Transmission of a multidrug-resistant Mycobacterium tuberculosis strain resembling "strain W" among noninstitutionalized, human immunodeficiency virus-seronegative patients

Since 1990, several outbreaks of multidrug-resistant tuberculosis (MDR-TB) have been described among institutionalized patients infected with human im munodeficiency virus (HIV). We describe a community MDR-TB outbreak among H IV-seronegative patients in Cape Town, South Africa. Isolates were characte rized by restriction fragment length polymorphism (RFLP) analysis and dot-b lot hybridization analysis of mutations conferring resistance for isoniazid , rifampin, streptomycin, and ethambutol, All isolates were identical on RF LP analysis, In 2 patients, RFLP analysis showed exogenous reinfection duri ng or after treatment for drug-susceptible TB, Mutation analysis confirmed the genotypic identity of the isolates. The infecting strain was genotypica lly related to strain W which is responsible for the majority of MDR-TB out breaks in New York City. Transmission of MDR-TB is thus not limited to HIV- seropositive patients in an institutional setting but occurs within a commu nity.