Rifampin and Cefazolin as Prophylactic Agents

We investigated rifampin and cefazolin sodium as prophylactic agents in a dog model of vascular graft infection. A 1-cm segment of 3-mm-diameter polytetrafluoroethylene (Gore-tex) graft was sewn into the right carotid artery of each dog, and prior to closure, 10(3) Staphylococcus organisms sensitive to both cefazolin and rifampin were injected over the graft. The dogs were killed five days after surgery and the grafts cultured. Infection occurred in 100% of controls, 58% of cefazolin-pretreated dogs, and 17% of rifampin-pretreated dogs. Mean blood levels of antibiotics were assayed as follows: cefazolin, 50.1 micrograms/mL; rifampin, 2.9 micrograms/mL. Both were well above the minimal inhibitory concentration. Thus, rifampin proved to be more effective than cefazolin in this animal model.