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Intra-abdominal abscess formation in mice: quantitative studies on bacteria and abscess-potentiating agents
Abstract:
A model of intra-abdominal (IA) abscess formation has been developed in mice. Intraperitoneal (i.p.) injection of a mixture of a potentiating agent (autoclaved colonic and caecal contents (ACC), 0.2 mg dry wt/mouse or sterile bran, 1 mg dry wt/mouse), Escherichia coli (1 X 10(6) colony forming units (cfu)/mouse) and Bacteroides fragilis (5 X 10(8) cfu/mouse) induced abscesses in 98% of mice inoculated. The abscesses persisted for at least 4 weeks in 60% of inoculated animals, and for 10 weeks in 36%. From 1 to 5 abscesses per mouse were found. Abscess formation was quantified by weighing the dissected abscesses and by culturing bacteria from them. Histologically, the abscesses were characterized by a central region of polymorphonuclear leucocytes, often with a thin mononuclear phagocyte infiltrate surrounding it, and an outer wall of vascularized connective tissue. Fluorescent antibody studies demonstrated that antigens from both bacterial species were distributed throughout the abscess. At the concentrations used, neither ACC nor sterile bran induced formation in the absence of viable bacteria.
Insights
This study developed a mouse model for intra-abdominal abscesses using specific bacteria and potentiating agents. The model successfully induced persistent abscesses, aiding in the study of abdominal infection.
Area of Science:
- Microbiology
- Immunology
- Animal Models
Background:
- Intra-abdominal abscesses are complex infections requiring effective experimental models.
- Understanding the pathogenesis of abscess formation is crucial for developing targeted therapies.
Purpose of the Study:
- To establish and characterize a reproducible mouse model for intra-abdominal abscess formation.
- To investigate the role of specific bacterial species and potentiating agents in abscess development.
Main Methods:
- Intraperitoneal injection of a mixture of Escherichia coli, Bacteroides fragilis, and potentiating agents (autoclaved colonic and caecal contents or sterile bran) in mice.
- Quantification of abscesses by weight and bacterial culture.
- Histological and fluorescent antibody analysis of abscess tissues.
Main Results:
- A high incidence (98%) of abscess formation was achieved using the established model.
- Abscesses demonstrated persistence for up to 10 weeks in a significant proportion of mice.
- Histological examination revealed characteristic inflammatory cell infiltration and connective tissue encapsulation.
Conclusions:
- The developed mouse model effectively replicates intra-abdominal abscess formation.
- This model provides a valuable tool for studying abscess pathogenesis and evaluating potential treatments.