Mycobacterium tuberculosis is spread through infectious droplet nuclei. When a person infected with pulmonary tuberculosis coughs, sneezes, or talks, the infectious particles are expelled into the air. The risk of infection is related to both concentration of infectious droplet nuclei and duration of exposure.
Clinical laboratory workers are at risk when an infectious aerosol is generated while handling liquid cultures, during preparation of frozen sections, and during the performance of autopsies on infected patients.
