EXOGENOUS REINFECTION WITH MULTIDRUG-RESISTANT MYCOBACTERIUM-TUBERCULOSIS IN PATIENTS WITH ADVANCED HIV-INFECTION

Background. In the United States there have been recent outbreaks of m ultidrug-resistant tuberculosis. These outbreaks have primarily involv ed persons infected with the human immunodeficiency virus (HIV). Metho ds. We collected clinical information on 17 patients seen at a New Yor k City hospital who had repeatedly positive cultures for Mycobacterium tuberculosis. Analysis of restriction-fragment-length polymorphisms ( RFLPs) was performed on serial isolates of M. tuberculosis obtained fr om these patients. Results. Six patients had isolates that remained dr ug-susceptible, and the RFLP patterns of these isolates did not change over time. Eleven patients had isolates that became resistant to anti microbial agents. The RFLP patterns of the isolates from six of these patients remained essentially unchanged (two strains showed one additi onal band) despite the development of drug resistance. In five other p atients, however, the RFLP patterns of the isolates changed dramatical ly at the time that drug resistance was detected. The change in the RF LP pattern of the isolate from one patient appeared to be the result o f contamination during processing in the laboratory. In the remaining four patients, all of whom had advanced HIV disease, the clinical and microbiologic evidence was consistent with the presence of active tube rculosis caused by a new strain of M. tuberculosis. Conclusions. Resis tance to antituberculous drugs can develop not only in the strain that caused the initial disease, but also as a result of reinfection with a new strain of M. tuberculosis that is drug-resistant. Exogenous rein fection with multidrug-resistant M. tuberculosis can occur either duri ng therapy for the original infection or after therapy has been comple ted.