Mycobacterium tuberculosis DNA not detected by polymerase chain reaction in air samples from hospital rooms of tuberculosis patients

Background: As the incidence of tuberculosis (TB) increased in the United States, the risk of occupational and nosocomial TB also increased. Airborne Mycobacteriitm tuberculosis (MTB) is difficult to measure directly. Quantifying MTB DNA by polymerase chain reaction in air samples obtained from isolation rooms of patients with TB would provide a measure of the number of airborne organisms produced by a patient and the efficacy of ventilation, and might predict when an individual patient is no longer infectious. Methods and Results: The air was sampled through cellulose ester filters from the isolation room of a patient with newly diagnosed pulmonary TB, from a patient on therapy for TB for 14 days, and from adjacent offices, and an attempt was made to detect MTB DNA; however, MTB DNA was detected only on positive control filters. Conclusions: Mycobacteriiim tuberculosis was not detected by polymerase chain reaction in air samples from the rooms of two patients with pulmonary TB. This may have been due to the large number of room air changes with resultant rapid clearance of airborne droplet nuclei or to the limited air volume sampled. A sensitive molecular assay of airborne MTB could be used to monitor the efficacy of infection control measures by sampling a sufficient volume of isolation room air and could aid in determining when an individual patient was no longer infectious.