In vitro drug resistance and response to therapy in pulmonary tuberculosis patients under a DOTS programme in south India

Tuberculosis (TB) patients (n=605) whose pre-treatment sputum culture yielded Mycobacterium tuberculosis were studied for the association of in vitro resistance to anti-TB drugs and treatment outcome. Five hundred and fifty-four (92%) patients showed favourable outcome, while 51 (8%) showed unfavourable outcome to anti-TB treatment. Logistic regression analysis of the data revealed that male gender (Wald P=0.026) and multidrug resistance (MDR) (Wald P<0.001) were associated with unfavourable outcome. Proportion of treatment failure (6%) was higher in patients who had received earlier anti-TB drug therapy (re-treated patients) compared with the newly diagnosed patients (2%). Re-treated patients yielded more drug-resistant M. tuberculosis, including MDR (P<0.001), than new cases. Treatment guided by in vitro drug susceptibility tests may therefore be more effective and less expensive for such selected cases.