Nosocomial transmission of tuberculosis in a hospital unit for HIV-infected patients

Abstract

Objective: To assess nosocomial transmission of tuberculosis (TB).

Design: A historical cohort study of hospitalized patients with the human immunodeficiency virus (HIV) and a purified protein derivative (PPD) tuberculin skin test survey of health care workers (HCWs).

Setting: A large public teaching hospital in San Juan, Puerto Rico.

Patients: For the cohort study, a case patient was defined as any patient in the HIV unit at the hospital who developed culture-positive TB from 31 days or more after admission through December 31, 1989. For the PPD survey, of 1420 HCWs from the hospital, 908 agreed to participate and had sufficient data for analysis.

Main outcome measures: For the cohort study, to compare the risk of developing active TB among patients who were exposed to hospital roommates with infectious TB and the risk among nonexposed patients. For the HCW PPD survey, to determine the prevalence of and risk factors for tuberculous infection.

Results: Eight of 48 (9.7/10,000 person-days) exposed case patients vs four of 192 (0.8/10,000 person-days) nonexposed case patients developed active TB (relative risk [RR] = 11; 95% confidence interval [CI], 2.3, 50.3). Positive PPDs (greater than or equal to 10 mm of induration) in HCWs were associated with older age (P = .0001) and with history of community TB exposure (P = .0002). In a multivariable logistic model that adjusted for these variables, HIV unit nurses (nine of 19) and nurses in the internal medicine ward (45 of 90) had a higher proportion of positive PPDs than the reference group (clerical personnel on other floors: 35 of 188, P = .0005).

Conclusions: These data suggest that patient-to-patient transmission of TB in HIV units can occur and that HCWs are at risk of acquiring TB infection.