An Increased Concentration of Rifampicin Bonded to Gelatin-Sealed Dacron Reduces the Incidence of Subsequent Graft Infections following a Staphylococcal Challenge

Abstract

The purpose of this study was to determine if 10 mg/ml rifampicin bonded to gelatin-sealed Dacron (Gelsoft) reduced staphylococcal infection. Grafts soaked in rifampicin were interposed in the left carotid artery of 20 merino sheep and then inoculated with 10⁸ colony-forming units of MRSA (10 sheep) or a slime producing Staphylococcus epidermidis (10 sheep). Grafts were harvested at 3 weeks, and perigraft abscess, anastomotic disruption and graft occlusion recorded. Swabs were taken to assess bacterial growth of the perigraft tissues, and external and internal graft surface. Grafts segments were incubated in broth medium. Results were compared with previously published results that used graft that were not soaked in rifampicin (control) and grafts soaked in 1.2 mg/ml rifampicin. A total of 4/50 cultures were positive and significantly reduced for S. epidermidis compared with the control group of 30/50 (P < 0.05) and the 1.2 mg/ml group of 13/45 (P < 0.05). For the methicillin resistant staphylococcus aureus (MRSA) group, 6/40 cultures were positive, which was significantly reduced compared with the control group (38/40, P < 0.05) and the 1.2-mg/ml group (19/32, P < 0.05). In conclusion an increased concentration of rifampicin significantly reduced the incidence of prosthetic vascular graft infection following a challenge of MRSA or S. epidermidis.