Surveillance of drug resistance in tuberculosis in two districts of South India

SETTING: Tuberculosis Research Centre, Chennai, India. OBJECTIVES: To determine the levels of drug resistance in new and previously treated cases of pulmonary tuberculosis in the composite districts of North Arcot (Tamil Nadu State) and Raichur (Karnataka State) in South India. DESIGN: Two specimens of sputum from 320 patients attending 23 participating centres in North Arcot district and 314 patients from 20 participating centres in Raichur district were tested for drug susceptibility to isoniazid (H), rifampicin (R), ethambutol (E), streptomycin (S) and ofloxacin (O). The studies were undertaken using the guidelines prescribed by the WHO/IUATLD Working Group on Anti-tuberculosis Drug Resistance Surveillance. RESULTS: In North Arcot district, resistance to any drug tested was found in 27.7% of new cases; any H resistance in 23.4%, any R resistance in 2.8% and multidrug resistance (resistance to at least H and R: MDR) in 2.8%. In previously treated cases, resistance to any drug was observed in 81.2%, and any resistance to H, R and HR in 81%, 69% and 69%, respectively. In Raichur district, resistance to any drug was observed in 21.9% of new cases; any resistance to H, R and HR (MDR) was found in 18.7%, 2.5% and 2.5%, respectively. All previously treated patients were resistant to H and R (100%). CONCLUSION: In North Arcot district, the proportion of MDR-TB in newly diagnosed patients has marginally increased over the last 10–15 years, whereas it has remained fairly constant in Raichur district. An increase in resistance was noted in previously treated cases in both districts, although the numbers of patients are small