Graft-preserving treatment for vascular graft infected with Staphylococcus aureus with antibiotic-releasing porous apatite ceramic in the rabbit

This study was undertaken to investigate whether infection of a vascular graft with Staphylococcus aureus can be treated in situ by applying antibiotic-loaded porous apatite ceramic, in a rabbit model. Teicoplanin (TEIC) was loaded onto a β-tricalcium phosphate (TCP) block, a type of porous apatite ceramic. The activity of TEIC released from the antibiotic-loaded TCP block was examined in vivo. A vascular graft was patched onto the abdominal aorta in 24 rabbits, and S aureus was applied directly on it. Seven days postoperatively, each rabbit underwent repeat laparotomy, and retroperitoneal abscess around the prosthetic vascular patch was debrided. Animals were divided into four groups of 6 rabbits each. In group 1 only debridement was carried out. In groups 2 and 3, solution containing 40 or 60 mg of TEIC, respectively, was applied to the prosthetic vascular patch. In group 4, an antibiotic-loaded TCP block (63 ± 6.6 mg of TEIC) was placed around the graft. Three weeks after the second operation, the graft, the tissue around it, and arterial blood were collected and cultured. TEIC activity was maintained for 28 days in vivo. In group 1, bacterial cultures of the prosthetic vascular graft and the tissue around it were positive in 5 animals and negative in 1 animal (infection rate, 83%). In both groups 2 and 3, cultures were positive in 3 animals and negative in 3 animals (infection rate, 50%). In group 4, cultures were negative in all animals (infection rate, 0%). Blood cultures were negative in all animals. Infection rate in group 4 was significantly lower than that in group 1 ( P = .03), and was also lower than that in groups 2 and 3, but the difference was not significant. Use of slow-release antibiotic loaded onto a TCP block, along with debridement, may control infection in vascular grafts in situ, averting the necessity to remove the graft.