Pattern of Drug-resistance and Treatment Outcome in Multidrug-resistant Pulmonary Tuberculosis

AIMS AND OBJECTIVES: To study the pattern of drug-resistance and treatment outcomes among patients with confirmed multidrug-resistant pulmonary tuberculosis (MDR-PTB). METHODS: A prospective study was conducted at Rajiv Gandhi Institute of Chest Diseases, Bengaluru, Karnataka, India. Between January 2005 and December 2008, 224 confirmed MDR-PTB cases were studied for various drug-resistance patterns, and their treatment outcomes were analysed until November 2010. Sputum culture and drug sensitivity tests (DST) were carried out at National Tuberculosis Institute, Bengaluru; DST was done for all first-line drugs except pyrazinamide. RESULTS: Of the 224 MDR-PTB patients, 146 (65.2%) were resistant to all first-line drugs, 39 (17.4%) to isoniazid, rifampicin and streptomycin; 19 (8.5%) to isoniazid, rifampicin and ethambutol; and 20 (8.9%) to isoniazid and rifampicin. Among them, 145 (64.7%) patients were cured, 5 (2.2%) had treatment-failure, 10 (4.4%) died, and 64 (28.5%) defaulted. Among 145 cured cases, 100 (69%) were resistant to all first-line drugs, 23 (16%) to isoniazid, rifampicin and streptomycin, 11(8%) to isoniazid, rifampicin and ethambutol, and 11(8%) to isoniazid and rifampicin. CONCLUSIONS: The most common pattern observed in this study was resistance to all four first-line drugs followed by resistance to isoniazid, rifampicin and streptomycin. Patients resistant to all first-line drugs had early sputum culture conversion and better cure rate as compared to other resistance patterns.