ANTIBACTERIAL ACTIVITY, ANTIBIOTIC RETENTION, AND INFECTION-RESISTANCE OF A RIFAMPIN-IMPREGNATED GELATIN-SEALED DACRON GRAFT

Purpose: A gelatin-sealed porous Dacron graft impregnated with rifampi n was evaluated in a two-part study of its use in preventing prostheti c infection. Methods: The graft was impregnated by soaking it for 15 m inutes in rifampin (1 mg/ml). In part 1 its antibacterial activity and rifampin retention over time were determined. Infrarenal aortic repla cement was performed in pigs, and the rifampin concentration of the gr aft, serum, and perigraft space was assayed up to 96 hours after surge ry. In part 2, infection resistance was tested in pigs in which the re troperitoneum was contaminated with Staphylococcus aureus after graft replacement. The postoperative infection rate was compared in three gr oups: pigs given gelatin-sealed grafts without rifampin (controls), pi gs receiving nonimpregnated grafts and intravenous rifampin (15 mg/kg) for 3 days after surgery, and those given the rifampin grafts. Result s: Rifampin was present in the grafts for up to 72 hours after surgery and in the perigraft fluid for 24 hours but was never detected in the serum. The grafts had inhibitory activity in vitro against S. auresus and the biofilm phase of Staphylococcus epidermidis for up to 3 days and against Escherichia coli for 2 days. Pigs given intravenous rifamp in had a significantly lower infection rate than had control pigs (7/1 2 vs 13/13; p = 0.02); those receiving the rifampin graft had a lower rate (2/13) than had either the control pigs (p < 0.001) or those give n intravenous rifampin (p < 0.04). Conclusions: This simple method of graft impregnation resulted in antibiotic retention for 3 days and app eared to be superior to intravenous antibiotic administration in preve nting perioperative graft infection.