Cecocolitis in immunodeficient mice associated with an enteroinvasive lactose negative E. coli
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K S Waggie1, C T Hansen, T D Moore
1Comparative Pathology Section, National Institutes of Health, Bethesda, MD 20892.
Abstract:
Infection with an atypical (lactose-negative) E. coli was associated with increased mortality rates in a colony of triple immune deficient N:NIH(S) III mice. Affected mice were lethargic and exhibited perianal fecal staining. Slight-to-moderate thickening of the wall of the cecum and colon was found on necropsy examination. Microscopic examination revealed segmental hyperplasia of the cecal and colonic mucosa with clusters of gram negative bacteria on the surface and within the cytoplasm of mucosal epithelial cells. Scattered foci of epithelial invasion and hyperplasia were observed in the colons of C57B1/6N-nunu mice after per os inoculation with the atypical E. coli. Immunocompetant mice housed in the same room as the N:NIH(S) III's remained healthy and exhibited no gross or microscopic lesions in spite of infection.
Insights
Atypical E. coli infection significantly increased mortality in immune deficient mice, causing lethargy and gut inflammation. Healthy mice remained unaffected, highlighting the role of immune status in E. coli susceptibility.
Area of Science:
- Microbiology
- Immunology
- Veterinary Pathology
Background:
- Atypical (lactose-negative) Escherichia coli strains can cause disease.
- Immune deficiency can predispose animal models to opportunistic infections.
Purpose of the Study:
- To investigate the pathogenicity of an atypical E. coli strain in immunocompromised mice.
- To characterize the clinical and pathological findings associated with this infection.
Main Methods:
- Infection of triple immune deficient N:NIH(S) III mice with atypical E. coli.
- Clinical observation, necropsy, and histopathological examination of affected tissues.
- Comparison with immunocompetent mice and C57B1/6N-nunu mice.
Main Results:
- Increased mortality rates observed in N:NIH(S) III mice.
- Clinical signs included lethargy and fecal staining.
- Histopathology revealed cecal and colonic mucosal hyperplasia with bacterial invasion of epithelial cells.
- Immunocompetent mice showed no signs of disease.
Conclusions:
- Atypical E. coli poses a significant mortality risk to severely immunocompromised mice.
- The pathogen invades and causes hyperplasia of the intestinal mucosa.
- Immune status is critical in determining susceptibility to this E. coli infection.