ABSTRACT
Resistant strains of M. leprae have been reported to the various antileprosy drugs. There is currently no accepted test to identify the susceptibility pattern of M. leprae to the drugs in a short period. The only accepted test is the mouse foot method which takes a long period to yield results. The Fc receptor assay using the ability of viable M. leprae to alter the membrane of the macrophage is well established. It takes only ten days and is inexpensive. In 6 cases of leprosy patients the susceptibility pattern was worked out both with the in vitro Fc receptor assay and the vivo in mouse foot method The results correlated very well leading to the fact that the assay system is reliable. Hence it can be used not only to study the status of a patient, but also to shortlist the number of compounds to be tested on the mouse foot pad as anti-leprosy drug candidates.
Subject(s)
Animals , Drug Evaluation, Preclinical/methods , Fluoresceins/diagnosis , Leprosy/drug therapy , Macrophages/immunology , Mice , Mycobacterium leprae/drug effects , Receptors, Fc/analysisABSTRACT
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.
ABSTRACT
The observation that live Mycobacterium leprae on entry into macrophages from lepromatous leprosy patients reduced the number of EA rosetting macrophages, was extended to macrophages from Swiss white mice also. Further, the fact that dead Mycobacterium leprae do not bring about such a change in macrophages from mice, allowed us to develop this into a bacterial viability testing system. Thus drug treated macrophages in the presence of Mycobacterium leprae showed normal rosetting ability if Mycobacterium leprae are inactivated by the drug, but showed reduced level of rosetting when bacteria were not susceptible to the drug. It was shown that a drug like dapsone, does act on Mycobacterium leprae based on its permeability, quantity available inside the macrophages and inhibition of its action by Para amino benzoic acid. The inactivation of Mycobacterium leprae by sulphone and rifampicin was also proved by the flourescence diacetate method, which showed poorly viable bacteria after exposure to drugs. Thus it has been possible to develop a rapid drug screening method for testing the activity of unknown compound against Mycobacterium leprae.