Mouse foot pad growth of M. leprae in relation to bacteriological index.

A retrospective analysis was made of the mouse foot-pad growth of M. leprae from 35 cases of lepromatous leprosy with B.I. ranging from 1.33 to 4.0 (Dharmendra scale). Of these 35 cases, 6 were found to be harbouring dapsone resistant bacilli and 18 cases sensitive bacilli. In 11 of them there was no growth in the control group of animals. The analysis showed that there was no difference in the mean B.I. between those showing no growth and those showing growth in the 1st, 2nd or 3rd harvest. A minimum B.I. around 1.5 is considered adequate for positive foot-pad takes. Another interesting observation made in the study was that the growth rate in the control group foot-pads was consistently higher in mice receiving dapsone resistant bacilli as compared to those inoculated with bacilli, sensitive to the drug.