The Journal of Medical Microbiology, Vol 25, Issue 1 13-15, Copyright © 1988 by Society for General Microbiology
Rifampicin-resistant strains of Mycobacterium leprae may have reduced virulence
R. D. McDermott-Lancaster and G. R. Hilson
Department of Medical Microbiology, St. George's Hospital Medical School, London.
A strain of Mycobacterium leprae resistant to rifampicin (RMP) failed to
infect normal mice when injected into the foot pads (FP) at a dose of 10 or
100 bacilli/FP, although it could be maintained by serial passage in mice
by the use of inocula of 10(4) bacilli/FP; normal mice can be infected by
RMP-sensitive M. leprae at a dose of 10 bacilli/FP. By contrast, nude
(athymic) mice could be infected with an inoculum of 10 bacilli/FP of the
RMP-resistant strain. It is suggested that the strain concerned possessed
reduced virulence for normal mice, and the implications of this for the
probability of occurrence of human disease caused by RMP-resistant strains
of M. leprae are discussed.
