Bacteriology of leprosy

Leprosy is caused by mycobacterium leprae which is an acid fast bacillus. It's acid fastness if relatively less compared to mycobacterium tuberculosis. Pyridine extractability of acid fastness is a unique feature not found in other pathogenic mycobacteria.

The bacillus is a slightly curved rod that measures 2-8 microns in length and 0.2 to 0.6 microns in breadth. It's ends are usually blunted or rounded. The entire bacillus may

be uniformly stained with carbol fuschin when it is known as "solid form". The bacillus may be stained only at intervals when it is known as "beaded form", or in small fragments when it is known as "fragmented form" or in the form of small granules when

it is known as "granular form". The solid form is viable and the other three are nonviable.