TUBERCULOSIS AMONG URBAN HEALTH-CARE WORKERS - A STUDY USING RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM TYPING

Cases of tuberculosis identified during 1992-1994 through an active tu berculosis surveillance network among six hospitals that serve New Yor k City (the TBNetwork) were analyzed according to the occupational sta tus of the patients. Clinical data were obtained by review of medical records, and restriction fragment length polymorphism (RFLP) typing of Mycobacterium tuberculosis isolates was performed. No known nosocomia l outbreaks of tuberculosis occurred at these hospitals in the study p eriod. Occupational status was known for 142 of 201 patients whose iso lates were available for strain typing. Patients infected by organisms with a clustered strain typing pattern, as determined by RFLP analysi s, were presumed to have recently acquired disease, RFLP typing reveal ed that isolates from 13 (65%) of 20 health care workers and 50 (41%) of 122 non-health care workers had a clustered RFLP pattern. The strai ns infecting eight (89%) of nine health care workers seropositive for human immunodeficiency virus (HIV) had a clustered RFLP pattern, Multi variate analysis of 75 patients with known HIV and occupational status revealed that HIV status (P = .03) and health care worker status (P = .02; RR = 2.77) were independent risk factors for a clustered RFLP st rain. These findings suggest that many of the apparently sporadic case s of tuberculosis among health care workers may be due to unrecognized occupational transmission.