Correlation of morphology with viability of Mycobacterium leprae

A concept has been developed in the recent years that the evenly stained 'solid' bacilli are living and the 'non-solid' forms are degenerate and dead. This communication presents the findings in experimental mice inoculated with material containing 1 to 10% solid evenly stained M. leprae and also with material containing 0% solid organisms. There was multiplication of the bacilli in both the groups. Quantitatively, the yield also was not significantly different. These fundings do not support the belief that the non-solid bacilli are necessarily dead. The non-solid bacilli were further classified on the basis of their morphology to the following forms:-- (a) short but evenly stained (b) indented (c) beaded (d) dumb-bell shaped (e) coccoid and (f) fragmented. Material without solid bacilli, but containing different proportions of the above types of bacilli also gave similar results, making it diffcult to say which types of morphological forms are non-living. It appears, therefore, that the recognition of the living status of M. leprae by its morphology is highly equivocal and subject to error.