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Microbial synergy in experimental intra-abdominal abscess
Abstract:
Intra-abdominal sepsis was studied in Wistar rats by using four microbial species: Escherichia coli, enterococci, Bacteroides fragilis, and Fusobacterium varium. These organisms were implanted into the peritoneal cavity singly and in all possible dual combinations. Results were evaluated by mortality rates and the incidence of intra-abdominal abscesses on autopsy following sacrifice after 7 days. Mortality was restricted to recipients of E. coli, thus implicating coliforms in the acute lethality associated with this experimental model. Intra-abdominal abscesses were produced in 61 of 95 (94%) animals that received the combination of an anaerobe and a facultative organism. Abscesses failed to form with any single strain or with E. coli plus enterococci, and they were detected in one 1 of 19 animals receiving B. fragilis plus F. varium. These results suggest that intra-abdominal abscess formation is related to synergy between anaerobes and facultative bacteria.
Insights
Intra-abdominal sepsis in rats revealed that coliforms like Escherichia coli cause acute mortality. Abscess formation requires synergy between anaerobic and facultative bacteria, not single strains.
Area of Science:
- Microbiology and Immunology
- Surgical Infection Models
- Bacterial Pathogenesis
Background:
- Intra-abdominal sepsis is a significant clinical challenge.
- Understanding polymicrobial infections is crucial for effective treatment.
- Previous models have limitations in replicating complex infections.
Purpose of the Study:
- To investigate the role of specific microbial species in intra-abdominal sepsis.
- To determine the contribution of individual and combined bacterial inocula to mortality and abscess formation.
- To elucidate the synergistic interactions between anaerobic and facultative bacteria in abscess development.
Main Methods:
- Wistar rats were inoculated with single or dual combinations of four microbial species: Escherichia coli, enterococci, Bacteroides fragilis, and Fusobacterium varium.
- Inoculations were administered into the peritoneal cavity.
- Outcomes assessed included mortality rates and the incidence of intra-abdominal abscesses at 7 days post-inoculation.
Main Results:
- Mortality was exclusively observed in rats receiving Escherichia coli, highlighting the acute lethality of coliforms.
- Intra-abdominal abscesses developed in 94% of animals receiving a combination of an anaerobe and a facultative organism.
- Abscess formation was notably absent with single strains or the combination of E. coli and enterococci, and low with two anaerobes (B. fragilis and F. varium).
Conclusions:
- Synergistic interactions between anaerobic and facultative bacteria are critical for intra-abdominal abscess formation.
- Coliforms, specifically E. coli, play a significant role in the acute mortality associated with this sepsis model.
- Understanding these microbial dynamics is essential for developing targeted therapeutic strategies against intra-abdominal infections.