Tuberculosis Outbreak in a General Hospital: Evidence for Airborne Spread of Infection

Abstract

Tuberculin skin test conversions in 23 employees of a general hospital were attributed to exposure to a patient with undetected tuberculous bronchopneumonia. Two converters had evidence of active infection, and 21 were asymptomatic. On a ward where the patient spent 57 hours there were 21 converters in 60 tuberculin-negative personnel (35%). Ten had little or no direct contact with the patient and were likely to have been infected by the spread of Mycobacterium tuberculosis through an unbalanced air conditioning system that lacked high-efficiency filters. On a better ventilated ward, where the patient spent 67 hours, conversions occurred in only 2 of 19 personnel at risk (10.6%), and both were in close contact.