Drug susceptibility of Mycobacterium tuberculosis in a rural area of Bangladesh and its relevance to the national treatment regimens

SETTING: Greater Mymensingh District, a rural area of Bangladesh, at the st art of the National Tuberculosis Programme (NTP). OBJECTIVES: To determine the prevalence of initial and acquired drug resist ance of Mycobacterium tuberculosis, and to assess the appropriateness of th e NTP's standard regimens. DESIGN: Sampling of pre-treatment sputum from all newly registered smear-po sitive cases in five centres covering the area. Culture and susceptibility testing in a supra-national reference laboratory RESULTS: Initial resistance to isoniazid (H) was 5.4%, and to rifampicin (R ) 0.5%. Acquired H and R resistance were 25.9% and 7.4%, respectively. Mult idrug resistance (MDR) was observed in one new case only and in 5.6% of pre viously treated patients. Changing the present NTP indication for retreatme nt regimen to one month of previous H intake would increase coverage of H-r esistant cases from 52% to 89%, adding 6% to drug costs. CONCLUSION: The prevalence of drug resistance is surprisingly low in Bangla desh, but could rise with improving economic conditions. The NTP regimens f or smear-positive cases are appropriate, all the more so since the human im munodeficiency virus is virtually absent. Indications for the retreatment r egimen should be extended to include all patients treated for at least one month with any drug. The NTP regimen for smear-negative cases runs the risk of leading to MDR under present field conditions.