Objective: To evaluate adherence to components of the Centers for Disease Control and Prevention (CDC) guidelines for preventing the transmission of Mycobacterium tuberculosis in healthcare facilities.
Design: Multihospital study using direct observation and a standardized questionnaire.
Setting: Three urban hospitals (two county hospitals and one private community hospital) in counties in California with a high number and incidence rate of tuberculosis (TB) cases.
Measurements: The ventilation performance of treatment and TB-patient isolation rooms was assessed. Questionnaire data regarding TB control policy and procedures were obtained through interviews with the person(s) responsible for each program component; review of written TB control plans, training, and educational materials; and attendance at hospital TB control meetings and trainings.
Results: Twenty-eight percent of isolation rooms tested (7/25) were under positive pressure; 83% of rooms tested (20/24) had six or more nominal air changes per hour (ACH), but supply air did not mix rapidly with room air. Therefore, the nominal ACH likely overestimated the effective ACH and the subsequent protection provided. In virtually all rooms tested (26/27), air potentially containing M tuberculosis aerosol moved toward, rather than away from, likely worker locations. None of the hospitals regularly checked the performance of engineering controls. Only one hospital adhered to the CDC minimum requirements for respiratory protection. Training of healthcare workers generally was underutilized as a TB prevention measure. Hospitals did not provide comprehensive counseling regarding the need for healthcare workers to know their immune status and the risks associated with M tuberculosis infection in an immunocompromised individual. Employee representatives did not have a voice in TB-related decision making.
Conclusions: Important aspects of day-to-day TB control practice did not conform to the written TB control policy. Subsequent to the identification of TB patients, healthcare workers at all three hospitals were potentially exposed to M tuberculosis aerosol due to breaches in negative-pressure isolation, the limitations of dilution ventilation, and the failure to maintain engineering controls and to implement respiratory protection controls fully. These findings lend support to the Occupational Safety and Health Administration's policy presumption that, absent clear evidence to the contrary, newly acquired healthcare-worker M tuberculosis infections are work-related.