M. lepraemurium

This is an organism found in rats in a disease somewhat

resembling leprosy. It can be passed on experimentally to

other animals of the same species.

Non-pathogenic Species

M. smegmatis

The smegma bacillus is an acid-fast bacillus found in the

smegma secretion around the genital and anal parts of human

beings and in some animals such as dogs. It can also be found

in other parts of the body, e.g. in the ear. The bacillus may be

found in the urine, but if the urine is carefully collected after

cleansing the external parts it can usually be avoided.

It is generally shorter and thicker than the tubercle

bacillus, and many strains of the smegma bacillus are

decolorized by alcohol, which distinguishes them from the

tubercle bacillus. They grow rapidly in culture.

M. butyricum

The butter bacillus. These bacilli may be found in grass,

water, butter, milk, manure, etc. They grow rapidly in

culture.