Low rate of emergence of drug resistance in sputum positive patients treated with short course chemotherapy.
METHODS
Tuberculosis Research Centre, Chennai.


OBJECTIVE
To study the emergence of drug resistance during treatment and relapse among sputum positive pulmonary tuberculosis patients treated with short-course chemotherapy regimens.


METHODS
Retrospective analysis of randomised clinical trials using the following regimens: 2HRZE7/6HE7, 2HRZE2/4HRE2, 2HRZE3/4HR2 and 3HRZE3/3HR2. Emergence of resistance was analysed in patients with unfavourable response/relapse based on culture and susceptibility reports.


RESULTS
Of 1817 patients studied, 1435 (79%) had susceptible strains prior to treatment; 2% of these had an unfavourable response, 7% relapsed and 1% had emergence of resistance to isoniazid, rifampicin, or both. In 320 patients with initial isoniazid resistance, 19% had an unfavourable response and 13% relapsed, while resistance to rifampicin emerged in 11%. Treatment outcomes were similar whether patients received three or two drugs in the continuation phase. Data on resistance to ethambutol and pyrazinamide were not available.


CONCLUSIONS
In this study, the overall emergence of resistance to rifampicin occurred in only 2% of patients, despite the high level (18%) of initial resistance to isoniazid. Thus, standardised short-course treatment carries only a minimal risk of emergence of rifampicin resistance.
D000995:Antitubercular Agents / Q000008:administration & dosage*; D016009:Chi-Square Distribution; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D012189:Retrospective Studies; D012293:Rifampin / Q000008:administration & dosage; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology*; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000453:epidemiology*
D000995:Antitubercular Agents; D012293:Rifampin