OBJECTIVE
To develop a standardised and reproducible model of intra-abdominal infection and abscess formation in rats.
DESIGN
Experimental study.
SETTING
University hospital, The Netherlands.
SUBJECTS
36 adult male Wistar rats.
INTERVENTIONS
In 32 rats, peritonitis was produced using two different concentrations of Escherichia coli (E. coli) and Bacteroides fragilis (B. fragilis) incorporated in fibrin clots (E. coii 1 x 10(5) colony forming units (CFU)/ml or 1 x 10(8) CFU/ml, B. fragilis: 1 x 10(8) CFU/ml). Four rats with fibrin clots without bacteria served as uninfected controls.
MAIN OUTCOME MEASUREMENTS
Macroscopy and bacterial counts in peritoneal fluid, blood, and fibrin clots after 24 hours, 4 days, 7 days, and 4 weeks.
RESULTS
Macroscopically, there were signs of intra-abdominal infection and abscesses. With the higher starting concentration of E. coli, macroscopic signs were more pronounced and in nearly all rats bacterial counts in peritoneal fluid and fibrin clots showed persistently high numbers of E. coli and B. fragilis for at least 7 days (E. coli = 2 x 10(3) to 1 x 10(6) CFU/ml and 5 x 10(7) to 9 x 10(8) CFU/clot; B. fragilis = 1 x 10(3) to 1 x 10(6) CFU/ml and 5 x 10(7) to 6 x 10(8) CFU/clot).
CONCLUSION
This standardised and reproducible model of intra-abdominal infection and abscess formation seems well suited for further use and development in experiments on the pathophysiology of intra-abdominal infection and abscesses.