The rates of resistance to second-line drugs in multidrug resistant Mycobacterium tuberculosis strains

The treatment of multidrug resistant tuberculosis (MDR-TB) requires the use of minor antituberculosis drugs, thus susceptibilities against these minor drugs should be performed. The aim of this study was to establish and standardize the susceptibility testing methods for minor antituberculosis drugs in this laboratory and to obtain data about the resistance rates. Drug susceptibility tests were performed by proportion method in Lowenstein-Jensen media for 50 MDR Mycobacterium tuberculosis isolates that have been collected from different regions of our country. Resistance rates to ethionamide, cycloserin, kanamycin, p-aminosalicylic acid, ofloxacin, thiacetasone, and capreomycin were found as 22%, 8%, 6%, 6%, 2%, 2%, and 0%, respectively. Multidrug resistance was observed in 8% of the isolates. As a result, the resistance rates of multidrug resistant M. tuberculosis strains against the tested minor antituberculosis drugs seem to be low in this study.