Nosocomial Tuberculosis1,2

Abstract

Hospital employees are at risk of contracting tuberculosis from patients. The undiagnosed case with sputum-smear positive for acid-fast bacilli is the usual source case. However, even the smear-negative patient may pose a risk. This was documented by a high rate of skin test conversion in hospital staff exposed to a smear-negative, culture-positive patient in a respiratory intensive care unit. The patient required bronchoscopy, intubation, and assisted ventilation. Of susceptible hospital staff members who were exposed to the index case, 14 of 45 (31 %) converted their PPD skin test. Ten of 13 (77%) susceptible hospital staff members present at the time of bronchoscopy converted, compared with 4 of 32 (12.5%) who were not present at bronchoscopy (Fischer’ s exact test p = 0.00006). Rough calculations suggest that during the bronchoscopy and intubation the index case generated at least 249 infectious units per hour. At the ventilation levels in this area, this resulted in 1 infectious unit of tuberculosis ...