Bacterial infectious complications are the most common cause of morbidity and mortality associated with acute pancreatitis. Most pathogens are common gastrointestinal flora, indicating that the gut is the source of pancreatitis-related infections. However, the route whereby the microorganisms reach distant organs remains speculative. We tested the hypothesis that spread of bacteria occurs via a transperitoneal pathway. Acute interstitial pancreatitis (AIP) was induced in antibiotic (gentamicin, bacithracin, neomycin)-decontaminated rats by intravenous infusion of cerulein. Effects of pancreatic necrosis (PN) were studied in rats that received additional injections into the peritoneal cavity of pancreatic tissue obtained from donor rats. The rats were inoculated with Escherichia coli (O2:KN:H18) resistant to the antibiotics used for decontamination either orally (10(12) microorganisms; experiment I) or intraperitoneally (10(8) microorganisms; experiment II). Moreover, the rat peritoneal cavity wash was inoculated with 10(8) E. coli in vitro (experiment III). In rats with AIP and PN, recovery of the bacteria from liver, spleen, pancreas, lung, and blood following oral inoculation demonstrated that acute pancreatitis promotes bacterial translocation from the gut. The absence of E. coli in these organs following intraperitoneal inoculation showed that the bacteria do not spread from the peritoneal cavity. Rats with PN cleared E. coli from the peritoneal cavity in a shorter period than rats with AIP and controls (5 vs. 7 and 8 days; p < 0.05). The multiplication rate of E. coli in peritoneal cavity wash was lower in rats with PN than in rats with AIP and controls (p < 0.01). We conclude that (1) translocation of E. coli from the gut during cerulein-induced acute pancreatitis occurs via nonperitoneal pathways, (2) the peritoneal cavity acts as a trap for the bacteria rather than a source of bacterial seeding, and (3) PN impairs survival of E. coli in the peritoneal cavity via inhibition of the bacterial multiplication in this model.