CORYNEBACTERIAL PSEUDOTUBERCULOSIS IN MICE : I. COMPARATIVE SUSCEPTIBILITY OF MOUSE STRAINS TO EXPERIMENTAL INFECTION WITH CORYNEBACTERIUM KUTSCHERI

The susceptibility of mice to experimental infection with Corynebacterium kutscheri was studied by comparing the host response to this organism of mice obtained from 31 different colonies, representing 15 different genetic types. A standardized infective dose, administered intravenously, made it possible to separate the animals into two sharply differentiated groups. All the animals of the following colonies died: Swiss Lynch, Swiss R/J, A/Jax, Princeton, RFVL, and CF(1) (SPF). All the animals of the following colonies survived: CFW, ICR, Balb/C, BSVS, BRVR, RIII, YBR/He, DBA/2 (from 3 different colonies), and C57B1/6 (from 12 different colonies). The two highly inbred strains, Swiss Lynch and C57Bl/6, were selected as prototypes of susceptible and resistant animals respectively, for more detailed studies. Following injection of an infective dose of 0.2 x 10(–4) ml of culture of C. kutscheri, all Swiss Lynch animals died within 3 to 11 days (the majority within 4 to 7 days); whereas all C57Bl/6 animals survived. The outcome of the infection in each strain was independent of age and sex of the animals. In Swiss Lynch animals, the corynebacteria multiplied rapidly in lungs, liver, kidneys, and to some extent in the spleen. In C57Bl/6 mice, there was no increase of the corynebacterial population in the lungs, liver, or spleen, but multiplication occurred in the kidneys during the early phase of the infectious process with resultant abscess formation. However, the renal infection soon subsided leaving no residual pathology. C. kutscheri could not be recovered from any organs of C57Bl/6 mice sacrificed 16 days after infection. Homogenates of organs from Swiss Lynch mice obtained while the infection was progressing contained only typical C. kutscheri. In contrast, the lungs and livers of similarly infected C57Bl/6 animals occasionally yielded large numbers of small translucent colonies distinctly different from those of typical corynebacteria. The use of mouse strains differing markedly in response to experimental infection with C. kutscheri is presented as a biologic model lending itself to further studies concerning factors which condition resistance to corynebacterial pseudotuberculosis, a disease of practical importance for investigators conducting experiments with murine species.