A NOSOCOMIAL OUTBREAK OF MULTIDRUG-RESISTANT TUBERCULOSIS

Background: An outbreak of seven cases (in six patients and one health care worker, all of whom had AIDS) of multidrug-resistant tuberculosi s occurred in a hospital in Chicago. The hospital had a respirator-fit testing program but no acid-fast bacilli isolation rooms. Objective: To identify risk factors for transmission of Mycobacterium tuberculosi s. Design: Retrospective cohort study. Setting: Private hospital. Part icipants: Patients and health care workers exposed to M. tuberculosis. Measurements: Analysis of M. tuberculosis isolates, tuberculin skin t esting, assessment of exposure, and assessment of participant characte ristics. Results: All seven M. tuberculosis isolates had matching DNA fingerprints. Of patients exposed to M. tuberculosis, those who develo ped tuberculosis had lower CD4(+) T-lymphocyte counts (P = 0.02) and w ere more likely to be ambulatory (P = 0.03) than those who did not. Of 74 exposed health care workers, the 11 (15%)who had conversion on tub erculin skin testing were no more likely than those who did not have c onversion to report that they always wore a respirator with a high-eff iciency particulate air filter. Conclusions: Transmission of M. tuberc ulosis occurred in a hospital that did not have recommended isolation rooms. A respirator-fit testing program did not protect health care wo rkers in this setting.