Tuberculosis (TB) infection control guidelines
Queensland Health recommends all health-care settings have an infection control program to ensure prompt detection, implementation of airborne precautions and treatment of people who have suspected or confirmed tuberculosis (TB) disease.
There are three levels of TB infection control in health-care settings:
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administrative (eg. minimise the number of areas where exposure to TB may occur)
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environment (eg. isolate patient from waiting areas, negative-pressure rooms and sputum induction rooms where cough-producing procedures are performed)
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respiratory protective equipment (eg. particulate filter masks N95).
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Incubation period
Following significant exposure, it generally takes two to ten weeks before a TB infection can be detected by a tuberculin skin test.
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Transmission
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A sputum ‘smear positive’ result for acid-fast bacilli on direct microscopy is an indication of active, infectious disease.
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Tubercle bacilli are carried in airborne ‘droplet’ nuclei, dispersed into the aerial environment when someone with active disease (ie. sputum smear positive) generates sputum through coughing, sneezing, talking or singing. Nuclei are also spread during sputum induction, suctioning and bronchoscopy. The nuclei remain suspended in the air for long periods and are able to move via air currents.
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The risk of transmission to people exposed to risk of inhalation of droplet nuclei depends on the concentration of infectious nuclei in the air and the duration of unprotected exposure to contaminated air.
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The infectivity of patients with multi-drug-resistant tuberculosis or those given sub-optimal treatment for tuberculosis should be considered on an individual basis and discussed with an expert in this field.
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Prevention and management
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All health care facilities are advised to develop their own risk stratification protocols to facilitate the identification of potentially active cases of tuberculosis. This includes maintaining a high index of suspicion, and collection of sputum to detect acid fast bacilli, and chest x-ray.
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Infectious and potentially infectious patients require airborne precautions in hospital.
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Airborne precautions can be ceased when: diagnosis excludes active tuberculosis; or when three adequately collected sputum specimens are consecutively negative for acid fast bacilli on direct microscopy; or when the patient has received appropriate treatment for two weeks for an isolate found to be fully sensitive to isoniazid and rifampicin and has demonstrated clinical improvement.
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If a patient with a fully drug-sensitive isolate remains sputum smear positive for AFB despite two weeks of compliance with appropriate therapy, a clinician specialised in TB management should be consulted prior to ceasing airborne precautions.
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Protocols should be in place to minimise transmission of tuberculosis in units performing sputum induction and bronchoscopy.
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The QTBCC building in Brisbane is equipped with a state-of-the-art air management system to minimise risk to staff, patients and visitors The clinical floor has a directional air flow system that is HEPA filtered and disinfected by ultraviolet light prior to recirculation/venting. A sputum induction booth is also available which is negatively pressured, HEPA filtered and disinfected by ultraviolet light.
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References
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