Rattus norvegicus: not a model for Aeromonas-associated gastroenteritis in man

Area of Science:

• Microbiology
• Infectious Diseases
• Animal Models

Background:

• Investigating Aeromonas pathogenic mechanisms is hindered by the absence of a suitable animal model for Aeromonas-associated diarrhea.
• A previous report suggested clindamycin-pretreated rats could serve as a model for Aeromonas enteritis.

Purpose of the Study:

• To investigate the validity of the clindamycin-treated rat model for studying Aeromonas enteropathogenicity.
• To determine if Aeromonas species can colonize and cause histological damage in clindamycin-pretreated rats.

Main Methods:

• Six Aeromonas strains were inoculated intragastrically into clindamycin-pretreated rats.
• Bacterial recovery from stools and intestinal histology were assessed post-inoculation.
• Comparison was made with Pseudomonas aeruginosa colonization in the same model.

Main Results:

• Aeromonas strains showed limited colonization (≤2 days) and did not cause significant histological damage.
• Pseudomonas aeruginosa, however, demonstrated long-term colonization (>12 days) and histological damage.
• Bacterial destruction in vivo appeared to be mediated by immune mechanisms, not bacterial sensitivity.

Conclusions:

• The clindamycin-treated rat model is not suitable for investigating the enteropathogenicity of Aeromonas species.
• The model's inability to support Aeromonas colonization and induce disease contrasts with its efficacy for Pseudomonas aeruginosa.
• Further research is needed to understand the discrepancy with previous findings and explore alternative models.