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Oral challenge with Aeromonas in protein-malnourished mice
G Pazzaglia1, I Winoto, G Jennings
1U.S. Naval Medical Research Unit No. 2, Jakarta, Indonesia.
Abstract:
The lack of an animal model for Aeromonas-associated diarrhoea has hindered progress toward understanding the pathogenesis of this potentially important enteric infection. Protein-malnourished mice were challenged orally with Aeromonas strains to determine if diminished levels of resistance would allow the induction of a diarrhoeal response. The 15 Aeromonas spp. faecal isolates used for challenge included 7 A. caviae, 4 A. hydrophila, 1 A. sobria bv. sobria, and 1 A. sobria bv. veronii from patients with diarrhoea, and 2 A. caviae from healthy volunteers. All had at least 1 known virulence marker, with the exception of 1 strain. Mice on the protein deficient diet had lost an average of 23% of their initial body weight at the time of challenge. Although mice consumed 10(8) cfu per day for a minimum of 4 days, none became ill due to Aeromonas spp. ingestion. Aeromonas spp. were isolated from 75% of faecal cultures obtained 7 days after initial challenge, indicating bowel colonization had occurred.
Insights
Protein-malnourished mice did not develop Aeromonas-associated diarrhea, despite successful gut colonization. This study highlights the need for a suitable animal model to understand Aeromonas pathogenesis and enteric infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Animal Models
Background:
- Aeromonas-associated diarrhea lacks a suitable animal model, hindering pathogenesis research.
- Aeromonas species are implicated in enteric infections, but their mechanisms remain unclear.
Purpose of the Study:
- To establish if protein-malnourished mice could serve as an animal model for Aeromonas-associated diarrhea.
- To investigate the potential for Aeromonas species to induce diarrheal disease in a compromised host.
Main Methods:
- Oral challenge of protein-malnourished mice with various Aeromonas species isolated from human cases and healthy individuals.
- Monitoring for clinical signs of illness and assessing bacterial colonization through fecal cultures.
Main Results:
- Despite consuming high doses of Aeromonas (10^8 cfu/day for at least 4 days), no mice exhibited diarrhea or became ill.
- Aeromonas species successfully colonized the gastrointestinal tract, with 75% of fecal cultures positive 7 days post-challenge.
Conclusions:
- Protein-malnourished mice do not develop Aeromonas-associated diarrhea, indicating this model is unsuitable for studying this specific infection.
- Further research is needed to develop an appropriate animal model to elucidate the pathogenesis of Aeromonas-induced enteric infections.