Application of ATP assay for in vitro drug screening testing against human derived M. leprae

In this study, the ATP content of M. leprae exposed to various antimicrobial agents has been measured to evaluate its usefulness in drug sensitivity screening. Purified M. leprae suspensions from human biopsies have been incubated at 30 degrees C in a modified Dubos medium in the presence of different concentrations of various drugs viz., Rifampicin, Ethionamide, Ethambutol, Cycloserine, Dapsone, Clofazimine, Erythromycin and Tetracycline. ATP levels were estimated at 0, 7 days, 14 days of incubation by the procedures modified and standardised at this laboratory. ATP decay was accelerated by ethionamide, rifampicin, clofazimine, dapsone, erythromycin and to a lesser extent by cycloserine, whereas ethambutol and tetracycline did not have any significant effect. The rate of decay depended on the concentrations of these drugs. ATP assay promises to be a useful system for in vitro drug sensitivity screening against M. leprae isolated from patients.