Activity of penicillin or ticarcillin in combination with clavulanic acid in the treatment of experimental intra-abdominal abscess.

The combination of clavulanic acid (CA) with penicillin or ticarcillin was evaluated in a rat intra-abdominal abscess model. Gelatin capsules filled with a mixture of Bacteroides fragilis and Escherichia coli were implanted intraperitoneally in male Wistar rats. Four different groups of animals with appropriate controls were treated with penicillin or ticarcillin alone or in combination with CA. The treatment was started either immediately or delayed for 48 h after peritoneal inoculation. The therapeutic regimen was given for ten days at 8-hourly intervals. The mortality rate decreased to almost one-half when antibiotic therapy was started within 6 h. Seventy-nine to 89% of animals were cured when treated with ticarcillin in combination with CA showing that ticarcillin + CA was the most effective regimen of those tested in the treatment of experimental intra-abdominal abscess of rats caused by Bact. fragilis and E. coli.