EPIDEMIOLOGY OF MYCOBACTERIUM-TUBERCULOSIS STRAINS IN SAN-FRANCISCO THAT DO NOT CONTAIN IS6110

ISG110 is commonly used as the basis for molecular epidemiologic and d iagnostic studies of Mycobacterium tuberculosis. However, strains that do not contain ISG110 have been reported. If common, such strains wou ld pose a limitation for molecular studies of M. tuberculosis. Analysi s of a population-based sample from San Francisco of 1569 specimens su bmitted for fingerprinting demonstrated that the proportion of strains that lack ISG110 is less than 1%. While this low percentage permits I S6110 fingerprinting in San Francisco, it may be problematic in other settings.