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A preliminary study on the pathogenicity of Bacillus licheniformis bacteria in immunodepressed mice
J S Agerholm1, N E Jensen, S B Giese
1Department of Pathology and Epidemiology, Danish Veterinary Laboratory, Copenhagen, Denmark.
Abstract:
The pathogenicity of 13 strains of Bacillus licheniformis was studied in immunodepressed mice. The strains had been isolated from cases of bovine abortions (n = 5), bovine feedstuffs (n = 3), soil (n = 1), and grain products (n = 2). The origin of two strains was unknown. Groups of 10 mice were inoculated intravenously with B. licheniformis bacteria at doses from < 10(6) to 10(10) colony-forming units. Following 7 days of infection, the animals were euthanized and examined bacteriologically, histologically, and immunohistochemically using a PAP technique based on primary polyclonal rabbit anti-B. licheniformis antibodies. B. licheniformis bacteria were reisolated from the liver, spleen or kidneys of mice in all groups. Inflammatory lesions were present in mice of all immunodepressed groups, but only brain and pulmonic lesions were definitely attributed to B. licheniformis infection, as strong immunostaining was found within these lesions. It is concluded that all strains of B. licheniformis examined were pathogenic for immunodepressed mice, and that spontaneous infections may be established by bacterial strains to which susceptible individuals are accidentally exposed.
Insights
All 13 Bacillus licheniformis strains tested were pathogenic in immunodepressed mice, causing infections originating from various sources. This highlights the risk of spontaneous infections from accidental exposure to these bacteria.
Area of Science:
- Veterinary Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Bacillus licheniformis is a bacterium found in various environments, including animal feed and products.
- Its pathogenicity, particularly in immunocompromised individuals or animals, requires further investigation.
Purpose of the Study:
- To assess the pathogenicity of diverse Bacillus licheniformis strains in an animal model.
- To determine the potential for B. licheniformis to cause systemic infections.
Main Methods:
- Utilized immunodepressed mice model for pathogenicity testing.
- Administered intravenous inoculations of B. licheniformis strains at varying doses.
- Conducted bacteriological, histological, and immunohistochemical analyses post-infection.
Main Results:
- Bacillus licheniformis was reisolated from the liver, spleen, and kidneys of infected mice across all groups.
- Inflammatory lesions were observed in all immunodepressed groups.
- Brain and pulmonic lesions showed strong immunostaining, confirming B. licheniformis as the causative agent.
Conclusions:
- All examined B. licheniformis strains demonstrated pathogenicity in immunodepressed mice.
- Spontaneous infections can occur through accidental exposure to susceptible individuals.
- The study underscores the importance of monitoring B. licheniformis in animal health contexts.