Resistencia adquirida del M tuberculosis a las drogas antibacilares en Chile 1988 y 1991.

Acquired drug resistance appears in patients that are or have been in treatment for tuberculosis (relapses, abandons and failures). The aim of this study was to maintain an epidemiologic surveillance on the incidence of acquired drug resistance among previously treated patients and treatment failures. In 896 strains (518 in 1988 and 378 in 1991) coming from these type of patients, the pattern of sensitivity towards agents used in the treatment of tuberculosis was studied. There was an increase in the frequency of acquired resistance from 24.5% in 1988 to 32.3% in 1991. This increment was observed in the group of treatment failures, where the resistance to the combination streptomycin-isoniazid-rifampin had special relevance. This situation is epidemiologically and clinically negative since it generates primary resistance and chronicity. The increment in acquired resistance forces a revision of tuberculosis treatment, specially in its operational features.