A decisive period in cefoxitin prophylaxis of experimental synergistic wound infection produced by Bacteroides fragilis and Escherichia coli.

In an experimental model of synergistic infection produced by Escherichia coli and Bacteroides fragilis, a single injection of cefoxitin 1 h before inoculation of the bacteria was able to prevent both death and local wound infection (P less than 0.05). When cefoxitin was administered 1 h after the bacterial inoculum, death of the animals, but not the wound infection, was prevented (P greater than 0.1). Cefazolin, active against the E. coli only, could prevent death, but had no significant effect (P greater than 0.1) on the prevention of wound sepsis.