Comparison of cefoxitin, cefotetan and the combination of ampicillin with sulbactam in the therapy of polymicrobial infection in mice.

The comparative efficacies of cefoxitin, cefotetan and the combination of ampicillin with sulbactam were investigated in mixed aerobic and anaerobic infections of mice. Treatment was administered by intramuscular injection for 10 days and was started 1 h before infection. After intraperitoneal infection with Escherichia coli, Bacteroides fragilis, and one other member of the B. fragilis group (either Bacteroides thetaiotaomicron, Bacteroides ovatus or Bacteroides distasonis), 41 of 90 (46%) control mice died and all survivors developed polymicrobial abscesses. Cephalosporin therapy reduced mortaligy 13% with cefoxitin, 3% with cefotetan, and 23% with ampicillin plus sulbactam; 14%, 10% and 14% of surviving animals, respectively developed abscesses. Each of the treatment regimens significantly reduced the number of all organisms in abscesses, independent of their activity in vitro. However, the reduction in the number of E. coli by ampicillin plus sulbactam was less marked (P < 0.001) than that achieved by cefoxitin (P < 0.05) or cefotetan. These data show that in vivo efficiencies of cefoxitin and cefotetan, are independent of their in vitro potencies in the early management of polymicrobial infections in mice.