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Colonization of streptomycin-treated mice by Aeromonas species
K Sanderson1, F M Ghazali, S M Kirov
1Department of Pathology, University of Tasmania, Australia.
Abstract:
Streptomycin-treated adult mice were investigated as a possible model for studying the enteropathogenicity of Aeromonas species. C57BL mice pre-treated with streptomycin (5.0 g/L drinking water, 48 hours) received a single intragastric dose (10(10) bacteria /10.5 mL) of one of six well-characterized, toxin-producing, human diarrhoeal isolates of A. veronii biovar sobria (n = 3) or A. hydrophila (n = 3). Their faeces were examined for Aeromonas for 10 days post-challenge. All strains colonized the antibiotic-treated mice. Colonization did not occur in mice which did not receive streptomycin. Strains of A. hydrophila were recovered in greater numbers than strains of A. veronii biovar sobria, and colonized ( > or = 10(3) cfu/g of faeces) a greater proportion of mice at day 10. Strains of the latter species, however, were more adherent in cell line assays used as models of intestinal adhesion. A. hydrophila strains localized in the large intestine and appeared not to be cell associated. This study, therefore, points to species-related differences in intestinal colonization mechanisms. The streptomycin-treated adult mouse model may prove useful for further investigation of some of these mechanisms. Diarrhoeal symptoms were, however, not produced in this model.
Insights
Streptomycin-treated mice can model Aeromonas enteropathogenicity, with A. hydrophila colonizing better than A. veronii. This mouse model aids studying bacterial gut colonization mechanisms.
Area of Science:
- Microbiology
- Infectious Diseases
- Animal Models
Background:
- Aeromonas species are significant enteropathogens.
- Understanding Aeromonas intestinal colonization mechanisms is crucial for developing effective treatments.
- Existing models may not fully replicate human infection dynamics.
Purpose of the Study:
- To evaluate streptomycin-treated adult mice as a model for Aeromonas enteropathogenicity.
- To investigate species-specific differences in Aeromonas intestinal colonization.
- To explore mechanisms of Aeromonas gut adhesion and localization.
Main Methods:
- Adult C57BL mice were pre-treated with streptomycin in drinking water.
- Mice received intragastric doses of human diarrheal isolates of Aeromonas veronii or Aeromonas hydrophila.
- Fecal samples were analyzed for Aeromonas recovery over 10 days post-challenge.
- Cell line assays were used to assess bacterial adhesion.
Main Results:
- All tested Aeromonas strains colonized streptomycin-treated mice, but not untreated mice.
- Aeromonas hydrophila strains showed higher recovery numbers and colonized a greater proportion of mice at day 10 compared to Aeromonas veronii.
- Aeromonas veronii strains exhibited greater adherence in cell line assays.
- Aeromonas hydrophila localized in the large intestine and was not cell-associated.
Conclusions:
- Streptomycin-treated mice serve as a viable model for studying Aeromonas colonization.
- Species-specific differences exist in Aeromonas intestinal colonization mechanisms, involving adherence and localization.
- The model shows potential for further investigation into these mechanisms, though it did not induce diarrhea.