The simultaneous inoculation of Mycobacterium leprae and M. intracellulare into nude mice: development of cutaneous leproma and accelleration of foot pad swelling.

Organisms of the non-pathogenic Mycobacterium intracellulare serotype 19 Darden enhanced the pathogenicity of M. leprae when inoculated together into the foot pads of nude mice. This supporting effect could be demonstrated by an accelleration of foot pad swelling, beginning 4 months after inoculation and by the development of cutaneous leproma on dorsal and lateral body sites within 6 months after inoculation. These leproma increased in number and size during the 9 months they were under observation and demonstrated micromorphological characteristics similar to those of human leprosy.

Presence of "difficult to isolate" mycobacteria in armadillos.

Contrary to the findings with armadillos from Louisiana and Texas, armadillos from Florida are free of natural leprosy-like infection. Examination of ear clip, nasal, blood buffy coat, liver and spleen of inoculated armadillos from Florida did not reveal the presence of any acid fast bacteria. However, using massive inocula, 6 out of 77 armadillo tissues were found to contain very negligible proportions of cultivable mycobacteria. The significance of these isolates in relation to M. leprae and also to leprosy research is discussed.