TUBERCULOSIS IN HEALTH-CARE WORKERS AT A HOSPITAL WITH AN OUTBREAK OFMULTIDRUG-RESISTANT MYCOBACTERIUM-TUBERCULOSIS

Objective: Investigate reports of tuberculosis in health care workers employed at a hospital with an outbreak of multidrug-resistant Mycobac terium tuberculosis. Design: Case series of tuberculosis in health car e workers, January 1, 1989, through May 31, 1992. Antimicrobial suscep tibility testing and restriction fragment length polymorphism analysis of M tuberculosis isolates. Longitudinal analysis of cumulative tuber culin skin test surveillance data. Assessment of infection control. Th e patients consisted of 361 health care workers who had either serial tuberculin skin tests or tuberculosis. Results: Six health care worker s, the largest number linked to one multidrug-resistant tuberculosis o utbreak, had disease due to M tuberculosis that matched the outbreak s train from hospitalized patients. The two who were seropositive for hu man immunodeficiency virus died, one of tuberculous meningitis and the other of multiple causes including tuberculosis. The estimated risk o f a skin test conversion was positively associated with time and incre ased by a factor of 8.3 (1979 to 1992). In 1999 the annual risk for wo rkers in the lowest exposure occupational group was 2.4%. In compariso n, nurses and housekeepers had relative risks of 8.0 (95% confidence i nterval, 3.2 to 20.3) and 9.4 (95% confidence interval, 2.7 to 32.3), respectively. laboratory workers had a relative risk of 4.2 (95% confi dence interval, 1.1 to 15.5). Tuberculosis admissions increased, but t he hospital had inadequate ventilation to isolate tuberculosis patient s effectively. There were lapses in infection control practices. Concl usions: Health care workers who were exposed during a hospital outbrea k of multidrug-resistant tuberculosis had occupationally acquired acti ve disease. The human immunodeficiency virus-infected health care work ers with tuberculosis had severe disease and died. The risk of skin te st conversion increased during the study period, and higher exposure o ccupations had elevated risk. Effective infection control is essential to prevent the transmission of tuberculosis to health care workers.