The risk for transmission of Mycobacterium tuberculosis at the bedside and during autopsy.

Abstract

OBJECTIVE: To emphasize the differing infectious potentials of a patient with tuberculosis. SETTING: Hospital ward and autopsy room. DESIGN: An epidemiologic investigation of tuberculin skin test conversions in a clinical setting and during autopsy when results of tuberculin tests done before exposure were available for all participants. MEASUREMENTS: Tuberculin skin test results after the discovery of tuberculosis exposure from a patient with unsuspected tuberculosis for comparison with the test results before exposure; culture of sputum and autopsy material for Mycobacterium tuberculosis; and DNA fingerprinting of organisms. INTERVENTION: Preventive therapy for persons with skin test conversion. RESULTS: None of the 40 skin test-negative health care workers caring for the patient for 3 weeks on an open medical ward showed a skin test conversion, even though they had not used respiratory precautions. By contrast, among personnel present during the 3-hour autopsy, the test results of all five nonreactors converted from negative to positive (mean reaction, 24 mm). Two of these persons had a positive sputum culture 8 weeks later. The DNA fingerprints of all three isolates were identical. CONCLUSIONS: A patient who did not transmit tuberculosis before death released a prodigious number of tubercle bacilli during autopsy.