Primary drug resistance to anti-tuberculous drugs in Karachi.

OBJECTIVE To assess the frequency of primary drug resistance among newly diagnosed tuberculosis cases in Karachi. STUDY DESIGN Cross-sectional study. PLACE AND DURATION OF STUDY Multicentric study involving various TB clinics and treatment centres of Karachi between April to December 2005. METHODOLOGY The frequency of drug resistance among new TB patients was evaluated using a non-probability convenient sampling methodology. Sputum sample was obtained from 140 newly diagnosed sputum smear-positive patients of pulmonary tuberculosis from various centres of Karachi. Sensitivities were performed by proportion method. RESULTS Fifteen (11.5%) samples in 130 eligible patients showed primary resistance to one or more drugs. Ten (7.6%) of the isolates tested were resistant to a single drug, none were resistant to 2 drugs, 4 (3.0%) to 3 drugs and 1 (0.76%) to 4 drugs while 1 (0.76%) to all 5 first line agents. Resistance to streptomycin (10 microg/ml) was seen in 8 (6.1%), isoniazid (1microg/ml) in 12 (9.2%), Rifampicin (5 microg/ml) in 4 (3.0%), ethambutol (10 microg/ml) in 1 (0.76%) and pyrazinamide in 6 (4.6%) samples. Primary Multi-Drug Resistance (PMDR) was found in 2 (1.5%) patients. (Isoniazid 1 microg/ml, rifampicin 5 microg/ml with or without other drugs). CONCLUSION In the studied patients, primary drug resistance to at least one anti-tuberculosis drug was 11.5%. It requires an efficiently working anti-tuberculosis programme to prevent escalation including resistance.