Use of an antibiotic-bonded graft for in situ reconstruction after prosthetic graft infections

Abstract We have developed an infection resistant vascular prosthesis by bonding rifampin to Dacron grafts with the use of a collagen matrix release system. The purpose of this study was to determine the efficacy of this antibiotic-bonded graft in resisting infection after an in situ reconstruction of a previously infected prosthetic bypass. Eighty-three adult mongrel dogs underwent implantation of a 3 cm untreated Dacron graft into the infrarenal aorta. This initial graft was deliberately infected, at the time of operation, with 10 2 organisms of Staphylococcus aureus by direct inoculation. One week later, the dogs were reexplored, the retroperitoneum debrided, and the animals randomized to undergo an end-to-end in situ graft replacement with either one of two types of prosthetic grafts: group I (collagen, n = 36) received control collagen-impregnated knitted Dacron grafts; group II (rifampin, n = 47) received experimental collagen-rifampin-bonded Dacron grafts. Each group of animals was then subdivided to receive one of four treatment protocols: (a) no antibiotic therapy, (b) cephalosporin peritoneal irrigation solution (cefazolin 500 mg/1000 ml) during operation and two doses of cephalosporin (cefazolin, 500 mg intramuscularly) postoperatively, (c) treatment as in protocol group b plus 1 week of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily), and (d) treatment as in protocol group b plus 2 weeks of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily). All grafts were sterilely removed between 3 and 4 weeks after implantation. There were no anastomotic disruptions and all grafts were patent at the time of removal. Cultures were obtained from the grafts and peri-graft tissues separately. Analysis included determination of the culture positivity of tissue and graft samples combined and of the graft segments alone irrespective of the results of the surrounding tissue cultures. Results were expressed as the percentage of animals that had culture positive results at sacrifice. For group I, collagen graft animals, the rate of infection in graft segments alone was 100%, 87.5%, 100%, and 80% when the animals received supplemental antibiotic therapy according to groups a through d as described, respectively. For group II, rifampin graft animals, the corresponding values were 50%, 50%, 20%, and 20%. When overall infection rates were evaluated, samples from dogs in group I were culture positive in 100%, 87.5%, 100%, and 80% of the animals in each of the supplemental antibiotic therapy groups, respectively. In group II animals, the corresponding positivity rates for overall infection were 62.5%, 62.5%, 60%, and 20%. In all four treatment groups the reduction of positive graft cultures after in situ replacement of a previously infected aortic prosthesis with a collagen-rifampin-bonded graft was statistically significant. When overall infection rates were evaluated, this reduction was statistically significant only in the subset of animals treated with 2 weeks of supplemental antibiotics. We conclude that the collagen-rifampin-bonded graft reduces the incidence of graft colonization after in situ replacement of an infected graft. A course of supplemental antibiotics is required to sterilize the surrounding peri-graft tissues. (J Vasc Surg 1992;16:651–60.)