Assessment of resistance in multi drug resistant tuberculosis patients.
To study MDR-TB isolates and to identify primary and secondary resistance at microbiology laboratory Aga Khan University, Karachi, Pakistan. All samples positive for Mycobacterium tuberculosis (MTB) received during January - September 2004 were reviewed for drug resistance pattern as well as for history of previous antituberculous drugs exposure. Out of 216 Mycobacterium tuberculosis cultures, 138 (64%) showed resistance to one or more agents. Multi drug resistance (MDR) was observed in 102 (47%) isolates. Of 138 drug resistant isolates; primary resistance to any one or more agent was noted in 31(39%) and secondary (acquired) resistance in 107 (79%) isolates. On analysis of the 102 MDR-TB strains 8 (10%) showed primary resistance while 94 (69%) showed secondary resistance. In this group MDR-TB was mainly associated with previous anti-tuberculous treatment. However, primary MDR was also observed and reflects dissemination of MDR cases within the community.