Interaction between vascular prostheses and rifampicin in the prevention of the grafts infection. An experimental study.

Infections caused by synthetic prostheses are relatively rare (1.5-6%) but serious complication in vascular surgery. There is no doubt that during and immediately after surgery bacterial contamination may occur. An in vitro study was carried out in the Vascutek laboratories, which revealed a high affinity between prostheses in Dacron gel and Rifampicin. This affinity, the result of an ionic bond, was demonstrated by the fact that after 5 days Rifampicin was still present on the prostheses. Encouraged by this result, an experimental study was carried out in sheep. Five sheep were operated on making a prosthetic graft in both of the common carotid arteries: on one side a Gelseal Dacron prosthesis was implanted after being soaked for 15 minutes in a solution containing 1 mg/ml Rifampicin. A Knitted Dacron prosthesis was implanted in the contralateral carotid artery, again after pretreatment with Rifampicin. Explants were made after 2, 24, 48, 72 and 96 hours, and the concentration of Rifampicin on the prostheses was assessed on the basis of the diameter of the inhibition area on Staphylococcus aureus cultures. The results showed that the Gelseal Dacron prostheses maintained Rifampicin concentrations with an antibacterial activity up to 72 hours; this property disappears with the Knitted Dacron prostheses after only 24 hours. These results confirm the high affinity of Gelseal Dacron and Rifampicin also in in vivo experimental models.