TB Manual

Aerosolization of infectious M. tuberculosis bacteria occurs when individuals with respiratory TB cough, sneeze, sing, or speak. Aerosol-generating medical procedures (e.g., bronchoscopy, intubation, sputum induction), and some patient-care activities (e.g., irrigating a mycobacterial-containing wound), laboratory and autopsy procedures can also cause aerosolization of mycobacteria. Once infectious M. tuberculosis bacteria are aerosolized, they may be carried throughout a room or building by air currents and inhaled by another individual, with the possibility of TB infection. Although the risk of transmitting M. tuberculosis is highly variable, the presence of certain factors (discussed in the following sections) predicts an increased transmission risk. In general, the more of these factors present, the greater the risk of M. tuberculosis transmission (see Chapter 2: Transmission and Pathogenesis of Tuberculosis).