was enrolled in a promising clinical trial for pritelivir, a novel antiviral medication; however, due to the development of oliguria and the progression of renal failure, this course of treatment had to be discontinued. Faced with potential viral encephalitis, the infectious disease team concluded that, despite previous adverse reactions, resumption of IV foscarnet treatment would present more benefits than risks, given the patient’s critical situation.¹

Mycosis fungoides (MF) is a slowly progressive cutaneous T-cell lymphoma of CD4+ cells that primarily affects the skin. Clinically, it often is characterized by pruritic scaly patches or plaques with sharply demarcated borders, the enduring nature of which consistently poses a therapeutic challenge due to their noted resistance to preliminary lines of treatment. Presently, potential cures are limited to allogeneic stem cell transplantation and unilesional radiotherapy for advanced MF; however, no treatment has been found to notably improve survival rates.¹ Mycosis fungoides can result in various complications including diffuse spread of a skin infection caused by HSV, known as KVE.¹ Kaposi varicelliform eruption usually manifests clinically with painful skin vesicles that often are accompanied by systemic signs such as fever and malaise. The vesicles rapidly progress into pustules or erosions, predominantly affecting regions such as the head, neck, groin, and upper torso (Figure 1).² Kaposi varicelliform eruption is considered a dermatologic emergency due to its potential to precipitate serious complications such as life-threatening secondary bacterial infection, HSV viremia, and multiorgan involvement; it also carries the risk of instigating ocular complications, such as keratitis, conjunctivitis, blepharitis, uveitis, and potential vision loss.²

Kaposi varicelliform eruption usually is diagnosed through clinical examination supported by polymerase chain reaction, viral culture, histopathology, HSV serology, and Tzanck smear.² The differential diagnosis includes varicella, atypical varicella, herpes genitalis, herpes zoster, allergic or irritant contact dermatitis, or MF, which may result in painful skin ulcers.^2-4 If an HSV superinfection is suspected, a polymerase chain reaction test ideally should be conducted within the first 72 hours of symptom onset.² Herpes simplex virus infection may be reinforced by histologic features such as intraepidermal blistering, acantholysis, keratinocyte ballooning degeneration, and multinuclear giant cells with intranuclear inclusions. Given its severe nature, immediate empiric antiviral treatment for KVE is essential, even while awaiting confirmatory tests. The recommended treatment protocol involves acyclovir (400 mg orally 3 times daily or 10 mg/kg IV) or valacyclovir (500 mg orally twice daily), continued until KVE resolves.²

Herpes genitalis caused by HSV-2 is estimated to affect approximately 45 million adults in the United States.² First-line treatment for HSV-2 includes acyclovir and its derivatives, which are viral nucleoside analogs that inhibit viral DNA polymerases.^5,6 However, over the past 2 decades, increasing HSV resistance to acyclovir and its derivatives has been noted among immunocompromised patients.^5,6 Second-line agents, such as IV foscarnet and cidofovir, require close laboratory monitoring for nephrotoxicity and are contraindicated in those with renal insufficiency, thus limiting their use.⁵ To combat acyclovir resistance, novel antivirals such as pritelivir are being developed. Pritelivir targets the HSV helicase-primase complex and has been shown to outperform acyclovir in in-vitro animal models.⁷ Due to its unique mechanism of action (Figure 2), pritelivir is effective against acyclovir-resistant HSV strains, and clinical trials suggest its serum half-life may allow for daily dosing. A phase 2 study showed pritelivir reduced viral shedding days, sped up genital lesion healing in adults infected with HSV-2, and exhibited a good safety profile.⁷ Our patient participated in ongoing open-label trials of pritelivir that aimed to assess its efficacy and safety in immunocompromised patients. Given the limited alternative treatments for acyclovir-resistant HSV-2, clinicians need to stay updated on antiviral agents under development.