RISK FOR TRANSMISSION OF MYCOBACTERIUM-TUBERCULOSIS AT THE BEDSIDE AND DURING AUTOPSY

Objective: To emphasize the differing infectious potentials of a patie nt 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 test s done before exposure were available for all participants. Measuremen ts: Tuberculin skin test results after the discovery of tuberculosis e xposure from a patient with unsuspected tuberculosis for comparison wi th the test results before exposure; culture of sputum and autopsy mat erial for Mycobacterium tuberculosis; and DNA fingerprinting of organi sms. Intervention: Preventive therapy for persons with skin test conve rsion. 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 sk in test conversion, even though they had not used respiratory precauti ons. By contrast, among personnel present during the 3-hour autopsy, t he test results of all five nonreactors converted from negative to pos itive (mean reaction, 24 mm). Two of these persons had a positive sput um culture 8 weeks later. The DNA fingerprints of all three isolates w ere identical. Conclusions: A patient who did not transmit tuberculosi s before death released a prodigious number of tubercle bacilli during autopsy.