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

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. 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. Cross-sectional study. 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/m³ 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. 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. .

Inadequate ventilation for nosocomial tuberculosis prevention in public hospitals in Central Thailand.

SETTING: Forty-two community and general hospitals in central Thailand. OBJECTIVE: To examine the adequacy of indoor ventilation for nosocomial tuberculosis (TB) prevention in public hospitals in central Thailand. DESIGN: A cross-sectional survey was conducted among 323 patient care and ancillary areas in the target hospitals. Data on indoor ventilation rate were collected by the tracer gas method and reported as air changes per hour (ACH). The adequacy of the measured ventilation rates were then determined by comparison with the international recommended standard values. RESULTS: Indoor ventilation rates were inadequate in almost half of the studied areas (144/323, 44.6%). The inadequacy was particularly serious in the emergency rooms (ERs) and radiological areas, where 73.8% (31/42 each) of the rooms had ACH below the recommended standards. Detailed analysis showed that most of the rooms with natural ventilation had air exchange rates that exceeded the recommended standards, while the opposite was the case for rooms with air-conditioning, particularly the window or wall-mount type. CONCLUSION: Indoor ventilation in high-risk nosocomial TB areas in public hospitals in Thailand was inadequate due to the installation of air-conditioning systems in modern buildings.