A peritonitis model with low mortality and persisting intra-abdominal abscesses

Area of Science:

• Surgical Research
• Infectious Diseases
• Animal Models

Background:

• Intra-abdominal abscesses can cause persistent infection post-surgery for secondary peritonitis.
• Effective therapies require a model with low mortality and reproducible abscess formation.
• Studying the local inflammatory response is key to developing new treatments.

Purpose of the Study:

• To establish a reliable animal model for intra-abdominal abscesses.
• To investigate the inflammatory response in a model of generalized peritonitis.
• To facilitate the development of therapies for post-surgical infections.

Main Methods:

• Male Wistar rats received intraperitoneal injections of rat feces, E. coli (10^4-10^8 cfu/ml), and B. fragilis (10^4 cfu/ml).
• Surgical debridement was performed after one hour, followed by sample collection (blood, abdominal fluid) at various time points.
• Animals were euthanized after five days for abscess assessment.

Main Results:

• Mortality varied with E. coli dose (90% at highest, 30% at lowest).
• Lower E. coli doses (10^4-10^6 cfu/ml) resulted in abscesses in most survivors and frequent bacteremia.
• Peritoneal fluid showed significant cytokine concentrations (TNF-alpha, IL-6, IL-1beta, IL-10) at 24 hours, decreasing by 72 hours.

Conclusions:

• The developed rat model is suitable for studying intra-abdominal abscess formation mechanisms.
• This model aids in evaluating preventive strategies for infections after generalized peritonitis surgery.
• The model effectively combines abscess induction with the study of local inflammation.