Study of the in vitro susceptibility of M. tuberculosis to ofloxacin in Spain. Spanish Study Group of M. tuberculosis resistance.

The aim of this study was to determine the proportion of antituberculosis ofloxacin resistance among Mycobacterium tuberculosis strain isolates in Spain. Over a period of one month, 213 M. tuberculosis strains collected from 14 different hospitals were studied, including strains both susceptible and resistant to primary antituberculosis drugs. In 28.1% of the strains, a minimum inhibitory concentration (MIC) for ofloxacin of 0.25 microg/ml was obtained; in 43.6% the MIC was 0.5 microg/ml; in 22.06% it was 1 microg/ml; and in 6.1% it was > or =2 microg/ml. Ofloxacin currently seems to be an effective antimicrobial in vitro against susceptible or multiresistant strains of M. tuberculosis in human immunodeficiency virus (HIV)-negative or HIV-positive patients in Spain.