A CITY-WIDE OUTBREAK OF A MULTIPLE-DRUG-RESISTANT STRAIN OF MYCOBACTERIUM-TUBERCULOSIS IN NEW-YORK

SETTING: Incident patients with active tuberculosis (TB) resistant to two or more drugs in New York City hospitals in 1992. OBJECTIVE: To ex amine the New York-wide distribution of Public Health Research Institu te (PHRI) strain W of Mycobacterium tuberculosis, an extremely drug-re sistant strain identified by a 17-band Southern hybridization pattern using IS6110, during the peak tuberculosis year of 1992. We also compa red strain W with other strains frequently observed: in New York. DESI GN: Blinded retrospective study of stored M. tuberculosis cultures by restriction fragment length polymorphism (RFLP) DNA fingerprinting, an d chart review. RESULTS: We found 112 cultures with the strain W finge rprint and 8 variants in 21 hospitals among incident patients hospital ized in 1992. Almost all isolates were resistant to four first-line dr ugs and kanamycin. This single strain made up at least 22% of New York City multiple-drug-resistant (MDR) TB in 1992, far more than any othe r strain. Almost all W-strain cases were acquired immune deficiency sy ndrome (AIDS) patients. The cluster is the most drug-resistant cluster identified in New York and the largest IS6110 fingerprint cluster ide ntified anywhere to date. CONCLUSION: Because recommended four-drug th erapy will not sterilise this very resistant strain, there was a city- wide nosocomial outbreak of W-strain TB in the early 1990s among New Y ork AIDS patients. Other frequently seen strains were either also very resistant, or, surprisingly, pansusceptible. Individual MDR strains c an be spread widely in situations where AIDS and TB are both common.