User login
Diagnosing pulmonary tuberculosis in the hospital
An uncommon but serious problem in certain populations
Case
A 40-year-old Indian immigrant presented to the emergency department with hemoptysis. He had had an intermittent productive cough for the past 4 weeks with increasing fatigue and lack of appetite. He also had intermittent fever with drenching night sweats. Chest radiograph and CT scan showed a left upper lobe cavitary lesion with infiltrate. He was admitted to the hospital with concern for pneumonia and to rule out possible active pulmonary tuberculosis.
Background
Active pulmonary tuberculosis (APTB) remains an important but often missed diagnosis in hospitalized patients in the Western world.1,2 Because of its relative rarity, the diagnosis of APTB often is delayed in the United States, which can lead hospitalized patients to nosocomial transmission, unnecessary exposures, patient harm,3 and potentially avoidable cost to the health care system.4 The diagnosis and management can be challenging involving isolation needs, sputum clearance, treatment strategy, and criteria for discharge to home.
Diagnosis
Any patient with risk factors presenting with signs and/or symptoms of APTB such as productive cough for more than 4 weeks, night sweats, weight loss, low-grade fevers, upper lobe cavitary lesions, or hemoptysis should be suspected. The diagnostic work-up for APTB should always begin with a thorough medical and social history. A chest radiograph or a CT scan should always be obtained. Risk factors for infection and for progression to active pulmonary TB are listed below.
Risk factors for TB infection:
- Close contacts of a person with APTB.
- Health care workers.
- Immigrants from high-burden countries.
- Homeless people.
- Individuals who have been incarcerated.
- International travelers.
- HIV patients.
- Intravenous drug users.
Risk factors for progression to APTB:
- HIV infection.
- Intravenous drug use.
- Silicosis.
- Younger than 5 years of age.
- Immunosuppressed.
All patients with suspected or confirmed APTB who cannot be safely discharged home (see discharge considerations below) should be kept in negative-pressure airborne isolation rooms. Isolation can be discontinued once APTB has been ruled out or the patient is determined to be noninfectious based on three consecutive negative sputum smears.
Although rapid and inexpensive, acid-fast bacilli (AFB) smear microscopy has poor sensitivity (45%-80%, with culture-confirmed APTB cases) and poor positive predictive value (50%-80%) for TB in settings in which nontuberculous mycobacteria are commonly isolated. This makes an AFB smear nondiagnostic in the early diagnosis of APTB. The burden of mycobacteria seen in the sputum smear correlates with infectivity.
To improve sensitivity of testing, it is strongly recommended that three AFB smears be completed in 8- to 24-hour intervals and positive smears be accompanied by nucleic acid amplification (NAA) testing.5 If APTB is suspected, but the patient is unable to expectorate, induced sputum samples should be obtained, and, if unable to induce sputum samples, flexible bronchoscopy sampling should be pursued especially for the high-risk populations described above.
The Centers for Disease Control and Prevention recommends that at least one sputum specimen be tested with NAA to expedite the time to diagnosis of APTB. A negative NAA does NOT rule out TB. The turnaround time for this test is about 24-48 hours. NAA has better positive predictive value (greater than 95%) with AFB smear-positive specimens in settings in which nontuberculous mycobacteria are common. The ability to confirm rapidly the presence of Mycobacterium tuberculosis is 50%-80% in AFB smear-negative, culture-positive specimens.6
In patients with clinical or radiologic suspicion of APTB who are unable to produce sputum or have negative sputum smear microscopy results, bronchoscopy is a safe and reliable method for the diagnosis of pulmonary tuberculosis. For the diagnosis of tuberculosis, bronchoalveolar lavage has a sensitivity and specificity of 60% and 100%, respectively. Adding transbronchial biopsy further increases the sensitivity to 84%, and post-bronchoscopy sputum smear microscopy increases the sensitivity to 94%.6
In 2005, the CDC released guidelines for using interferon-gamma release assays (IGRA) to test for M. tuberculosis infection.7 Both tuberculin skin testing (TST) and IGRAs assess lymphocytes’ response to M. tuberculosis. Although these tests can be supportive of a previous tuberculosis infection, they are not diagnostic tests for APTB. Neither an IGRA nor a TST can distinguish latent from active tuberculosis.
Sputum AFB culture remains the preferred method for laboratory confirmation of APTB. Once APTB is confirmed, it is essential for susceptibility testing and genotyping. However, in the absence of a positive culture, APTB can be diagnosed based on signs and symptoms alone in a high-risk patient.
Treatment
A multidisciplinary, patient-centered approach involving the patient, providers, and public health officials is required to accomplish the following treatment goals: eradicating Mycobacterium infection, eliminating the risk of transmission, avoiding the disease, and preventing drug resistance.8
Infectious disease consultation is mandatory in all HIV-positive and suspected or confirmed multidrug-resistant cases. Directly observed therapy is an essential component of APTB treatment to ensure compliance in many situations.
Admission and discharge
Admission to a hospital is not required unless a patient meets criteria for admission independent of APTB diagnosis, or proper risk stratification and assessment cannot be completed in a timely manner. A patient with suspected APTB should be placed in airborne isolation. All staff should wear N95 disposable masks or respirators while inside the patient’s room.9
Discharge considerations are listed below:
- Inform the department of health (DOH).
- Establish proper isolation precautions to minimize exposure.
- Ensure ability to stay at home until DOH and physician determines noninfectivity.
- Educate the patient about length of therapy, directly observed therapy, side effects and importance of compliance.
- Coordinate discharge with the DOH.
- Make sure proper follow-up is scheduled.
Back to the case
Our patient was placed on airborne respiratory isolation immediately upon admission and sputum was sent for AFB. Sputum smear was positive for AFB as well as a positive nucleic acid testing for Mycobacterium tuberculosis. HIV antibody testing was negative. Once the sputum AFB was determined to be positive, the department of health was informed. He was started on the intensive phase of therapy with pyrazinamide, rifampin, ethambutol, and isoniazid along with pyridoxine. He tolerated his medications well and had no immediate reactions. His family and close contacts were screened and advised to be tested.
The patient was discharged after proper follow-up with primary care doctor was scheduled. The department of health arranged for directly observed therapy. He received information about the importance of taking all of his medications and staying at home except for medical visits until the DOH had deemed him to be noninfectious.
Bottom line
APTB in the hospital is an uncommon but serious problem in certain populations. It requires a high index of suspicion and a multidisciplinary approach for effective treatment and prevention of transmission.
Dr. Mallampalli is an attending physician in hospital medicine at Geisinger in Danville, Pa., and clinical assistant professor at Temple University, Philadelphia. Dr. Velidi is an attending physician in hospital medicine at Geisinger. Dr. Courtney is associate director of the department of hospital medicine at Geisinger.
References
1. Miller AC et al. Missed opportunities to diagnose tuberculosis are common among hospitalized patients and patients seen in emergency departments. Open Forum Infectious Diseases. 2015. doi. org/10.1093/ofid/ofv171.
2. Greenaway C et al and the Canadian Collaborative Group in Nosocomial Transmission of Tuberculosis. Delay in diagnosis among hospitalized patients with active tuberculosis–predictors and outcomes. Am J Respir Crit Care Med. 2002 Apr;165:927-33.
3. Medrano BA et al. A missed tuberculosis diagnosis resulting in hospital transmission. Infect Control Hosp Epidemiol. 2014 May;35(5):534-7.
4. Kelly AM et al. Delayed tuberculosis diagnosis and costs of contact investigations for hospital exposure: New York City, 2010-2014. Am J Infect Control. 2017 May 1;45(5):483-6.
5. Lewinsohn DM et al. Official ATS/IDSA/CDC Clinical Practice Guidelines: Diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan;64:111-5.
6. Mazurek GH et al. Guidelines for using the QuantiFERON-TB Gold test for detecting Mycobacterium tuberculosis infection, United States. MMWR Recomm Rep. 2005 Dec 16;54(RR-15):49-55.
7. CDC. Trends in tuberculosis – United States, 2010. MMWR Morb Mortal Wkly Rep. 2011 Mar 25;60(11):333-7.
8. Jensen PA et al. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep. 2005 Dec 30;54(RR-17):1-141.
9. Siegel JD et al and the Health Care Infection Control Practices Advisory Committee. 2007 Guideline for isolation precautions: Preventing transmission of infectious agents in health care settings. Am J Infect Control. 2007 Dec;35(10 Suppl 2):S65-164.
An uncommon but serious problem in certain populations
An uncommon but serious problem in certain populations
Case
A 40-year-old Indian immigrant presented to the emergency department with hemoptysis. He had had an intermittent productive cough for the past 4 weeks with increasing fatigue and lack of appetite. He also had intermittent fever with drenching night sweats. Chest radiograph and CT scan showed a left upper lobe cavitary lesion with infiltrate. He was admitted to the hospital with concern for pneumonia and to rule out possible active pulmonary tuberculosis.
Background
Active pulmonary tuberculosis (APTB) remains an important but often missed diagnosis in hospitalized patients in the Western world.1,2 Because of its relative rarity, the diagnosis of APTB often is delayed in the United States, which can lead hospitalized patients to nosocomial transmission, unnecessary exposures, patient harm,3 and potentially avoidable cost to the health care system.4 The diagnosis and management can be challenging involving isolation needs, sputum clearance, treatment strategy, and criteria for discharge to home.
Diagnosis
Any patient with risk factors presenting with signs and/or symptoms of APTB such as productive cough for more than 4 weeks, night sweats, weight loss, low-grade fevers, upper lobe cavitary lesions, or hemoptysis should be suspected. The diagnostic work-up for APTB should always begin with a thorough medical and social history. A chest radiograph or a CT scan should always be obtained. Risk factors for infection and for progression to active pulmonary TB are listed below.
Risk factors for TB infection:
- Close contacts of a person with APTB.
- Health care workers.
- Immigrants from high-burden countries.
- Homeless people.
- Individuals who have been incarcerated.
- International travelers.
- HIV patients.
- Intravenous drug users.
Risk factors for progression to APTB:
- HIV infection.
- Intravenous drug use.
- Silicosis.
- Younger than 5 years of age.
- Immunosuppressed.
All patients with suspected or confirmed APTB who cannot be safely discharged home (see discharge considerations below) should be kept in negative-pressure airborne isolation rooms. Isolation can be discontinued once APTB has been ruled out or the patient is determined to be noninfectious based on three consecutive negative sputum smears.
Although rapid and inexpensive, acid-fast bacilli (AFB) smear microscopy has poor sensitivity (45%-80%, with culture-confirmed APTB cases) and poor positive predictive value (50%-80%) for TB in settings in which nontuberculous mycobacteria are commonly isolated. This makes an AFB smear nondiagnostic in the early diagnosis of APTB. The burden of mycobacteria seen in the sputum smear correlates with infectivity.
To improve sensitivity of testing, it is strongly recommended that three AFB smears be completed in 8- to 24-hour intervals and positive smears be accompanied by nucleic acid amplification (NAA) testing.5 If APTB is suspected, but the patient is unable to expectorate, induced sputum samples should be obtained, and, if unable to induce sputum samples, flexible bronchoscopy sampling should be pursued especially for the high-risk populations described above.
The Centers for Disease Control and Prevention recommends that at least one sputum specimen be tested with NAA to expedite the time to diagnosis of APTB. A negative NAA does NOT rule out TB. The turnaround time for this test is about 24-48 hours. NAA has better positive predictive value (greater than 95%) with AFB smear-positive specimens in settings in which nontuberculous mycobacteria are common. The ability to confirm rapidly the presence of Mycobacterium tuberculosis is 50%-80% in AFB smear-negative, culture-positive specimens.6
In patients with clinical or radiologic suspicion of APTB who are unable to produce sputum or have negative sputum smear microscopy results, bronchoscopy is a safe and reliable method for the diagnosis of pulmonary tuberculosis. For the diagnosis of tuberculosis, bronchoalveolar lavage has a sensitivity and specificity of 60% and 100%, respectively. Adding transbronchial biopsy further increases the sensitivity to 84%, and post-bronchoscopy sputum smear microscopy increases the sensitivity to 94%.6
In 2005, the CDC released guidelines for using interferon-gamma release assays (IGRA) to test for M. tuberculosis infection.7 Both tuberculin skin testing (TST) and IGRAs assess lymphocytes’ response to M. tuberculosis. Although these tests can be supportive of a previous tuberculosis infection, they are not diagnostic tests for APTB. Neither an IGRA nor a TST can distinguish latent from active tuberculosis.
Sputum AFB culture remains the preferred method for laboratory confirmation of APTB. Once APTB is confirmed, it is essential for susceptibility testing and genotyping. However, in the absence of a positive culture, APTB can be diagnosed based on signs and symptoms alone in a high-risk patient.
Treatment
A multidisciplinary, patient-centered approach involving the patient, providers, and public health officials is required to accomplish the following treatment goals: eradicating Mycobacterium infection, eliminating the risk of transmission, avoiding the disease, and preventing drug resistance.8
Infectious disease consultation is mandatory in all HIV-positive and suspected or confirmed multidrug-resistant cases. Directly observed therapy is an essential component of APTB treatment to ensure compliance in many situations.
Admission and discharge
Admission to a hospital is not required unless a patient meets criteria for admission independent of APTB diagnosis, or proper risk stratification and assessment cannot be completed in a timely manner. A patient with suspected APTB should be placed in airborne isolation. All staff should wear N95 disposable masks or respirators while inside the patient’s room.9
Discharge considerations are listed below:
- Inform the department of health (DOH).
- Establish proper isolation precautions to minimize exposure.
- Ensure ability to stay at home until DOH and physician determines noninfectivity.
- Educate the patient about length of therapy, directly observed therapy, side effects and importance of compliance.
- Coordinate discharge with the DOH.
- Make sure proper follow-up is scheduled.
Back to the case
Our patient was placed on airborne respiratory isolation immediately upon admission and sputum was sent for AFB. Sputum smear was positive for AFB as well as a positive nucleic acid testing for Mycobacterium tuberculosis. HIV antibody testing was negative. Once the sputum AFB was determined to be positive, the department of health was informed. He was started on the intensive phase of therapy with pyrazinamide, rifampin, ethambutol, and isoniazid along with pyridoxine. He tolerated his medications well and had no immediate reactions. His family and close contacts were screened and advised to be tested.
The patient was discharged after proper follow-up with primary care doctor was scheduled. The department of health arranged for directly observed therapy. He received information about the importance of taking all of his medications and staying at home except for medical visits until the DOH had deemed him to be noninfectious.
Bottom line
APTB in the hospital is an uncommon but serious problem in certain populations. It requires a high index of suspicion and a multidisciplinary approach for effective treatment and prevention of transmission.
Dr. Mallampalli is an attending physician in hospital medicine at Geisinger in Danville, Pa., and clinical assistant professor at Temple University, Philadelphia. Dr. Velidi is an attending physician in hospital medicine at Geisinger. Dr. Courtney is associate director of the department of hospital medicine at Geisinger.
References
1. Miller AC et al. Missed opportunities to diagnose tuberculosis are common among hospitalized patients and patients seen in emergency departments. Open Forum Infectious Diseases. 2015. doi. org/10.1093/ofid/ofv171.
2. Greenaway C et al and the Canadian Collaborative Group in Nosocomial Transmission of Tuberculosis. Delay in diagnosis among hospitalized patients with active tuberculosis–predictors and outcomes. Am J Respir Crit Care Med. 2002 Apr;165:927-33.
3. Medrano BA et al. A missed tuberculosis diagnosis resulting in hospital transmission. Infect Control Hosp Epidemiol. 2014 May;35(5):534-7.
4. Kelly AM et al. Delayed tuberculosis diagnosis and costs of contact investigations for hospital exposure: New York City, 2010-2014. Am J Infect Control. 2017 May 1;45(5):483-6.
5. Lewinsohn DM et al. Official ATS/IDSA/CDC Clinical Practice Guidelines: Diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan;64:111-5.
6. Mazurek GH et al. Guidelines for using the QuantiFERON-TB Gold test for detecting Mycobacterium tuberculosis infection, United States. MMWR Recomm Rep. 2005 Dec 16;54(RR-15):49-55.
7. CDC. Trends in tuberculosis – United States, 2010. MMWR Morb Mortal Wkly Rep. 2011 Mar 25;60(11):333-7.
8. Jensen PA et al. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep. 2005 Dec 30;54(RR-17):1-141.
9. Siegel JD et al and the Health Care Infection Control Practices Advisory Committee. 2007 Guideline for isolation precautions: Preventing transmission of infectious agents in health care settings. Am J Infect Control. 2007 Dec;35(10 Suppl 2):S65-164.
Case
A 40-year-old Indian immigrant presented to the emergency department with hemoptysis. He had had an intermittent productive cough for the past 4 weeks with increasing fatigue and lack of appetite. He also had intermittent fever with drenching night sweats. Chest radiograph and CT scan showed a left upper lobe cavitary lesion with infiltrate. He was admitted to the hospital with concern for pneumonia and to rule out possible active pulmonary tuberculosis.
Background
Active pulmonary tuberculosis (APTB) remains an important but often missed diagnosis in hospitalized patients in the Western world.1,2 Because of its relative rarity, the diagnosis of APTB often is delayed in the United States, which can lead hospitalized patients to nosocomial transmission, unnecessary exposures, patient harm,3 and potentially avoidable cost to the health care system.4 The diagnosis and management can be challenging involving isolation needs, sputum clearance, treatment strategy, and criteria for discharge to home.
Diagnosis
Any patient with risk factors presenting with signs and/or symptoms of APTB such as productive cough for more than 4 weeks, night sweats, weight loss, low-grade fevers, upper lobe cavitary lesions, or hemoptysis should be suspected. The diagnostic work-up for APTB should always begin with a thorough medical and social history. A chest radiograph or a CT scan should always be obtained. Risk factors for infection and for progression to active pulmonary TB are listed below.
Risk factors for TB infection:
- Close contacts of a person with APTB.
- Health care workers.
- Immigrants from high-burden countries.
- Homeless people.
- Individuals who have been incarcerated.
- International travelers.
- HIV patients.
- Intravenous drug users.
Risk factors for progression to APTB:
- HIV infection.
- Intravenous drug use.
- Silicosis.
- Younger than 5 years of age.
- Immunosuppressed.
All patients with suspected or confirmed APTB who cannot be safely discharged home (see discharge considerations below) should be kept in negative-pressure airborne isolation rooms. Isolation can be discontinued once APTB has been ruled out or the patient is determined to be noninfectious based on three consecutive negative sputum smears.
Although rapid and inexpensive, acid-fast bacilli (AFB) smear microscopy has poor sensitivity (45%-80%, with culture-confirmed APTB cases) and poor positive predictive value (50%-80%) for TB in settings in which nontuberculous mycobacteria are commonly isolated. This makes an AFB smear nondiagnostic in the early diagnosis of APTB. The burden of mycobacteria seen in the sputum smear correlates with infectivity.
To improve sensitivity of testing, it is strongly recommended that three AFB smears be completed in 8- to 24-hour intervals and positive smears be accompanied by nucleic acid amplification (NAA) testing.5 If APTB is suspected, but the patient is unable to expectorate, induced sputum samples should be obtained, and, if unable to induce sputum samples, flexible bronchoscopy sampling should be pursued especially for the high-risk populations described above.
The Centers for Disease Control and Prevention recommends that at least one sputum specimen be tested with NAA to expedite the time to diagnosis of APTB. A negative NAA does NOT rule out TB. The turnaround time for this test is about 24-48 hours. NAA has better positive predictive value (greater than 95%) with AFB smear-positive specimens in settings in which nontuberculous mycobacteria are common. The ability to confirm rapidly the presence of Mycobacterium tuberculosis is 50%-80% in AFB smear-negative, culture-positive specimens.6
In patients with clinical or radiologic suspicion of APTB who are unable to produce sputum or have negative sputum smear microscopy results, bronchoscopy is a safe and reliable method for the diagnosis of pulmonary tuberculosis. For the diagnosis of tuberculosis, bronchoalveolar lavage has a sensitivity and specificity of 60% and 100%, respectively. Adding transbronchial biopsy further increases the sensitivity to 84%, and post-bronchoscopy sputum smear microscopy increases the sensitivity to 94%.6
In 2005, the CDC released guidelines for using interferon-gamma release assays (IGRA) to test for M. tuberculosis infection.7 Both tuberculin skin testing (TST) and IGRAs assess lymphocytes’ response to M. tuberculosis. Although these tests can be supportive of a previous tuberculosis infection, they are not diagnostic tests for APTB. Neither an IGRA nor a TST can distinguish latent from active tuberculosis.
Sputum AFB culture remains the preferred method for laboratory confirmation of APTB. Once APTB is confirmed, it is essential for susceptibility testing and genotyping. However, in the absence of a positive culture, APTB can be diagnosed based on signs and symptoms alone in a high-risk patient.
Treatment
A multidisciplinary, patient-centered approach involving the patient, providers, and public health officials is required to accomplish the following treatment goals: eradicating Mycobacterium infection, eliminating the risk of transmission, avoiding the disease, and preventing drug resistance.8
Infectious disease consultation is mandatory in all HIV-positive and suspected or confirmed multidrug-resistant cases. Directly observed therapy is an essential component of APTB treatment to ensure compliance in many situations.
Admission and discharge
Admission to a hospital is not required unless a patient meets criteria for admission independent of APTB diagnosis, or proper risk stratification and assessment cannot be completed in a timely manner. A patient with suspected APTB should be placed in airborne isolation. All staff should wear N95 disposable masks or respirators while inside the patient’s room.9
Discharge considerations are listed below:
- Inform the department of health (DOH).
- Establish proper isolation precautions to minimize exposure.
- Ensure ability to stay at home until DOH and physician determines noninfectivity.
- Educate the patient about length of therapy, directly observed therapy, side effects and importance of compliance.
- Coordinate discharge with the DOH.
- Make sure proper follow-up is scheduled.
Back to the case
Our patient was placed on airborne respiratory isolation immediately upon admission and sputum was sent for AFB. Sputum smear was positive for AFB as well as a positive nucleic acid testing for Mycobacterium tuberculosis. HIV antibody testing was negative. Once the sputum AFB was determined to be positive, the department of health was informed. He was started on the intensive phase of therapy with pyrazinamide, rifampin, ethambutol, and isoniazid along with pyridoxine. He tolerated his medications well and had no immediate reactions. His family and close contacts were screened and advised to be tested.
The patient was discharged after proper follow-up with primary care doctor was scheduled. The department of health arranged for directly observed therapy. He received information about the importance of taking all of his medications and staying at home except for medical visits until the DOH had deemed him to be noninfectious.
Bottom line
APTB in the hospital is an uncommon but serious problem in certain populations. It requires a high index of suspicion and a multidisciplinary approach for effective treatment and prevention of transmission.
Dr. Mallampalli is an attending physician in hospital medicine at Geisinger in Danville, Pa., and clinical assistant professor at Temple University, Philadelphia. Dr. Velidi is an attending physician in hospital medicine at Geisinger. Dr. Courtney is associate director of the department of hospital medicine at Geisinger.
References
1. Miller AC et al. Missed opportunities to diagnose tuberculosis are common among hospitalized patients and patients seen in emergency departments. Open Forum Infectious Diseases. 2015. doi. org/10.1093/ofid/ofv171.
2. Greenaway C et al and the Canadian Collaborative Group in Nosocomial Transmission of Tuberculosis. Delay in diagnosis among hospitalized patients with active tuberculosis–predictors and outcomes. Am J Respir Crit Care Med. 2002 Apr;165:927-33.
3. Medrano BA et al. A missed tuberculosis diagnosis resulting in hospital transmission. Infect Control Hosp Epidemiol. 2014 May;35(5):534-7.
4. Kelly AM et al. Delayed tuberculosis diagnosis and costs of contact investigations for hospital exposure: New York City, 2010-2014. Am J Infect Control. 2017 May 1;45(5):483-6.
5. Lewinsohn DM et al. Official ATS/IDSA/CDC Clinical Practice Guidelines: Diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017 Jan;64:111-5.
6. Mazurek GH et al. Guidelines for using the QuantiFERON-TB Gold test for detecting Mycobacterium tuberculosis infection, United States. MMWR Recomm Rep. 2005 Dec 16;54(RR-15):49-55.
7. CDC. Trends in tuberculosis – United States, 2010. MMWR Morb Mortal Wkly Rep. 2011 Mar 25;60(11):333-7.
8. Jensen PA et al. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep. 2005 Dec 30;54(RR-17):1-141.
9. Siegel JD et al and the Health Care Infection Control Practices Advisory Committee. 2007 Guideline for isolation precautions: Preventing transmission of infectious agents in health care settings. Am J Infect Control. 2007 Dec;35(10 Suppl 2):S65-164.