Minimum inhibitory concentration of drugs against Mycobacterium leprae as determined by an in vitro assay.

ABSTRACT

The observations that live Mycobacterium leprae after entry into cultured peritoneal macrophages from mice, reduced the EA rosetting macrophages, have been exploited to determine the minimum inhibitory concentration of diamino diphenyl sulphone and rifampicin. Diamino diphenyl sulphone showed a minimum inhibitory concentration of 0·028 μg/ml and rifampicin 0·11 μg/ml when given externally. However, there was accumulation of diamino diphenyl sulphone inside the macrophages. At an external concentration of 0·028 μg/ml the concentration inside the macrophage was 0·5 μg/ml. The minimum inhibitory concentration for diamino diphenyl sulphone in this assay system is higher by several folds and that for rifampicin is slightly lower, than what is reported earlier with mice foot pad experiments. The minimum inhibitory concentration reported in this assay system is quite close to what is observed for in vitro inhibition of Mycobacterium lufu with both the drugs.