Comparative studies on susceptibility of the mouse (Mus musculus) and the vole (Microtus arvalis) to Listeria monocytogenes and Erysipelothrix rhusiopathiae.

The susceptibility of mice and voles to intraperitoneal and subcutan injection of virulent strains has been tested comparatively on 261 mice and 120 voles. Using various germ-doses, 50 per cent lethality has been established. Listeria monocytogenes serovar 1/2a killed mice in doses of 120,000 and 1.5 X 10(6) germs when injected intraperitoneally and subcutaneously and voles in doses of 1800 and 12,000 germs, respectively. Thus voles proved 100 to 120 times more susceptible than mice. Erysipelothrix rhusiopathiae killed mice injected both intraperitoneally or subcutaneously in minimal doses, such as 25 germs, but voles survived the infection with 1 to 5 million germs. This indicates that voles are resistant to E. rhusiopathiae, but more susceptible to L. monocytogenes than mice. In contrast, both these rodent species proved susceptible to the obligate pathogenic Francisella tularensis and invariably succumbed to septicaemia when injected with a few of these bacteria.