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Differences in susceptibility to peroral inoculation with Bacillus piliformis spores in rats and mice
1Central Institute for Experimental Animals, Kanagawa, Japan.
Abstract:
The median liver lesion producing doses of peroral inoculation with the spores of Tyzzer's organism RJ strain were 10(4. 3) in rats and 10(2. 7) in rats receiving prednisolone treatment for the provocation of Tyzzer's disease. In contrast to rats, liver lesions were detected in few mice inoculated perorally with 10(7) spores. In mice inoculated perorally with 10(7) spores, excretion of infective spores in the feces was detected only on day 1 postinoculation. On the other hand, no difference in susceptibility between rats and mice was detected upon intravenous inoculation with vegetative cells of the RJ strain. These results suggest that germination of the spores in the intestinal tract causes the difference in the susceptibility in rats and mice.
Insights
Rats are more susceptible to Tyzzer
Area of Science:
- Microbiology
- Immunology
- Veterinary Medicine
Background:
- Tyzzer's disease, caused by Clostridium piliforme (formerly Bacillus piliformis), affects various animal species.
- The susceptibility to Tyzzer's disease can vary significantly between species and routes of infection.
Purpose of the Study:
- To investigate the difference in susceptibility to Tyzzer's organism (RJ strain) between rats and mice via different inoculation routes.
- To determine the role of spore germination in the intestinal tract in disease pathogenesis.
Main Methods:
- Peroral and intravenous inoculation of rats and mice with Tyzzer's organism (RJ strain).
- Administration of prednisolone to rats to provoke Tyzzer's disease.
- Monitoring for liver lesions and detection of spore excretion in feces.
Main Results:
- Rats showed higher susceptibility to peroral inoculation with Tyzzer's spores, with median effective doses (MEDs) of 10(4.3) and 10(2.7) in untreated and prednisolone-treated rats, respectively.
- Mice exhibited resistance to peroral inoculation, with liver lesions detected only in a few individuals even at high doses (10(7) spores).
- No difference in susceptibility was observed between rats and mice when inoculated intravenously with vegetative cells, suggesting intestinal spore germination is key.
Conclusions:
- Intestinal spore germination of Tyzzer's organism is a critical factor determining differential susceptibility between rats and mice.
- Rats are significantly more susceptible to Tyzzer's disease via the oral route, especially when immune-compromised.
- The findings highlight the importance of the gastrointestinal tract in the pathogenesis of Tyzzer's disease.