Standardized intraabdominal abscess formation with generalized sepsis: pathophysiology in the rat

Gelatine capsules containing Escherichia coli and Bacteroides fragilis in a standardized mixture with rat colonic content and barium sulfate were implanted intraabdominally into rats. Capsules of 0.75 g gave approximately 50% mortality whereas 0.35 and 1.10 g caused no or 100% mortality, respectively. In subsequent experiments, using the 0.75 g capsule, all animals became ill with signs of tachypnea, piloerection, low physical activity and hypersecretion of saliva 6-8 h after the implantation. The animals reduced their water and food intake substantially and the body weight decreased. A significant reduction in blood pressure, glucose and leukocyte and platelet counts was found 12 h after challenge. Blood cultures obtained at 12, 24, 48 and 60 h all grew E. coli but none B. fragilis. Succumbed animals revealed diffuse peritonitis with growth of E. coli and B. fragilis at autopsy, whereas surviving animals showed abscess formation at investigation on day 8 after challenge. It was concluded that the model closely resembled intraabdominal abscess formation with sepsis in man.