BACKGROUND: Spontaneous bacterial peritonitis (SBP) is a severe complication of cirrhotic patients associated with a high mortality. AIM: To develop an available experimental model of induced bacterial peritonitis in cirrhosis. MATERIAL AND METHODS: Sprague-Dawley rats with carbon-tetrachloride- induced cirrhosis with (N = 22) or without (N = 101) ascites were randomized to receive an intraperitoneal administration of different concentrations of Escherichia coli (E. coli) diluted in 1 mL of sterile water in ascitic rats and in different volumes in nonascitic rats. A subgroup of nonascitic animals received ceftriaxone 4 h after E. coli inoculation. Mortality of rats was evaluated 24 h after bacterial inoculation. RESULTS: None of the rats receiving sterile water alone and only one infected with 107 cfu of E. coli died. Ascitic rats showed a lower mortality rate than nonascitic rats infected with 108 or 109 cfu of E. coli (P < 0.05). Mortality was higher with 109 cfu than with 108 cfu of E. coli in ascitic (P NS) and nonascitic (P < 0.01) rats. A trend was noted to ward higher mortality in nonascitic rats inoculated with 108 cfu with increasing water volumes. A marked peritoneal polymorphonuclear cell response was observed 4 h after E. coli injection in both ascitic and nonascitic rats. Antibiotic therapy significantly reduced the mortality rate of rats infected with 108 cfu (P < 0.01). CONCLUSIONS: This experimental model of induced bacterial peritonitis in cirrhosis with or without ascites may represent a useful tool for the study of pathogenic events postinfection and for the design of new therapeutic strategies to treat patients with SBP. © 2007 by Am. Coll. of Gastroenterology.