Drug susceptibility profiles of Mycobacterium tuberculosis isolates from Gulbarga, South India

Drug resistance surveillance is a useful tool to assess the effective functioning of tuberculosis (TB) control program. This study was undertaken to know the first line anti tuberculosis drug susceptibility profile of Mycobacterium tuberculosis clinical isolates from the Gulbarga district of South India. Drug susceptibility test was performed for 102 clinical isolates of M. tuberculosis belonging to new (n=62), treated (n=22) and unknown treatment category (n=18) of TB. All the isolates were tested for susceptibility to first line anti-tuberculosis drugs by minimum inhibitory concentration (MIC) and resistance ratio method (for streptomycin). The susceptibility profile of M. tuberculosis to all five first line anti-tubercular drugs was found to be 60.78% (62/102). Overall, multi drug resistance (resistance to at least isoniazid and rifampicin) was observed in 8.82% (9/102) isolates and was found to be higher for treated cases (18.18%). High level of drug resistance observed in new cases for isoniazid, rifampicin and ethambutol suggests need for the implementation of drug resistance surveillance studies in order to document the success of the tuberculosis control program in reducing the level of drug resistance.