Infectious Diseases

Peering through his microscope in 1910, Franco-Canadian microbiologist Félix d’Hérelle noticed some “clear spots” in his bacterial cultures, an anomaly that turned out to be viruses preying on the bacteria. Years later, Mr. d’Hérelle would come to use these viruses, which he called bacteriophages, to treat patients plagued with dysentery after World War I.

In the decades that followed, Mr. d’Hérelle and others used this phage therapy to treat bubonic plague and other bacterial infections until the technique fell into disuse after the widespread adoption of antibiotics in the 1940s.

But now, with bacteria evolving resistance to more and more antibiotics, phage therapy is drawing a second look from researchers — sometimes with a novel twist. Instead of simply using the phages to kill bacteria directly, the new strategy aims to catch the bacteria in an evolutionary dilemma — one in which they cannot evade phages and antibiotics simultaneously.

This plan, which uses something called “phage steering,” has shown promising results in initial tests, but the scope of its usefulness remains to be proven.

There’s certainly need to find new ways to respond to bacterial infections. More than 70% of hospital-acquired bacterial infections in the United States are resistant to at least one type of antibiotic. And some pathogens, such as Acinetobacter, Pseudomonas, Escherichia coli, and Klebsiella — classified by the World Health Organization as some of the biggest threats to human health — are resistant to multiple antibiotics. In 2019, antibacterial resistance was linked to 4.95 million deaths globally, heightening the call for more effective treatment options.

One of the ways that bacteria can evolve resistance to antibiotics is by using structures in their membranes that are designed to move unwanted molecules out of the cell. By modifying these “efflux pumps” to recognize the antibiotic, bacteria can eliminate the drug before it poisons them.

As it turns out, some phages appear to use these same efflux pumps to invade the bacterial cell. The phage presumably attaches its tail to the outer portion of the pump protein, like a key slipping into a lock, and then injects its genetic material into the cell. This lucky coincidence led Paul Turner, PhD, an evolutionary biologist at Yale University, New Haven, Connecticut, to suggest that treating a patient with phages and antibiotics simultaneously could trap bacteria in a no-win situation: If they evolve to modify their efflux pumps so the phage can’t bind, the pumps will no longer expel antibiotics, and the bacteria will lose their resistance. But if they retain their antibiotic resistance, the phages will kill them, as Dr. Turner and colleagues explained in the 2023 Annual Review of Virology.

The result, in other words, is a two-pronged attack, said Michael Hochberg, PhD, an evolutionary biologist at the French National Centre for Scientific Research who studies how to prevent the evolution of bacterial resistance. “It’s kind of like a crisscross effect.” The same principle can target other bacterial molecules that play a dual role in resistance to viruses and antibiotics.

Turner tested this hypothesis on multidrug-resistant Pseudomonas aeruginosa, which causes dangerous infections, especially in healthcare settings. This bacterium has four efflux pumps involved in antibiotic resistance, and Dr. Turner predicted that if he could find a phage that used one of the pumps as a way into the cell, the bacterium would be forced to slam the door on the phage by mutating the receptor — thereby impeding its ability to pump out antibiotics.

Sampling from the environment, Dr. Turner’s team collected 42 phage strains that infect P aeruginosa. Out of all the phages, one, OMKO1, bound to an efflux pump, making it the perfect candidate for the experiment.

The researchers then cultured antibiotic-resistant P aeruginosa together with OMKO1, hoping this would force the bacterium to modify its efflux pump to resist the phage. They exposed these phage-resistant bacteria, as well as their normal, phage-sensitive counterparts, to four antibiotics the bacteria had been resistant to: tetracycline, erythromycin, ciprofloxacin, and ceftazidime.

As the theory predicted, the bacteria that had evolved resistance to the phage were more sensitive to the antibiotics than those that had not been exposed to the phage. This suggests that the bacteria had, indeed, been forced to lose their antibiotic resistance through their need to fight off the phage.

Other researchers have also shown that phage steering can resensitize bacteria to common antibiotics they’d become resistant to. One study, by an international research team, showed that a phage called Phab24 can be used to restore sensitivity to the antibiotic colistin in Acinetobacter baumannii, which causes life-threatening diseases.

In a second study, researchers at Monash University in Australia sampled infectious bacteria from patients. They found that several phages, including strains known as phi-FG02 and phi-CO01, were already present in some of the samples, and that A baumannii bacteria exposed to the phages had inactivated a gene that helps create the microbe’s important outer layer, or capsule. This layer serves as the entry point for the phages, but it also helps the bacterium to form biofilms that keep out antibiotics — so removing the layer rendered A baumannii susceptible to several antibiotics that it was previously resistant to.

In a third study, researchers from the University of Liverpool discovered that, when a P aeruginosa strain that was resistant to all antibiotics was exposed to phages, the bacterium became sensitive to two antibiotics that were otherwise considered ineffective against P aeruginosa.

Dr. Turner’s team has used phage steering in dozens of cases of personalized therapy in clinical settings, said Benjamin Chan, PhD, a microbiologist at Yale University who works with Dr. Turner. The results, many still unpublished, have been promising so far. Nonrespiratory infections are relatively easy to clear off, and lung infections, which the phage steering approach wouldn’t be expected to eradicate completely, often show some improvement.

“I would say that we have been quite successful in using phage steering to treat difficult-to-manage infections, reducing antimicrobial resistance in many cases,” he said. But he notes that it is sometimes difficult to determine whether phage steering really was responsible for the cures.
 

Devil in the details

Phage therapy may not work for all antibiotic-resistant bacteria, said molecular biologist Graham Hatfull, PhD, of the University of Pittsburgh in Pennsylvania. That’s because phages are very host specific, and for most phages, no one knows what target they bind to on the bacterial cell surface. For phage steering to work against antibiotic resistance, the phage has to bind to a molecule that’s involved in that resistance — and it’s not clear how often that fortuitous coincidence occurs.

Jason Gill, PhD, who studies bacteriophage biology at Texas A&M University, College Station, said that it is not easy to predict if a phage will induce antibiotic sensitivity. So you always have to hunt for the right virus each time.

Dr. Gill knows from experience how complicated the approach can get. He was part of a team of researchers and doctors who used phages to treat a patient with a multidrug-resistant A baumannii infection. Less than 4 days after the team administered phages intravenously and through the skin, the patient woke up from a coma and became responsive to the previously ineffective antibiotic minocycline — a striking success.

But when Dr. Gill tried a similar experiment in cell cultures, he got a different result. The A baumannii developed resistance to the phages, but they also maintained their resistance to minocycline. “There’s not a complete mechanistic understanding,” said Dr. Gill. “The linkage between phage resistance and antibiotic sensitivity probably varies by bacterial strain, phage and antibiotic.” That means phage steering may not always work.

Dr. Turner, for his part, pointed out another potential problem: That phages could work too well. If phage therapy kills large amounts of bacteria and deposits their remains in the bloodstream quickly, for example, this could trigger septic shock in patients. Scientists do not yet know how to address this problem.

Another concern is that doctors have less precise control over phages than antibiotics. “Phages can mutate, they can adapt, they have a genome,” said Dr. Hochberg. Safety concerns, he notes, are one factor inhibiting the routine use of phage therapy in countries like the United States, restricting it to case-by-case applications such as Dr. Turner and Dr. Chan’s.

Phage therapy may have been too high-tech for the 1940s, and even today, scientists grapple with how to use it. What we need now, said Dr. Turner, are rigorous experiments that will teach us how to make it work.

This article originally appeared in Knowable Magazine on September 09, 2024. Knowable Magazine is an independent journalistic endeavor from Annual Reviews, a nonprofit publisher dedicated to synthesizing and integrating knowledge for the progress of science and the benefit of society. Sign up for Knowable Magazine’s newsletter. A version of this article appeared on Medscape.com.

Peering through his microscope in 1910, Franco-Canadian microbiologist Félix d’Hérelle noticed some “clear spots” in his bacterial cultures, an anomaly that turned out to be viruses preying on the bacteria. Years later, Mr. d’Hérelle would come to use these viruses, which he called bacteriophages, to treat patients plagued with dysentery after World War I.

In the decades that followed, Mr. d’Hérelle and others used this phage therapy to treat bubonic plague and other bacterial infections until the technique fell into disuse after the widespread adoption of antibiotics in the 1940s.

But now, with bacteria evolving resistance to more and more antibiotics, phage therapy is drawing a second look from researchers — sometimes with a novel twist. Instead of simply using the phages to kill bacteria directly, the new strategy aims to catch the bacteria in an evolutionary dilemma — one in which they cannot evade phages and antibiotics simultaneously.

This plan, which uses something called “phage steering,” has shown promising results in initial tests, but the scope of its usefulness remains to be proven.

There’s certainly need to find new ways to respond to bacterial infections. More than 70% of hospital-acquired bacterial infections in the United States are resistant to at least one type of antibiotic. And some pathogens, such as Acinetobacter, Pseudomonas, Escherichia coli, and Klebsiella — classified by the World Health Organization as some of the biggest threats to human health — are resistant to multiple antibiotics. In 2019, antibacterial resistance was linked to 4.95 million deaths globally, heightening the call for more effective treatment options.

One of the ways that bacteria can evolve resistance to antibiotics is by using structures in their membranes that are designed to move unwanted molecules out of the cell. By modifying these “efflux pumps” to recognize the antibiotic, bacteria can eliminate the drug before it poisons them.

As it turns out, some phages appear to use these same efflux pumps to invade the bacterial cell. The phage presumably attaches its tail to the outer portion of the pump protein, like a key slipping into a lock, and then injects its genetic material into the cell. This lucky coincidence led Paul Turner, PhD, an evolutionary biologist at Yale University, New Haven, Connecticut, to suggest that treating a patient with phages and antibiotics simultaneously could trap bacteria in a no-win situation: If they evolve to modify their efflux pumps so the phage can’t bind, the pumps will no longer expel antibiotics, and the bacteria will lose their resistance. But if they retain their antibiotic resistance, the phages will kill them, as Dr. Turner and colleagues explained in the 2023 Annual Review of Virology.

The result, in other words, is a two-pronged attack, said Michael Hochberg, PhD, an evolutionary biologist at the French National Centre for Scientific Research who studies how to prevent the evolution of bacterial resistance. “It’s kind of like a crisscross effect.” The same principle can target other bacterial molecules that play a dual role in resistance to viruses and antibiotics.

Turner tested this hypothesis on multidrug-resistant Pseudomonas aeruginosa, which causes dangerous infections, especially in healthcare settings. This bacterium has four efflux pumps involved in antibiotic resistance, and Dr. Turner predicted that if he could find a phage that used one of the pumps as a way into the cell, the bacterium would be forced to slam the door on the phage by mutating the receptor — thereby impeding its ability to pump out antibiotics.

Sampling from the environment, Dr. Turner’s team collected 42 phage strains that infect P aeruginosa. Out of all the phages, one, OMKO1, bound to an efflux pump, making it the perfect candidate for the experiment.

The researchers then cultured antibiotic-resistant P aeruginosa together with OMKO1, hoping this would force the bacterium to modify its efflux pump to resist the phage. They exposed these phage-resistant bacteria, as well as their normal, phage-sensitive counterparts, to four antibiotics the bacteria had been resistant to: tetracycline, erythromycin, ciprofloxacin, and ceftazidime.

As the theory predicted, the bacteria that had evolved resistance to the phage were more sensitive to the antibiotics than those that had not been exposed to the phage. This suggests that the bacteria had, indeed, been forced to lose their antibiotic resistance through their need to fight off the phage.

Other researchers have also shown that phage steering can resensitize bacteria to common antibiotics they’d become resistant to. One study, by an international research team, showed that a phage called Phab24 can be used to restore sensitivity to the antibiotic colistin in Acinetobacter baumannii, which causes life-threatening diseases.

In a second study, researchers at Monash University in Australia sampled infectious bacteria from patients. They found that several phages, including strains known as phi-FG02 and phi-CO01, were already present in some of the samples, and that A baumannii bacteria exposed to the phages had inactivated a gene that helps create the microbe’s important outer layer, or capsule. This layer serves as the entry point for the phages, but it also helps the bacterium to form biofilms that keep out antibiotics — so removing the layer rendered A baumannii susceptible to several antibiotics that it was previously resistant to.

In a third study, researchers from the University of Liverpool discovered that, when a P aeruginosa strain that was resistant to all antibiotics was exposed to phages, the bacterium became sensitive to two antibiotics that were otherwise considered ineffective against P aeruginosa.

Dr. Turner’s team has used phage steering in dozens of cases of personalized therapy in clinical settings, said Benjamin Chan, PhD, a microbiologist at Yale University who works with Dr. Turner. The results, many still unpublished, have been promising so far. Nonrespiratory infections are relatively easy to clear off, and lung infections, which the phage steering approach wouldn’t be expected to eradicate completely, often show some improvement.

“I would say that we have been quite successful in using phage steering to treat difficult-to-manage infections, reducing antimicrobial resistance in many cases,” he said. But he notes that it is sometimes difficult to determine whether phage steering really was responsible for the cures.
 

Devil in the details

Phage therapy may not work for all antibiotic-resistant bacteria, said molecular biologist Graham Hatfull, PhD, of the University of Pittsburgh in Pennsylvania. That’s because phages are very host specific, and for most phages, no one knows what target they bind to on the bacterial cell surface. For phage steering to work against antibiotic resistance, the phage has to bind to a molecule that’s involved in that resistance — and it’s not clear how often that fortuitous coincidence occurs.

Jason Gill, PhD, who studies bacteriophage biology at Texas A&M University, College Station, said that it is not easy to predict if a phage will induce antibiotic sensitivity. So you always have to hunt for the right virus each time.

Dr. Gill knows from experience how complicated the approach can get. He was part of a team of researchers and doctors who used phages to treat a patient with a multidrug-resistant A baumannii infection. Less than 4 days after the team administered phages intravenously and through the skin, the patient woke up from a coma and became responsive to the previously ineffective antibiotic minocycline — a striking success.

But when Dr. Gill tried a similar experiment in cell cultures, he got a different result. The A baumannii developed resistance to the phages, but they also maintained their resistance to minocycline. “There’s not a complete mechanistic understanding,” said Dr. Gill. “The linkage between phage resistance and antibiotic sensitivity probably varies by bacterial strain, phage and antibiotic.” That means phage steering may not always work.

Dr. Turner, for his part, pointed out another potential problem: That phages could work too well. If phage therapy kills large amounts of bacteria and deposits their remains in the bloodstream quickly, for example, this could trigger septic shock in patients. Scientists do not yet know how to address this problem.

Another concern is that doctors have less precise control over phages than antibiotics. “Phages can mutate, they can adapt, they have a genome,” said Dr. Hochberg. Safety concerns, he notes, are one factor inhibiting the routine use of phage therapy in countries like the United States, restricting it to case-by-case applications such as Dr. Turner and Dr. Chan’s.

Phage therapy may have been too high-tech for the 1940s, and even today, scientists grapple with how to use it. What we need now, said Dr. Turner, are rigorous experiments that will teach us how to make it work.

This article originally appeared in Knowable Magazine on September 09, 2024. Knowable Magazine is an independent journalistic endeavor from Annual Reviews, a nonprofit publisher dedicated to synthesizing and integrating knowledge for the progress of science and the benefit of society. Sign up for Knowable Magazine’s newsletter. A version of this article appeared on Medscape.com.

Peering through his microscope in 1910, Franco-Canadian microbiologist Félix d’Hérelle noticed some “clear spots” in his bacterial cultures, an anomaly that turned out to be viruses preying on the bacteria. Years later, Mr. d’Hérelle would come to use these viruses, which he called bacteriophages, to treat patients plagued with dysentery after World War I.

In the decades that followed, Mr. d’Hérelle and others used this phage therapy to treat bubonic plague and other bacterial infections until the technique fell into disuse after the widespread adoption of antibiotics in the 1940s.

But now, with bacteria evolving resistance to more and more antibiotics, phage therapy is drawing a second look from researchers — sometimes with a novel twist. Instead of simply using the phages to kill bacteria directly, the new strategy aims to catch the bacteria in an evolutionary dilemma — one in which they cannot evade phages and antibiotics simultaneously.

This plan, which uses something called “phage steering,” has shown promising results in initial tests, but the scope of its usefulness remains to be proven.

There’s certainly need to find new ways to respond to bacterial infections. More than 70% of hospital-acquired bacterial infections in the United States are resistant to at least one type of antibiotic. And some pathogens, such as Acinetobacter, Pseudomonas, Escherichia coli, and Klebsiella — classified by the World Health Organization as some of the biggest threats to human health — are resistant to multiple antibiotics. In 2019, antibacterial resistance was linked to 4.95 million deaths globally, heightening the call for more effective treatment options.

One of the ways that bacteria can evolve resistance to antibiotics is by using structures in their membranes that are designed to move unwanted molecules out of the cell. By modifying these “efflux pumps” to recognize the antibiotic, bacteria can eliminate the drug before it poisons them.

As it turns out, some phages appear to use these same efflux pumps to invade the bacterial cell. The phage presumably attaches its tail to the outer portion of the pump protein, like a key slipping into a lock, and then injects its genetic material into the cell. This lucky coincidence led Paul Turner, PhD, an evolutionary biologist at Yale University, New Haven, Connecticut, to suggest that treating a patient with phages and antibiotics simultaneously could trap bacteria in a no-win situation: If they evolve to modify their efflux pumps so the phage can’t bind, the pumps will no longer expel antibiotics, and the bacteria will lose their resistance. But if they retain their antibiotic resistance, the phages will kill them, as Dr. Turner and colleagues explained in the 2023 Annual Review of Virology.

The result, in other words, is a two-pronged attack, said Michael Hochberg, PhD, an evolutionary biologist at the French National Centre for Scientific Research who studies how to prevent the evolution of bacterial resistance. “It’s kind of like a crisscross effect.” The same principle can target other bacterial molecules that play a dual role in resistance to viruses and antibiotics.

Turner tested this hypothesis on multidrug-resistant Pseudomonas aeruginosa, which causes dangerous infections, especially in healthcare settings. This bacterium has four efflux pumps involved in antibiotic resistance, and Dr. Turner predicted that if he could find a phage that used one of the pumps as a way into the cell, the bacterium would be forced to slam the door on the phage by mutating the receptor — thereby impeding its ability to pump out antibiotics.

Sampling from the environment, Dr. Turner’s team collected 42 phage strains that infect P aeruginosa. Out of all the phages, one, OMKO1, bound to an efflux pump, making it the perfect candidate for the experiment.

The researchers then cultured antibiotic-resistant P aeruginosa together with OMKO1, hoping this would force the bacterium to modify its efflux pump to resist the phage. They exposed these phage-resistant bacteria, as well as their normal, phage-sensitive counterparts, to four antibiotics the bacteria had been resistant to: tetracycline, erythromycin, ciprofloxacin, and ceftazidime.

As the theory predicted, the bacteria that had evolved resistance to the phage were more sensitive to the antibiotics than those that had not been exposed to the phage. This suggests that the bacteria had, indeed, been forced to lose their antibiotic resistance through their need to fight off the phage.

Other researchers have also shown that phage steering can resensitize bacteria to common antibiotics they’d become resistant to. One study, by an international research team, showed that a phage called Phab24 can be used to restore sensitivity to the antibiotic colistin in Acinetobacter baumannii, which causes life-threatening diseases.

In a second study, researchers at Monash University in Australia sampled infectious bacteria from patients. They found that several phages, including strains known as phi-FG02 and phi-CO01, were already present in some of the samples, and that A baumannii bacteria exposed to the phages had inactivated a gene that helps create the microbe’s important outer layer, or capsule. This layer serves as the entry point for the phages, but it also helps the bacterium to form biofilms that keep out antibiotics — so removing the layer rendered A baumannii susceptible to several antibiotics that it was previously resistant to.

In a third study, researchers from the University of Liverpool discovered that, when a P aeruginosa strain that was resistant to all antibiotics was exposed to phages, the bacterium became sensitive to two antibiotics that were otherwise considered ineffective against P aeruginosa.

Dr. Turner’s team has used phage steering in dozens of cases of personalized therapy in clinical settings, said Benjamin Chan, PhD, a microbiologist at Yale University who works with Dr. Turner. The results, many still unpublished, have been promising so far. Nonrespiratory infections are relatively easy to clear off, and lung infections, which the phage steering approach wouldn’t be expected to eradicate completely, often show some improvement.

“I would say that we have been quite successful in using phage steering to treat difficult-to-manage infections, reducing antimicrobial resistance in many cases,” he said. But he notes that it is sometimes difficult to determine whether phage steering really was responsible for the cures.
 

Devil in the details

Phage therapy may not work for all antibiotic-resistant bacteria, said molecular biologist Graham Hatfull, PhD, of the University of Pittsburgh in Pennsylvania. That’s because phages are very host specific, and for most phages, no one knows what target they bind to on the bacterial cell surface. For phage steering to work against antibiotic resistance, the phage has to bind to a molecule that’s involved in that resistance — and it’s not clear how often that fortuitous coincidence occurs.

Jason Gill, PhD, who studies bacteriophage biology at Texas A&M University, College Station, said that it is not easy to predict if a phage will induce antibiotic sensitivity. So you always have to hunt for the right virus each time.

Dr. Gill knows from experience how complicated the approach can get. He was part of a team of researchers and doctors who used phages to treat a patient with a multidrug-resistant A baumannii infection. Less than 4 days after the team administered phages intravenously and through the skin, the patient woke up from a coma and became responsive to the previously ineffective antibiotic minocycline — a striking success.

But when Dr. Gill tried a similar experiment in cell cultures, he got a different result. The A baumannii developed resistance to the phages, but they also maintained their resistance to minocycline. “There’s not a complete mechanistic understanding,” said Dr. Gill. “The linkage between phage resistance and antibiotic sensitivity probably varies by bacterial strain, phage and antibiotic.” That means phage steering may not always work.

Dr. Turner, for his part, pointed out another potential problem: That phages could work too well. If phage therapy kills large amounts of bacteria and deposits their remains in the bloodstream quickly, for example, this could trigger septic shock in patients. Scientists do not yet know how to address this problem.

Another concern is that doctors have less precise control over phages than antibiotics. “Phages can mutate, they can adapt, they have a genome,” said Dr. Hochberg. Safety concerns, he notes, are one factor inhibiting the routine use of phage therapy in countries like the United States, restricting it to case-by-case applications such as Dr. Turner and Dr. Chan’s.

Phage therapy may have been too high-tech for the 1940s, and even today, scientists grapple with how to use it. What we need now, said Dr. Turner, are rigorous experiments that will teach us how to make it work.

This article originally appeared in Knowable Magazine on September 09, 2024. Knowable Magazine is an independent journalistic endeavor from Annual Reviews, a nonprofit publisher dedicated to synthesizing and integrating knowledge for the progress of science and the benefit of society. Sign up for Knowable Magazine’s newsletter. A version of this article appeared on Medscape.com.

Pulmonology Data Trends 2024 is a supplement to CHEST Physician highlighting the latest breakthroughs in pulmonology research and treatments through a series of infographics.

Read more: 

Artificial Intelligence in Sleep Apnea
Ritwick Agrawal, MD, MS, FCCP

RSV Updates: Prophylaxis Approval and Hospitalization for Severe RSV
Riddhi Upadhyay, MD

Biologics in Asthma: Changing the Severe Asthma Paradigm
Shyam Subramanian, MD, FCCP

Updates in COPD Guidelines and Treatment
Dharani K. Narendra, MD, FCCP

Targeted Therapies and Surgical Resection for Lung Cancer: Evolving Treatment Options
Saadia A. Faiz, MD, FCCP

Closing the GAP in Idiopathic Pulmonary Fibrosis
Humayun Anjum, MD, FCCP

Severe Community-Acquired Pneumonia: Diagnostic Criteria, Treatment, and COVID-19
Sujith V. Cherian, MD, FCCP

Pulmonary Hypertension: Comorbidities and Novel Therapies
Mary Jo S. Farmer, MD, PhD, FCCP

The Genetic Side of Interstitial Lung Disease
Priya Balakrishnan, MD, MS, FCCP

Noninvasive Ventilation in Neuromuscular Disease
Sreelatha Naik, MD, FCCP, and Kelly Lobrutto, CRNP

Pulmonology Data Trends 2024 is a supplement to CHEST Physician highlighting the latest breakthroughs in pulmonology research and treatments through a series of infographics.

Read more: 

Artificial Intelligence in Sleep Apnea
Ritwick Agrawal, MD, MS, FCCP

RSV Updates: Prophylaxis Approval and Hospitalization for Severe RSV
Riddhi Upadhyay, MD

Biologics in Asthma: Changing the Severe Asthma Paradigm
Shyam Subramanian, MD, FCCP

Updates in COPD Guidelines and Treatment
Dharani K. Narendra, MD, FCCP

Targeted Therapies and Surgical Resection for Lung Cancer: Evolving Treatment Options
Saadia A. Faiz, MD, FCCP

Closing the GAP in Idiopathic Pulmonary Fibrosis
Humayun Anjum, MD, FCCP

Severe Community-Acquired Pneumonia: Diagnostic Criteria, Treatment, and COVID-19
Sujith V. Cherian, MD, FCCP

Pulmonary Hypertension: Comorbidities and Novel Therapies
Mary Jo S. Farmer, MD, PhD, FCCP

The Genetic Side of Interstitial Lung Disease
Priya Balakrishnan, MD, MS, FCCP

Noninvasive Ventilation in Neuromuscular Disease
Sreelatha Naik, MD, FCCP, and Kelly Lobrutto, CRNP

Pulmonology Data Trends 2024 is a supplement to CHEST Physician highlighting the latest breakthroughs in pulmonology research and treatments through a series of infographics.

Read more: 

Artificial Intelligence in Sleep Apnea
Ritwick Agrawal, MD, MS, FCCP

RSV Updates: Prophylaxis Approval and Hospitalization for Severe RSV
Riddhi Upadhyay, MD

Biologics in Asthma: Changing the Severe Asthma Paradigm
Shyam Subramanian, MD, FCCP

Updates in COPD Guidelines and Treatment
Dharani K. Narendra, MD, FCCP

Targeted Therapies and Surgical Resection for Lung Cancer: Evolving Treatment Options
Saadia A. Faiz, MD, FCCP

Closing the GAP in Idiopathic Pulmonary Fibrosis
Humayun Anjum, MD, FCCP

Severe Community-Acquired Pneumonia: Diagnostic Criteria, Treatment, and COVID-19
Sujith V. Cherian, MD, FCCP

Pulmonary Hypertension: Comorbidities and Novel Therapies
Mary Jo S. Farmer, MD, PhD, FCCP

The Genetic Side of Interstitial Lung Disease
Priya Balakrishnan, MD, MS, FCCP

Noninvasive Ventilation in Neuromuscular Disease
Sreelatha Naik, MD, FCCP, and Kelly Lobrutto, CRNP

TOPLINE: 

Compared with other urine analysis methods, urine Gram stain has a moderate predictive value for detecting gram-negative bacteria in urine culture but does not significantly improve urinary tract infection (UTI) diagnosis in the emergency department (ED).

METHODOLOGY:

• Researchers conducted an observational cohort study at the University Medical Center Groningen in the Netherlands, encompassing 1358 episodes across 1136 patients suspected of having a UTI.
• The study included the following predefined subgroups: patients using urinary catheters and patients with leukopenia (< 4.0×10⁹ leucocytes/L). Urine dipstick nitrite, automated urinalysis, Gram stain, and urine cultures were performed on urine samples collected from patients presenting at the ED.
• The sensitivity and specificity of Gram stain for “many” bacteria (quantified as > 15/high power field) were compared with those of urine dipstick nitrite and automated bacterial counting in urinalysis.

TAKEAWAY:

• The sensitivity and specificity of Gram stain for “many” bacteria were 51.3% and 91.0%, respectively, with an accuracy of 76.8%.
• Gram stain showed a positive predictive value (PPV) of 84.7% for gram-negative rods in urine culture; however, the PPV was only 38.4% for gram-positive cocci.
• In the catheter subgroup, the presence of monomorphic bacteria quantified as “many” had a higher PPV for diagnosing a UTI than the presence of polymorphic bacteria with the same quantification.
• The overall performance of Gram stain in diagnosing a UTI in the ED was comparable to that of automated bacterial counting in urinalysis but better than that of urine dipstick nitrite.

IN PRACTICE:

“With the exception of a moderate prediction of gram-negative bacteria in the UC [urine culture], urine GS [Gram stain] does not improve UTI diagnosis at the ED compared to other urine parameters,” the authors wrote.

SOURCE:

The study was led by Stephanie J.M. Middelkoop, University of Groningen, University Medical Center Groningen, the Netherlands. It was published online on August 16, 2024, in Infectious Diseases.

LIMITATIONS: 

The study’s limitations included a small sample size within the leukopenia subgroup, which may have affected the generalizability of the findings. Additionally, the potential influence of refrigeration of urine samples on bacterial growth could have affected the results. In this study, indwelling catheters were not replaced before urine sample collection, which may have affected the accuracy of UTI diagnosis in patients using catheters.
 

DISCLOSURES:

No conflicts of interest were disclosed by the authors.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.

TOPLINE: 

Compared with other urine analysis methods, urine Gram stain has a moderate predictive value for detecting gram-negative bacteria in urine culture but does not significantly improve urinary tract infection (UTI) diagnosis in the emergency department (ED).

METHODOLOGY:

• Researchers conducted an observational cohort study at the University Medical Center Groningen in the Netherlands, encompassing 1358 episodes across 1136 patients suspected of having a UTI.
• The study included the following predefined subgroups: patients using urinary catheters and patients with leukopenia (< 4.0×10⁹ leucocytes/L). Urine dipstick nitrite, automated urinalysis, Gram stain, and urine cultures were performed on urine samples collected from patients presenting at the ED.
• The sensitivity and specificity of Gram stain for “many” bacteria (quantified as > 15/high power field) were compared with those of urine dipstick nitrite and automated bacterial counting in urinalysis.

TAKEAWAY:

• The sensitivity and specificity of Gram stain for “many” bacteria were 51.3% and 91.0%, respectively, with an accuracy of 76.8%.
• Gram stain showed a positive predictive value (PPV) of 84.7% for gram-negative rods in urine culture; however, the PPV was only 38.4% for gram-positive cocci.
• In the catheter subgroup, the presence of monomorphic bacteria quantified as “many” had a higher PPV for diagnosing a UTI than the presence of polymorphic bacteria with the same quantification.
• The overall performance of Gram stain in diagnosing a UTI in the ED was comparable to that of automated bacterial counting in urinalysis but better than that of urine dipstick nitrite.

IN PRACTICE:

“With the exception of a moderate prediction of gram-negative bacteria in the UC [urine culture], urine GS [Gram stain] does not improve UTI diagnosis at the ED compared to other urine parameters,” the authors wrote.

SOURCE:

The study was led by Stephanie J.M. Middelkoop, University of Groningen, University Medical Center Groningen, the Netherlands. It was published online on August 16, 2024, in Infectious Diseases.

LIMITATIONS: 

The study’s limitations included a small sample size within the leukopenia subgroup, which may have affected the generalizability of the findings. Additionally, the potential influence of refrigeration of urine samples on bacterial growth could have affected the results. In this study, indwelling catheters were not replaced before urine sample collection, which may have affected the accuracy of UTI diagnosis in patients using catheters.
 

DISCLOSURES:

No conflicts of interest were disclosed by the authors.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.

TOPLINE: 

Compared with other urine analysis methods, urine Gram stain has a moderate predictive value for detecting gram-negative bacteria in urine culture but does not significantly improve urinary tract infection (UTI) diagnosis in the emergency department (ED).

METHODOLOGY:

• Researchers conducted an observational cohort study at the University Medical Center Groningen in the Netherlands, encompassing 1358 episodes across 1136 patients suspected of having a UTI.
• The study included the following predefined subgroups: patients using urinary catheters and patients with leukopenia (< 4.0×10⁹ leucocytes/L). Urine dipstick nitrite, automated urinalysis, Gram stain, and urine cultures were performed on urine samples collected from patients presenting at the ED.
• The sensitivity and specificity of Gram stain for “many” bacteria (quantified as > 15/high power field) were compared with those of urine dipstick nitrite and automated bacterial counting in urinalysis.

TAKEAWAY:

• The sensitivity and specificity of Gram stain for “many” bacteria were 51.3% and 91.0%, respectively, with an accuracy of 76.8%.
• Gram stain showed a positive predictive value (PPV) of 84.7% for gram-negative rods in urine culture; however, the PPV was only 38.4% for gram-positive cocci.
• In the catheter subgroup, the presence of monomorphic bacteria quantified as “many” had a higher PPV for diagnosing a UTI than the presence of polymorphic bacteria with the same quantification.
• The overall performance of Gram stain in diagnosing a UTI in the ED was comparable to that of automated bacterial counting in urinalysis but better than that of urine dipstick nitrite.

IN PRACTICE:

“With the exception of a moderate prediction of gram-negative bacteria in the UC [urine culture], urine GS [Gram stain] does not improve UTI diagnosis at the ED compared to other urine parameters,” the authors wrote.

SOURCE:

The study was led by Stephanie J.M. Middelkoop, University of Groningen, University Medical Center Groningen, the Netherlands. It was published online on August 16, 2024, in Infectious Diseases.

LIMITATIONS: 

The study’s limitations included a small sample size within the leukopenia subgroup, which may have affected the generalizability of the findings. Additionally, the potential influence of refrigeration of urine samples on bacterial growth could have affected the results. In this study, indwelling catheters were not replaced before urine sample collection, which may have affected the accuracy of UTI diagnosis in patients using catheters.
 

DISCLOSURES:

No conflicts of interest were disclosed by the authors.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.

Listeriosis during pregnancy, when invasive, can be fatal for the fetus, with a rate of fetal loss or neonatal death of 29%, investigators reported in an article alerting clinicians to this condition.

The article was prompted when the Reproductive Infectious Diseases team at The University of British Columbia in Vancouver, British Columbia, Canada, “received many phone calls from concerned doctors and patients after the plant-based milk recall in early July,” Jeffrey Man Hay Wong, MD, told this news organization. “With such concerns, we updated our British Columbia guidelines for our patients but quickly realized that our recommendations would be useful across the country.”

The article was published online in the Canadian Medical Association Journal.


 

Five Key Points

Dr. Wong and colleagues provided the following five points and recommendations:

First, invasive listeriosis (bacteremia or meningitis) in pregnancy can have major fetal consequences, including fetal loss or neonatal death in 29% of cases. Affected patients can be asymptomatic or experience gastrointestinal symptoms, myalgias, fevers, acute respiratory distress syndrome, or sepsis.

Second, pregnant people should avoid foods at a high risk for Listeria monocytogenes contamination, including unpasteurized dairy products, luncheon meats, refrigerated meat spreads, and prepared salads. They also should stay aware of Health Canada recalls.

Third, it is not necessary to investigate or treat patients who may have ingested contaminated food but are asymptomatic. Listeriosis can present at 2-3 months after exposure because the incubation period can be as long as 70 days.

Fourth, for patients with mild gastroenteritis or flu-like symptoms who may have ingested contaminated food, obtaining blood cultures or starting a 2-week course of oral amoxicillin (500 mg, three times daily) could be considered.

Fifth, for patients with fever and possible exposure to L monocytogenes, blood cultures should be drawn immediately, and high-dose ampicillin should be initiated, along with electronic fetal heart rate monitoring.

“While choosing safer foods in pregnancy is recommended, it is most important to be aware of Health Canada food recalls and pay attention to symptoms if you’ve ingested these foods,” said Dr. Wong. “Working with the BC Centre for Disease Control, our teams are actively monitoring for cases of listeriosis in pregnancy here in British Columbia.

“Thankfully,” he said, “there haven’t been any confirmed cases in British Columbia related to the plant-based milk recall, though the bacteria’s incubation period can be up to 70 days in pregnancy.”
 

No Increase Suspected

Commenting on the article, Khady Diouf, MD, director of global obstetrics and gynecology at Brigham and Women’s Hospital in Boston, said, “It summarizes the main management, which is based mostly on expert opinion.”

US clinicians also should be reminded about listeriosis in pregnancy, she noted, pointing to “helpful guidance” from the American College of Obstetrics and Gynecology.

Although the United States similarly experienced a recent listeriosis outbreak resulting from contaminated deli meats, both Dr. Wong and Dr. Diouf said that these outbreaks do not seem to signal an increase in listeriosis cases overall.

“Food-borne listeriosis seems to come in waves,” said Dr. Wong. “At a public health level, we certainly have better surveillance programs for Listeria infections. In 2023, Health Canada updated its Policy on L monocytogenes in ready-to-eat foods, which emphasizes the good manufacturing practices recommended for food processing environments to identify outbreaks earlier.”

“I think we get these recalls yearly, and this has been the case for as long as I can remember,” Dr. Diouf agreed.

No funding was declared, and the authors declared no relevant financial relationships.

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

Listeriosis during pregnancy, when invasive, can be fatal for the fetus, with a rate of fetal loss or neonatal death of 29%, investigators reported in an article alerting clinicians to this condition.

The article was prompted when the Reproductive Infectious Diseases team at The University of British Columbia in Vancouver, British Columbia, Canada, “received many phone calls from concerned doctors and patients after the plant-based milk recall in early July,” Jeffrey Man Hay Wong, MD, told this news organization. “With such concerns, we updated our British Columbia guidelines for our patients but quickly realized that our recommendations would be useful across the country.”

The article was published online in the Canadian Medical Association Journal.


 

Five Key Points

Dr. Wong and colleagues provided the following five points and recommendations:

First, invasive listeriosis (bacteremia or meningitis) in pregnancy can have major fetal consequences, including fetal loss or neonatal death in 29% of cases. Affected patients can be asymptomatic or experience gastrointestinal symptoms, myalgias, fevers, acute respiratory distress syndrome, or sepsis.

Second, pregnant people should avoid foods at a high risk for Listeria monocytogenes contamination, including unpasteurized dairy products, luncheon meats, refrigerated meat spreads, and prepared salads. They also should stay aware of Health Canada recalls.

Third, it is not necessary to investigate or treat patients who may have ingested contaminated food but are asymptomatic. Listeriosis can present at 2-3 months after exposure because the incubation period can be as long as 70 days.

Fourth, for patients with mild gastroenteritis or flu-like symptoms who may have ingested contaminated food, obtaining blood cultures or starting a 2-week course of oral amoxicillin (500 mg, three times daily) could be considered.

Fifth, for patients with fever and possible exposure to L monocytogenes, blood cultures should be drawn immediately, and high-dose ampicillin should be initiated, along with electronic fetal heart rate monitoring.

“While choosing safer foods in pregnancy is recommended, it is most important to be aware of Health Canada food recalls and pay attention to symptoms if you’ve ingested these foods,” said Dr. Wong. “Working with the BC Centre for Disease Control, our teams are actively monitoring for cases of listeriosis in pregnancy here in British Columbia.

“Thankfully,” he said, “there haven’t been any confirmed cases in British Columbia related to the plant-based milk recall, though the bacteria’s incubation period can be up to 70 days in pregnancy.”
 

No Increase Suspected

Commenting on the article, Khady Diouf, MD, director of global obstetrics and gynecology at Brigham and Women’s Hospital in Boston, said, “It summarizes the main management, which is based mostly on expert opinion.”

US clinicians also should be reminded about listeriosis in pregnancy, she noted, pointing to “helpful guidance” from the American College of Obstetrics and Gynecology.

Although the United States similarly experienced a recent listeriosis outbreak resulting from contaminated deli meats, both Dr. Wong and Dr. Diouf said that these outbreaks do not seem to signal an increase in listeriosis cases overall.

“Food-borne listeriosis seems to come in waves,” said Dr. Wong. “At a public health level, we certainly have better surveillance programs for Listeria infections. In 2023, Health Canada updated its Policy on L monocytogenes in ready-to-eat foods, which emphasizes the good manufacturing practices recommended for food processing environments to identify outbreaks earlier.”

“I think we get these recalls yearly, and this has been the case for as long as I can remember,” Dr. Diouf agreed.

No funding was declared, and the authors declared no relevant financial relationships.

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

Listeriosis during pregnancy, when invasive, can be fatal for the fetus, with a rate of fetal loss or neonatal death of 29%, investigators reported in an article alerting clinicians to this condition.

The article was prompted when the Reproductive Infectious Diseases team at The University of British Columbia in Vancouver, British Columbia, Canada, “received many phone calls from concerned doctors and patients after the plant-based milk recall in early July,” Jeffrey Man Hay Wong, MD, told this news organization. “With such concerns, we updated our British Columbia guidelines for our patients but quickly realized that our recommendations would be useful across the country.”

The article was published online in the Canadian Medical Association Journal.


 

Five Key Points

Dr. Wong and colleagues provided the following five points and recommendations:

First, invasive listeriosis (bacteremia or meningitis) in pregnancy can have major fetal consequences, including fetal loss or neonatal death in 29% of cases. Affected patients can be asymptomatic or experience gastrointestinal symptoms, myalgias, fevers, acute respiratory distress syndrome, or sepsis.

Second, pregnant people should avoid foods at a high risk for Listeria monocytogenes contamination, including unpasteurized dairy products, luncheon meats, refrigerated meat spreads, and prepared salads. They also should stay aware of Health Canada recalls.

Third, it is not necessary to investigate or treat patients who may have ingested contaminated food but are asymptomatic. Listeriosis can present at 2-3 months after exposure because the incubation period can be as long as 70 days.

Fourth, for patients with mild gastroenteritis or flu-like symptoms who may have ingested contaminated food, obtaining blood cultures or starting a 2-week course of oral amoxicillin (500 mg, three times daily) could be considered.

Fifth, for patients with fever and possible exposure to L monocytogenes, blood cultures should be drawn immediately, and high-dose ampicillin should be initiated, along with electronic fetal heart rate monitoring.

“While choosing safer foods in pregnancy is recommended, it is most important to be aware of Health Canada food recalls and pay attention to symptoms if you’ve ingested these foods,” said Dr. Wong. “Working with the BC Centre for Disease Control, our teams are actively monitoring for cases of listeriosis in pregnancy here in British Columbia.

“Thankfully,” he said, “there haven’t been any confirmed cases in British Columbia related to the plant-based milk recall, though the bacteria’s incubation period can be up to 70 days in pregnancy.”
 

No Increase Suspected

Commenting on the article, Khady Diouf, MD, director of global obstetrics and gynecology at Brigham and Women’s Hospital in Boston, said, “It summarizes the main management, which is based mostly on expert opinion.”

US clinicians also should be reminded about listeriosis in pregnancy, she noted, pointing to “helpful guidance” from the American College of Obstetrics and Gynecology.

Although the United States similarly experienced a recent listeriosis outbreak resulting from contaminated deli meats, both Dr. Wong and Dr. Diouf said that these outbreaks do not seem to signal an increase in listeriosis cases overall.

“Food-borne listeriosis seems to come in waves,” said Dr. Wong. “At a public health level, we certainly have better surveillance programs for Listeria infections. In 2023, Health Canada updated its Policy on L monocytogenes in ready-to-eat foods, which emphasizes the good manufacturing practices recommended for food processing environments to identify outbreaks earlier.”

“I think we get these recalls yearly, and this has been the case for as long as I can remember,” Dr. Diouf agreed.

No funding was declared, and the authors declared no relevant financial relationships.

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

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

The Diagnosis: Mycobacterial Infection

An injury sustained in a wet environment that results in chronic indolent abscesses, nodules, or draining sinus tracts suggests a mycobacterial infection. In our patient, a culture revealed MycobacteriuM fortuitum, which is classified in the rapid grower nontuberculous mycobacteria (NTM) group, along with Mycobacterium chelonae and Mycobacterium abscessus.¹ The patient’s history of skin injury while cutting wet grass and the common presence of M fortuitum in the environment suggested that the organism entered the wound. The patient healed completely following surgical excision and a 2-month course of clarithromycin 1 g daily and rifampin 600 mg daily.

MycobacteriuM fortuitum was first isolated from an amphibian source in 1905 and later identified in a human with cutaneous infection in 1938. It commonly is found in soil and water.2 Skin and soft-tissue infections with M fortuitum usually are acquired from direct entry of the organism through a damaged skin barrier from trauma, medical injection, surgery, or tattoo placement.^2,3

Skin lesions caused by NTM often are nonspecific and can mimic a variety of other dermatologic conditions, making clinical diagnosis challenging. As such, cutaneous manifestations of M fortuitum infection can include recurrent cutaneous abscesses, nodular lesions, chronic discharging sinuses, cellulitis, and surgical site infections.4 Although cutaneous infection with M fortuitum classically manifests with a single subcutaneous nodule at the site of trauma or surgery,⁵ it also can manifest as multiple draining sinus tracts, as seen in our patient. Hence, the diagnosis and treatment of cutaneous NTM infection is challenging, especially when M fortuitum skin manifestations can take up to 4 to 6 weeks to develop after inoculation. Diagnosis often requires a detailed patient history, tissue cultures, and histopathology.⁵

In recent years, rapid detection with polymerase chain reaction (PCR) techniques has been employed more widely. Notably, a molecular system based on multiplex real-time PCR with high-resolution melting was shown to have a sensitivity of up to 54% for distinguishing M fortuitum from other NTM.⁶ More recently, a 2-step real-time PCR method has demonstrated diagnostic sensitivity and specificity for differentiating NTM from Mycobacterium tuberculosis infections and identifying the causative NTM agent.⁷

Compared to immunocompetent individuals, those who are immunocompromised are more susceptible to less pathogenic strains of NTM, which can cause dissemination and lead to tenosynovitis, myositis, osteomyelitis, and septic arthritis.^8-12 Nonetheless, cases of infections with NTM—including M fortuitum—are becoming harder to treat. Several single nucleotide polymorphisms and point mutations have been demonstrated in the ribosomal RNA methylase gene erm(39) related to clarithromycin resistance and in the rrl gene related to linezolid resistance.¹³ Due to increasing inducible resistance to common classes of antibiotics, such as macrolides and linezolid, treatment of M fortuitum requires multidrug regimens.^13,14 Drug susceptibility testing also may be required, as M fortuitum has shown low resistance to tigecycline, tetracycline, cefmetazole, imipenem, and aminoglycosides (eg, amikacin, tobramycin, neomycin, gentamycin). Surgery is an important adjunctive tool in treating M fortuitum infections; patients with a single lesion are more likely to undergo surgical treatment alone or in combination with antibiotic therapy.¹⁵ More recently, antimicrobial photodynamic therapy has been explored as an alternative to eliminate NTM, including M fortuitum.¹⁶

The differential diagnosis for skin lesions manifesting with draining fistulae and sinus tracts includes conditions with infectious (cellulitis and chromomycosis) and inflammatory (pyoderma gangrenosum [PG] and hidradenitis suppurativa [HS]) causes.

Cellulitis is a common infection of the skin and subcutaneous tissue that predominantly is caused by gram-positive organisms such as β-hemolytic streptococci.¹⁷ Clinical manifestations include acute skin erythema, swelling, tenderness, and warmth. The legs are the most common sites of infection, but any area of the skin can be involved.17 Cellulitis comprises 10% of all infectious disease hospitalizations and up to 11% of all dermatologic admissions.^18,19 It frequently is misdiagnosed, perhaps due to the lack of a reliable confirmatory laboratory test or imaging study, in addition to the plethora of diseases that mimic cellulitis, such as stasis dermatitis, lipodermatosclerosis, contact dermatitis, lymphedema, eosinophilic cellulitis, and papular urticaria.^20,21 The consequences of misdiagnosis include but are not limited to unnecessary hospitalizations, inappropriate antibiotic use, and delayed management of the disease; thus, there is an urgent need for a reliable standard test to confirm the diagnosis, especially among nonspecialist physicians. ²⁰ Most patients with uncomplicated cellulitis can be treated with empiric oral antibiotics that target β-hemolytic streptococci (ie, penicillin V potassium, amoxicillin).¹⁷ Methicillin-resistant Staphylococcus aureus coverage generally is unnecessary for nonpurulent cellulitis, but clinicians can consider adding amoxicillin-clavulanate, dicloxacillin, and cephalexin to the regimen. For purulent cellulitis, incision and drainage should be performed. In severe cases that manifest with sepsis, altered mental status, or hemodynamic instability, inpatient management is required.¹⁷

Chromomycosis (also known as chromoblastomycosis) is a chronic, indolent, granulomatous, suppurative mycosis of the skin and subcutaneous tissue²² that is caused by traumatic inoculation of various fungi of the order Chaetothyriales and family Herpotrichiellaceae, which are present in soil, plants, and decomposing wood. Chromomycosis is prevalent in tropical and subtropical regions.^23,24 Clinically, it manifests as oligosymptomatic or asymptomatic lesions around an infection site that can manifest as papules with centrifugal growth evolving into nodular, verrucous, plaque, tumoral, or atrophic forms.²² Diagnosis is made with direct microscopy using potassium hydroxide, which reveals muriform bodies. Fungal culture in Sabouraud agar also can be used to isolate the causative pathogen.²² Unfortunately, chromomycosis is difficult to treat, with low cure rates and high relapse rates. Antifungal agents combined with surgery, cryotherapy, or thermotherapy often are used, with cure rates ranging from 15% to 80%.^22,25

Pyoderma gangrenosum is a reactive noninfectious inflammatory dermatosis associated with inflammatory bowel disease and rheumatoid arthritis. The exact etiology is not clearly understood, but it generally is considered an autoinflammatory disorder.²⁶ The most common form—classical PG—occurs in approximately 85% of cases and manifests as a painful erythematous lesion that progresses to a blistered or necrotic ulcer. It primarily affects the lower legs but can occur in other body sites.²⁷ The diagnosis is based on clinical symptoms after excluding other similar conditions; histopathology of biopsied wound tissues often are required for confirmation. Treatment of PG starts with fast-acting immunosuppressive drugs (corticosteroids and/or cyclosporine) followed by slowacting immunosuppressive drugs (biologics).²⁶

Hidradenitis suppurativa is a chronic recurrent disease of the hair follicle unit that develops after puberty.²⁸ Clinically, HS manifests with painful nodules, abscesses, chronically draining fistulas, and scarring in areas of the body rich in apocrine glands.^29,30 Treatment of HS is challenging due to its diverse clinical manifestations and unclear etiology. Topical therapy, systemic treatments, biologic agents, surgery, and light therapy have shown variable results.^28,31

The Diagnosis: Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is a type 2 reaction sometimes seen in patients infected with Mycobacterium leprae—primarily those with lepromatous or borderline lepromatous subtypes. Clinically, ENL manifests with abrupt onset of tender erythematous papules with associated fevers and general malaise. Studies have demonstrated a complex immune system reaction in ENL, but the detailed pathophysiology is not fully understood.¹ Biopsies conducted within 24 hours of lesion formation are most elucidating. Foamy histiocytes admixed with neutrophils are seen in the subcutis, often causing a lobular panniculitis (quiz image).² Neutrophils rarely are seen in other types of leprosy and thus are a useful diagnostic clue for ENL. Vasculitis of small- to medium-sized vessels can be seen but is not a necessary diagnostic criterion. Fite staining will highlight many acid-fast bacilli within the histiocytes (Figure 1).

Erythema nodosum leprosum is treated with a combination of immunosuppressants such as prednisone and thalidomide. Our patient was taking triple-antibiotic therapy—dapsone, rifampin, and clofazimine—for lepromatous leprosy when the erythematous papules developed on the arms and legs. After a skin biopsy confirmed the diagnosis of ENL, he was started on prednisone 20 mg daily with plans for close follow-up. Unfortunately, the patient was subsequently lost to follow-up.

Acute febrile neutrophilic dermatosis (also known as Sweet syndrome) is an acute inflammatory disease characterized by abrupt onset of painful erythematous papules, plaques, or nodules on the skin. It often is seen in association with preceding infections (especially those in the upper respiratory or gastrointestinal tracts), hematologic malignancies, inflammatory bowel disease, or exposure to certain classes of medications (eg, granulocyte colony-stimulating factor, tyrosine kinase inhibitors, various antibiotics).³ Histologically, acute febrile neutrophilic dermatosis is characterized by dense neutrophilic infiltrates, often with notable dermal edema (Figure 2).⁴ Many cases also show leukocytoclastic vasculitis; however, foamy histiocytes are not a notable component of the inflammatory infiltrate, though a histiocytoid form of acute febrile neutrophilic dermatosis has been described.⁵ Infections must be rigorously ruled out prior to diagnosing a patient with acute febrile neutrophilic dermatosis, making it a diagnosis of exclusion.

Cutaneous coccidioidomycosis is an infection caused by the dimorphic fungi Coccidioides immitis or Coccidioides posadasii. Cutaneous disease is rare but can occur from direct inoculation or dissemination from pulmonary disease in immunocompetent or immunocompromised patients. Papules, pustules, or plaques are seen clinically. Histologically, cutaneous coccidioidomycosis shows spherules that vary from 10 to 100 μm and are filled with multiple smaller endospores (Figure 3).⁶ Pseudoepitheliomatous hyperplasia with dense suppurative and granulomatous infiltrates also is seen.

Erythema induratum is characterized by tender nodules on the lower extremities and has a substantial female predominance. Many cases are associated with Mycobacterium tuberculosis infection. The bacteria are not seen directly in the skin but are instead detectable through DNA polymerase chain reaction testing or investigation of other organ systems.^7,8 Histologically, lesions show a lobular panniculitis with a mixed infiltrate. Vasculitis is seen in approximately 90% of erythema induratum cases vs approximately 25% of classic ENL cases (Figure 4),^2,9 which has led some to use the term nodular vasculitis to describe this disease entity. Nodular vasculitis is considered by others to be a distinct disease entity in which there are clinical and histologic features similar to erythema induratum but no evidence of M tuberculosis infection.⁹

Polyarteritis nodosa is a vasculitis that affects medium- sized vessels of various organ systems. The presenting signs and symptoms vary based on the affected organ systems. Palpable to retiform purpura, livedo racemosa, subcutaneous nodules, or ulcers are seen when the skin is involved. The histologic hallmark is necrotizing vasculitis of medium-sized arterioles (Figure 5), although leukocytoclastic vasculitis of small-caliber vessels also can be seen in biopsies of affected skin.¹⁰ The vascular changes are said to be segmental, with uninvolved segments interspersed with involved segments. Antineutrophil cytoplasmic antibody (ANCA)– associated vasculitis also must be considered when one sees leukocytoclastic vasculitis of small-caliber vessels in the skin, as it can be distinguished most readily by detecting circulating antibodies specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA).

The Diagnosis: Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is a type 2 reaction sometimes seen in patients infected with Mycobacterium leprae—primarily those with lepromatous or borderline lepromatous subtypes. Clinically, ENL manifests with abrupt onset of tender erythematous papules with associated fevers and general malaise. Studies have demonstrated a complex immune system reaction in ENL, but the detailed pathophysiology is not fully understood.¹ Biopsies conducted within 24 hours of lesion formation are most elucidating. Foamy histiocytes admixed with neutrophils are seen in the subcutis, often causing a lobular panniculitis (quiz image).² Neutrophils rarely are seen in other types of leprosy and thus are a useful diagnostic clue for ENL. Vasculitis of small- to medium-sized vessels can be seen but is not a necessary diagnostic criterion. Fite staining will highlight many acid-fast bacilli within the histiocytes (Figure 1).

Erythema nodosum leprosum is treated with a combination of immunosuppressants such as prednisone and thalidomide. Our patient was taking triple-antibiotic therapy—dapsone, rifampin, and clofazimine—for lepromatous leprosy when the erythematous papules developed on the arms and legs. After a skin biopsy confirmed the diagnosis of ENL, he was started on prednisone 20 mg daily with plans for close follow-up. Unfortunately, the patient was subsequently lost to follow-up.

Acute febrile neutrophilic dermatosis (also known as Sweet syndrome) is an acute inflammatory disease characterized by abrupt onset of painful erythematous papules, plaques, or nodules on the skin. It often is seen in association with preceding infections (especially those in the upper respiratory or gastrointestinal tracts), hematologic malignancies, inflammatory bowel disease, or exposure to certain classes of medications (eg, granulocyte colony-stimulating factor, tyrosine kinase inhibitors, various antibiotics).³ Histologically, acute febrile neutrophilic dermatosis is characterized by dense neutrophilic infiltrates, often with notable dermal edema (Figure 2).⁴ Many cases also show leukocytoclastic vasculitis; however, foamy histiocytes are not a notable component of the inflammatory infiltrate, though a histiocytoid form of acute febrile neutrophilic dermatosis has been described.⁵ Infections must be rigorously ruled out prior to diagnosing a patient with acute febrile neutrophilic dermatosis, making it a diagnosis of exclusion.

Cutaneous coccidioidomycosis is an infection caused by the dimorphic fungi Coccidioides immitis or Coccidioides posadasii. Cutaneous disease is rare but can occur from direct inoculation or dissemination from pulmonary disease in immunocompetent or immunocompromised patients. Papules, pustules, or plaques are seen clinically. Histologically, cutaneous coccidioidomycosis shows spherules that vary from 10 to 100 μm and are filled with multiple smaller endospores (Figure 3).⁶ Pseudoepitheliomatous hyperplasia with dense suppurative and granulomatous infiltrates also is seen.

Erythema induratum is characterized by tender nodules on the lower extremities and has a substantial female predominance. Many cases are associated with Mycobacterium tuberculosis infection. The bacteria are not seen directly in the skin but are instead detectable through DNA polymerase chain reaction testing or investigation of other organ systems.^7,8 Histologically, lesions show a lobular panniculitis with a mixed infiltrate. Vasculitis is seen in approximately 90% of erythema induratum cases vs approximately 25% of classic ENL cases (Figure 4),^2,9 which has led some to use the term nodular vasculitis to describe this disease entity. Nodular vasculitis is considered by others to be a distinct disease entity in which there are clinical and histologic features similar to erythema induratum but no evidence of M tuberculosis infection.⁹

Polyarteritis nodosa is a vasculitis that affects medium- sized vessels of various organ systems. The presenting signs and symptoms vary based on the affected organ systems. Palpable to retiform purpura, livedo racemosa, subcutaneous nodules, or ulcers are seen when the skin is involved. The histologic hallmark is necrotizing vasculitis of medium-sized arterioles (Figure 5), although leukocytoclastic vasculitis of small-caliber vessels also can be seen in biopsies of affected skin.¹⁰ The vascular changes are said to be segmental, with uninvolved segments interspersed with involved segments. Antineutrophil cytoplasmic antibody (ANCA)– associated vasculitis also must be considered when one sees leukocytoclastic vasculitis of small-caliber vessels in the skin, as it can be distinguished most readily by detecting circulating antibodies specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA).

The Diagnosis: Erythema Nodosum Leprosum

Erythema nodosum leprosum (ENL) is a type 2 reaction sometimes seen in patients infected with Mycobacterium leprae—primarily those with lepromatous or borderline lepromatous subtypes. Clinically, ENL manifests with abrupt onset of tender erythematous papules with associated fevers and general malaise. Studies have demonstrated a complex immune system reaction in ENL, but the detailed pathophysiology is not fully understood.¹ Biopsies conducted within 24 hours of lesion formation are most elucidating. Foamy histiocytes admixed with neutrophils are seen in the subcutis, often causing a lobular panniculitis (quiz image).² Neutrophils rarely are seen in other types of leprosy and thus are a useful diagnostic clue for ENL. Vasculitis of small- to medium-sized vessels can be seen but is not a necessary diagnostic criterion. Fite staining will highlight many acid-fast bacilli within the histiocytes (Figure 1).

Erythema nodosum leprosum is treated with a combination of immunosuppressants such as prednisone and thalidomide. Our patient was taking triple-antibiotic therapy—dapsone, rifampin, and clofazimine—for lepromatous leprosy when the erythematous papules developed on the arms and legs. After a skin biopsy confirmed the diagnosis of ENL, he was started on prednisone 20 mg daily with plans for close follow-up. Unfortunately, the patient was subsequently lost to follow-up.

Acute febrile neutrophilic dermatosis (also known as Sweet syndrome) is an acute inflammatory disease characterized by abrupt onset of painful erythematous papules, plaques, or nodules on the skin. It often is seen in association with preceding infections (especially those in the upper respiratory or gastrointestinal tracts), hematologic malignancies, inflammatory bowel disease, or exposure to certain classes of medications (eg, granulocyte colony-stimulating factor, tyrosine kinase inhibitors, various antibiotics).³ Histologically, acute febrile neutrophilic dermatosis is characterized by dense neutrophilic infiltrates, often with notable dermal edema (Figure 2).⁴ Many cases also show leukocytoclastic vasculitis; however, foamy histiocytes are not a notable component of the inflammatory infiltrate, though a histiocytoid form of acute febrile neutrophilic dermatosis has been described.⁵ Infections must be rigorously ruled out prior to diagnosing a patient with acute febrile neutrophilic dermatosis, making it a diagnosis of exclusion.

Cutaneous coccidioidomycosis is an infection caused by the dimorphic fungi Coccidioides immitis or Coccidioides posadasii. Cutaneous disease is rare but can occur from direct inoculation or dissemination from pulmonary disease in immunocompetent or immunocompromised patients. Papules, pustules, or plaques are seen clinically. Histologically, cutaneous coccidioidomycosis shows spherules that vary from 10 to 100 μm and are filled with multiple smaller endospores (Figure 3).⁶ Pseudoepitheliomatous hyperplasia with dense suppurative and granulomatous infiltrates also is seen.

Erythema induratum is characterized by tender nodules on the lower extremities and has a substantial female predominance. Many cases are associated with Mycobacterium tuberculosis infection. The bacteria are not seen directly in the skin but are instead detectable through DNA polymerase chain reaction testing or investigation of other organ systems.^7,8 Histologically, lesions show a lobular panniculitis with a mixed infiltrate. Vasculitis is seen in approximately 90% of erythema induratum cases vs approximately 25% of classic ENL cases (Figure 4),^2,9 which has led some to use the term nodular vasculitis to describe this disease entity. Nodular vasculitis is considered by others to be a distinct disease entity in which there are clinical and histologic features similar to erythema induratum but no evidence of M tuberculosis infection.⁹

Polyarteritis nodosa is a vasculitis that affects medium- sized vessels of various organ systems. The presenting signs and symptoms vary based on the affected organ systems. Palpable to retiform purpura, livedo racemosa, subcutaneous nodules, or ulcers are seen when the skin is involved. The histologic hallmark is necrotizing vasculitis of medium-sized arterioles (Figure 5), although leukocytoclastic vasculitis of small-caliber vessels also can be seen in biopsies of affected skin.¹⁰ The vascular changes are said to be segmental, with uninvolved segments interspersed with involved segments. Antineutrophil cytoplasmic antibody (ANCA)– associated vasculitis also must be considered when one sees leukocytoclastic vasculitis of small-caliber vessels in the skin, as it can be distinguished most readily by detecting circulating antibodies specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA).

This transcript has been edited for clarity.

In my job, I spend 99% of my time thinking about ethical issues that arise in the care of human beings. That is the focus of our medical school, and that’s what we do. 

However, there are behaviors that are emerging with respect to pets that bear on human health and require the attention of doctors and nurses who deal with people who are pet owners.

Recently, there has been a great increase in the number of pet owners who are saying, “I’m not going to vaccinate my pets.” As horrible as this sounds, what’s happening is vaccine hesitancy about vaccines used in humans is extending through some people to their pets. 

The number of people who say they don’t trust things like rabies vaccine to be effective or safe for their pet animals is 40%, at least in surveys, and the American Veterinary Medical Association reports that 15%-18% of pet owners are not, in fact, vaccinating their pets against rabies.

Rabies, as I hope everybody knows, is one horrible disease. Even the treatment of it, should you get bitten by a rabid animal, is no fun, expensive, and hopefully something that can be administered quickly. It’s not always the case. Worldwide, at least 70,000 people die from rabies every year.

Obviously, there are many countries that are so terrified of rabies, they won’t let you bring pets in without quarantining them, say, England, for at least 6 months to a year, I believe, because they don’t want rabies getting into their country. They’re very strict about the movement of pets.

It is inexcusable for people, first, not to give their pets vaccines that prevent them getting distemper, parvovirus, or many other diseases that harm the pet. It’s also inexcusable to shorten your pet’s life or ask your patients to care for pets who get sick from many of these diseases that are vaccine preventable.

Worst of all, it’s inexcusable for any pet owner not to give a rabies vaccine to their pets. Were it up to me, I’d say you have to license your pet, and as part of that, you must mandate rabies vaccines for your dogs, cats, and other pets. 

We know what happens when people encounter wild animals like raccoons and rabbits. It is not a good situation. Your pets can easily encounter a rabid animal and then put themselves in a position where they can harm their human owners. 

We have an efficacious, safe treatment. If you’re dealing with someone, it might make sense to ask them, “Do you own a pet? Are you vaccinating?” It may not be something you’d ever thought about, but what we don’t need is rabies back in a bigger way in the United States than it’s been in the past.

I think, as a matter of prudence and public health, maybe firing up that question, “Got a pet in the house and are you vaccinating,” could be part of taking a good history.

 

Dr. Caplan is director of the division of medical ethics at New York University Langone Medical Center, New York City. He disclosed conflicts of interest with Johnson & Johnson and Medscape.

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

This transcript has been edited for clarity.

In my job, I spend 99% of my time thinking about ethical issues that arise in the care of human beings. That is the focus of our medical school, and that’s what we do. 

However, there are behaviors that are emerging with respect to pets that bear on human health and require the attention of doctors and nurses who deal with people who are pet owners.

Recently, there has been a great increase in the number of pet owners who are saying, “I’m not going to vaccinate my pets.” As horrible as this sounds, what’s happening is vaccine hesitancy about vaccines used in humans is extending through some people to their pets. 

The number of people who say they don’t trust things like rabies vaccine to be effective or safe for their pet animals is 40%, at least in surveys, and the American Veterinary Medical Association reports that 15%-18% of pet owners are not, in fact, vaccinating their pets against rabies.

Rabies, as I hope everybody knows, is one horrible disease. Even the treatment of it, should you get bitten by a rabid animal, is no fun, expensive, and hopefully something that can be administered quickly. It’s not always the case. Worldwide, at least 70,000 people die from rabies every year.

Obviously, there are many countries that are so terrified of rabies, they won’t let you bring pets in without quarantining them, say, England, for at least 6 months to a year, I believe, because they don’t want rabies getting into their country. They’re very strict about the movement of pets.

It is inexcusable for people, first, not to give their pets vaccines that prevent them getting distemper, parvovirus, or many other diseases that harm the pet. It’s also inexcusable to shorten your pet’s life or ask your patients to care for pets who get sick from many of these diseases that are vaccine preventable.

Worst of all, it’s inexcusable for any pet owner not to give a rabies vaccine to their pets. Were it up to me, I’d say you have to license your pet, and as part of that, you must mandate rabies vaccines for your dogs, cats, and other pets. 

We know what happens when people encounter wild animals like raccoons and rabbits. It is not a good situation. Your pets can easily encounter a rabid animal and then put themselves in a position where they can harm their human owners. 

We have an efficacious, safe treatment. If you’re dealing with someone, it might make sense to ask them, “Do you own a pet? Are you vaccinating?” It may not be something you’d ever thought about, but what we don’t need is rabies back in a bigger way in the United States than it’s been in the past.

I think, as a matter of prudence and public health, maybe firing up that question, “Got a pet in the house and are you vaccinating,” could be part of taking a good history.

 

Dr. Caplan is director of the division of medical ethics at New York University Langone Medical Center, New York City. He disclosed conflicts of interest with Johnson & Johnson and Medscape.

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

This transcript has been edited for clarity.

In my job, I spend 99% of my time thinking about ethical issues that arise in the care of human beings. That is the focus of our medical school, and that’s what we do. 

However, there are behaviors that are emerging with respect to pets that bear on human health and require the attention of doctors and nurses who deal with people who are pet owners.

Recently, there has been a great increase in the number of pet owners who are saying, “I’m not going to vaccinate my pets.” As horrible as this sounds, what’s happening is vaccine hesitancy about vaccines used in humans is extending through some people to their pets. 

The number of people who say they don’t trust things like rabies vaccine to be effective or safe for their pet animals is 40%, at least in surveys, and the American Veterinary Medical Association reports that 15%-18% of pet owners are not, in fact, vaccinating their pets against rabies.

Rabies, as I hope everybody knows, is one horrible disease. Even the treatment of it, should you get bitten by a rabid animal, is no fun, expensive, and hopefully something that can be administered quickly. It’s not always the case. Worldwide, at least 70,000 people die from rabies every year.

Obviously, there are many countries that are so terrified of rabies, they won’t let you bring pets in without quarantining them, say, England, for at least 6 months to a year, I believe, because they don’t want rabies getting into their country. They’re very strict about the movement of pets.

It is inexcusable for people, first, not to give their pets vaccines that prevent them getting distemper, parvovirus, or many other diseases that harm the pet. It’s also inexcusable to shorten your pet’s life or ask your patients to care for pets who get sick from many of these diseases that are vaccine preventable.

Worst of all, it’s inexcusable for any pet owner not to give a rabies vaccine to their pets. Were it up to me, I’d say you have to license your pet, and as part of that, you must mandate rabies vaccines for your dogs, cats, and other pets. 

We know what happens when people encounter wild animals like raccoons and rabbits. It is not a good situation. Your pets can easily encounter a rabid animal and then put themselves in a position where they can harm their human owners. 

We have an efficacious, safe treatment. If you’re dealing with someone, it might make sense to ask them, “Do you own a pet? Are you vaccinating?” It may not be something you’d ever thought about, but what we don’t need is rabies back in a bigger way in the United States than it’s been in the past.

I think, as a matter of prudence and public health, maybe firing up that question, “Got a pet in the house and are you vaccinating,” could be part of taking a good history.

 

Dr. Caplan is director of the division of medical ethics at New York University Langone Medical Center, New York City. He disclosed conflicts of interest with Johnson & Johnson and Medscape.

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

TOPLINE:

The prevalence of recurrent urinary tract infections (rUTIs) and the use of antibiotics for prevention are substantial among women in Wales, particularly among those over the age of 57 years. A high level of resistance to two recommended antibiotics was observed, suggesting that more frequent urine cultures could better guide antibiotic selection for treatment and prophylaxis.

METHODOLOGY:

• The researchers conducted a retrospective cross-sectional study using a large databank of patients in Wales to describe the characteristics and urine profiles of women with rUTIs between 2010 and 2022.
• They created two cohorts: One with 92,213 women (median age, 60 years) who experienced rUTIs, defined as two or more acute episodes within 6 months or three or more acute episodes within 12 months.
• Another cohort comprised of 26,862 women (median age, 71 years) were prescribed prophylactic antibiotics, which was defined as receiving three or more consecutive prescriptions of the same UTI-specific antibiotic (trimethoprim, nitrofurantoin, or cefalexin), with intervals of 21-56 days between prescriptions.
• Urine culture results in the 12 months before a rUTI diagnosis and 18 months before prophylactic antibiotic initiation and all urine culture results within 7 days of an acute UTI were analyzed to assess antibiotic resistance patterns.

TAKEAWAY:

• Overall, 6% of women had rUTIs, 1.7% of which were prescribed prophylactic antibiotics with proportions increasing sharply after age 57.
• Nearly half of the women (49%) who were prescribed a prophylactic antibiotic qualified as having rUTIs in the 18 months before initiation.
• This study showed that 80.8% of women with rUTIs had a urine culture result documented in the 12 months preceding the diagnosis.
• More than half (64%) of the women taking prophylactic antibiotics had a urine culture result documented before starting treatment, and 18% of those prescribed trimethoprim had resistance to the antibiotic.

IN PRACTICE:

“More frequent urine cultures in the workup of rUTI diagnosis and prophylactic antibiotic initiation could better inform antibiotic choice,” the authors wrote.

SOURCE:

The study was led by Leigh Sanyaolu, BSc (Hons), MRCS, MRCGP, PGDip, a general practitioner from the Division of Population Medicine and PRIME Centre Wales at Cardiff University in Cardiff, and was published online in the British Journal of General Practice.

LIMITATIONS:

The study’s reliance on electronic health records may have led to coding errors and missing data. The diagnosis of UTIs may have been difficult in older women with increased frailty as they can have fewer specific symptoms and asymptomatic bacteriuria, which can be misdiagnosed as a UTI.

DISCLOSURES:

This work was supported by Health and Care Research Wales. The authors declared no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.

TOPLINE:

The prevalence of recurrent urinary tract infections (rUTIs) and the use of antibiotics for prevention are substantial among women in Wales, particularly among those over the age of 57 years. A high level of resistance to two recommended antibiotics was observed, suggesting that more frequent urine cultures could better guide antibiotic selection for treatment and prophylaxis.

METHODOLOGY:

• The researchers conducted a retrospective cross-sectional study using a large databank of patients in Wales to describe the characteristics and urine profiles of women with rUTIs between 2010 and 2022.
• They created two cohorts: One with 92,213 women (median age, 60 years) who experienced rUTIs, defined as two or more acute episodes within 6 months or three or more acute episodes within 12 months.
• Another cohort comprised of 26,862 women (median age, 71 years) were prescribed prophylactic antibiotics, which was defined as receiving three or more consecutive prescriptions of the same UTI-specific antibiotic (trimethoprim, nitrofurantoin, or cefalexin), with intervals of 21-56 days between prescriptions.
• Urine culture results in the 12 months before a rUTI diagnosis and 18 months before prophylactic antibiotic initiation and all urine culture results within 7 days of an acute UTI were analyzed to assess antibiotic resistance patterns.

TAKEAWAY:

• Overall, 6% of women had rUTIs, 1.7% of which were prescribed prophylactic antibiotics with proportions increasing sharply after age 57.
• Nearly half of the women (49%) who were prescribed a prophylactic antibiotic qualified as having rUTIs in the 18 months before initiation.
• This study showed that 80.8% of women with rUTIs had a urine culture result documented in the 12 months preceding the diagnosis.
• More than half (64%) of the women taking prophylactic antibiotics had a urine culture result documented before starting treatment, and 18% of those prescribed trimethoprim had resistance to the antibiotic.

IN PRACTICE:

“More frequent urine cultures in the workup of rUTI diagnosis and prophylactic antibiotic initiation could better inform antibiotic choice,” the authors wrote.

SOURCE:

The study was led by Leigh Sanyaolu, BSc (Hons), MRCS, MRCGP, PGDip, a general practitioner from the Division of Population Medicine and PRIME Centre Wales at Cardiff University in Cardiff, and was published online in the British Journal of General Practice.

LIMITATIONS:

The study’s reliance on electronic health records may have led to coding errors and missing data. The diagnosis of UTIs may have been difficult in older women with increased frailty as they can have fewer specific symptoms and asymptomatic bacteriuria, which can be misdiagnosed as a UTI.

DISCLOSURES:

This work was supported by Health and Care Research Wales. The authors declared no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.

TOPLINE:

The prevalence of recurrent urinary tract infections (rUTIs) and the use of antibiotics for prevention are substantial among women in Wales, particularly among those over the age of 57 years. A high level of resistance to two recommended antibiotics was observed, suggesting that more frequent urine cultures could better guide antibiotic selection for treatment and prophylaxis.

METHODOLOGY:

• The researchers conducted a retrospective cross-sectional study using a large databank of patients in Wales to describe the characteristics and urine profiles of women with rUTIs between 2010 and 2022.
• They created two cohorts: One with 92,213 women (median age, 60 years) who experienced rUTIs, defined as two or more acute episodes within 6 months or three or more acute episodes within 12 months.
• Another cohort comprised of 26,862 women (median age, 71 years) were prescribed prophylactic antibiotics, which was defined as receiving three or more consecutive prescriptions of the same UTI-specific antibiotic (trimethoprim, nitrofurantoin, or cefalexin), with intervals of 21-56 days between prescriptions.
• Urine culture results in the 12 months before a rUTI diagnosis and 18 months before prophylactic antibiotic initiation and all urine culture results within 7 days of an acute UTI were analyzed to assess antibiotic resistance patterns.

TAKEAWAY:

• Overall, 6% of women had rUTIs, 1.7% of which were prescribed prophylactic antibiotics with proportions increasing sharply after age 57.
• Nearly half of the women (49%) who were prescribed a prophylactic antibiotic qualified as having rUTIs in the 18 months before initiation.
• This study showed that 80.8% of women with rUTIs had a urine culture result documented in the 12 months preceding the diagnosis.
• More than half (64%) of the women taking prophylactic antibiotics had a urine culture result documented before starting treatment, and 18% of those prescribed trimethoprim had resistance to the antibiotic.

IN PRACTICE:

“More frequent urine cultures in the workup of rUTI diagnosis and prophylactic antibiotic initiation could better inform antibiotic choice,” the authors wrote.

SOURCE:

The study was led by Leigh Sanyaolu, BSc (Hons), MRCS, MRCGP, PGDip, a general practitioner from the Division of Population Medicine and PRIME Centre Wales at Cardiff University in Cardiff, and was published online in the British Journal of General Practice.

LIMITATIONS:

The study’s reliance on electronic health records may have led to coding errors and missing data. The diagnosis of UTIs may have been difficult in older women with increased frailty as they can have fewer specific symptoms and asymptomatic bacteriuria, which can be misdiagnosed as a UTI.

DISCLOSURES:

This work was supported by Health and Care Research Wales. The authors declared no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article first appeared on Medscape.com.