In Vitro Methods for Rapid Monitoring of Drug Therapy and Drug Resistance in Leprosy

Though bacterial etiology of leprosy was suggested in 1873 by Hansen, the progress in understanding the biology of the leprosy bacillus has been very slow. Mycobacterium leprae has not been cultivated in vitro in any acceptable medium system. Growth of M.laprae in animal experiments is useful only at the research level. However, for assessment of the efficacy of drug therapy, repeated monitoring of the load and viability of the bacillus is required which is not possible in the case of leprosy. Nevertheless the progress made in understanding the structure and function of the leprosy bacillus has helped in the development of various morphological, chemical/ biochemical and more recently molecular biological approaches for monitoring the effect of treatment. In this write-up the major advances in this area are discussed under the broad headings: assessment of bacterial load; techniques for in vitro determination of viability; and techniques for in vitro drug sensitivity screening and detection of drug resistance.