Detection of airborne Mycobacterium tuberculosis complex in high-risk areas of health care facilities in Thailand

SETTING : In high-risk areas (sputum collection room in a tuberculosis [TB] clinic, patient rooms in a TB ward, the emergency department and the bronchoscopy unit) in seven health care facilities located in central Thailand. OBJECTIVE : To detect airborne Mycobacterium tuberculosis complex and other environmental parameters using the liquid impinger and real-time quantitative polymerase chain reaction (real-time qPCR) technique in high-risk areas. DESIGN: Cross-sectional study. RESULTS : M. tuberculosis was detected in 3 of 99 (3.0%, 95% CI 0.6-8.6) areas: one sputum collection room and one TB in-patient room in one facility and one sputum collection room in another facility. In these three areas, the M. tuberculosis copy number/m(3) ranged from 9.6 to 1671. Lower air change rate (<6 h(-1)), higher relative humidity (>65%), and contact with coughing patient(s) were more common in airborne M. tuberculosis-positive areas than in M. tuberculosis-negative areas. CONCLUSIONS : Air sampling using a liquid impinger followed by real-time qPCR is effective for quantitative detection of airborne M. tuberculosis in high-risk areas. Our findings indicate TB risk among health care workers, and suggest that improved ventilation, enhanced appropriate cough etiquette and respiratory protection are needed to mitigate M. tuberculosis transmission.