EVALUATION OF THERAPY WITH HYPERBARIC-OXYGEN FOR EXPERIMENTAL-INFECTION WITH CLOSTRIDIUM-PERFRINGENS

The effects of inoculum size and treatment delays on the efficacy of h yperbaric oxygen (HBO) were evaluated in a m urine model of Clostridiu m perfringens myositis in which the infection was treated with an HBO regimen identical to that used for humans. The efficacies of treatment with penicillin, metronidazole, or clindamycin-alone or in combinatio n with HBO-were also assessed. Survival was inversely related to the s ize of the bacterial inoculum used for challenge, and delays in treatm ent markedly reduced the efficacies of all single and combination regi mens. When animals were challenged with > 10(8) colony-forming units, survival was significantly higher among those treated with clindamycin or metronidazole than among those treated with penicillin. HBO alone did not improve survival at any inoculum tested. However, when adminis tered early, HBO plus metronidazole or penicillin demonstrated signifi cant additive efficacies in animals challenged with greater-than-or-eq ual-to 10(9) organisms. Clindamycin was more effective at the higher i nocula than penicillin, metronidazole, or HBO, and its superior effica cy was not further enhanced by adjunctive therapy with HBO.