Study of drug resistance in previously treated tuberculosis patients in Gujarat, India

SETTING: Department of Tuberculosis and Chest Diseases and State Tuberculosis Diagnosis and Training Centre (STDTC), a DOTS centre in Ahmedabad, Gujarat State, India. The study was carried out by retrospectively reviewing patient data between January 2000 and August 2001. OBJECTIVE: To evaluate the pattern of drug resistance among previously treated tuberculosis patients who remained symptomatic or smear-positive despite receiving anti-tuberculosis drugs under DOTS for a minimum of 5 months. DESIGN: A total of 1472 pulmonary tuberculosis patients who had taken anti-tuberculosis treatment were evaluated retrospectively with respect to their drug resistance pattern by sputum culture for acid-fast bacilli (AFB) and sensitivity testing with isoniazid, rifampicin, streptomycin and ethambutol (E). RESULT: Of the 1472 patients evaluated, 804 (54.6%) were treatment failure cases and 668 (45.4%) were relapse cases; 822 patients (373 failure and 449 relapse) were culture-positive. Of these 822 patients, 482 (58.64%, 261 failure and 221 relapse) were resistant to one or more drugs. Resistance to one drug was observed in 86 patients (10.46%), to two drugs in 149 (18.13%), to three drugs in 122 (14.84%) and to four drugs in 125 (15.21%). Single drug resistance was most commonly seen with isoniazid (62 patients, 7.5%), followed by streptomycin (12 patients, 1.4%), rifampicin (eight patients, 0.97%) and ethambutol (four patients, 0.4%). Resistance to isoniazid plus rifampicin alone was seen in 76 patients (9.2%). CONCLUSION: Drug resistance is a major problem in the treatment of pulmonary tuberculosis. Detection of drug resistance patterns and treatment with second-line anti-tuberculosis drugs in appropriate regimens are necessary in the treatment of failure and relapse cases in order to reduce the emergence of multidrug-resistant tuberculosis.