Rifampicin resistant leprosy: a review and a research proposal of a pilot study.

Twenty years ago, dapsone resistance had become so widespread a phenomenon among both treated and untreated leprosy patients, that the achievements of leprosy control obtained during the preceding 30 years by large scale dapsone monotherapy were in serious jeopardy. To avert the further spread of dapsone resistance, immediate implementation of multidrug therapy (MDT) was recommended by the WHO Study Group for the treatment of both paucibacillary (PB) and multibacillary (MB) leprosy patients. The MDT regimens for both PB and MB leprosy contain rifampicin (RMP). Compared with the other components of the MDT regimens, i.e. dapsone (DDS) and clofazimine (CLO), RMP is far more bactericidal against Mycobacterium leprae in mice and in humans. In fact, the bactericidal effect of RMP is greater than that of any combination of the new drugs, o ̄oxacin, clarithromycin and minocycline; thus, RMP is the backbone of the MDT regimens. Emergence of RMP resistance would create very great dif®culties for the treatment of individual patients; its widespread dissemination would pose a serious threat to reaching the leprosy elimination target.