Drug resistance to tuberculosis in a tertiary care setting in Karachi.

OBJECTIVE To evaluate the resistance pattern of tuberculosis cases. METHODS A descriptive study was done in two out patient referral clinics from January 1999 to March 2003. All TB cases that had cultures positive for mycobacterium tuberculosis were evaluated. RESULTS Data from 71 proven culture positive patients was available. Resistance to at least one antituberculous drug was found in 44 (60.5%) cases. Primary, Initial and Secondary Resistance to at least one drug was 7.0%, 21.1% and 32.3% respectively. Out of 7.0% primary resistance cases, there were 5.6% of single drug resistance, 1.4% Multiple Drugs and zero percent of Multi drug Resistance (MDR). Initial resistance cases (out of 21.1%) included 12.6% to single drug, 7% to multiple drugs and 1.4% MDR. Acquired Resistance Cases (out of 32.3%) included 5.6% each to single and multiple drugs and 21% MDR. Single drug resistance (for primary, initial and acquired) showed 14% resistance for Isoniazid, 4.2% for Rifampicin, 2.8% each for Ethambutol and Streptomycin and 1.4% to Pyrazinamide. CONCLUSION In this cohort of patients, Primary resistance to at least one drug was 7.0% and no MDR. Among individual drugs, resistance to Isoniazid was highest (14%) and lowest for Pyrazinamide (1.4%).