TREATMENT OF VASCULAR GRAFT INFECTION BY IN-SITU REPLACEMENT WITH A RIFAMPIN-BONDED GELATIN-SEALED DACRON GRAFT

Purpose: The purpose of this study was to treat an established prosthe tic vascular graft infection by in situ replacement with a rifampin-bo nded gelatin-sealed Dacron graft in an animal model. Methods: The infr arenal aorta of 18 dogs was replaced with a gelatin-sealed graft conta minated in vitro by soaking it in a solution with Staphylococcus epide rmidis. One week later, animals were randomized into three groups. In group I (control, (n = 6), the dogs did not undergo repeat operations. The dogs in groups II and III underwent repeat operation. In these an imals the infected grafts were removed for bacteriologic analysis and replaced in situ with one of two types of grafts: group II (n = 6) rec eived an untreated, gelatin-sealed graft; group III (n = 6) received a rifampin-bonded, gelatin-sealed graft. Antibiotic bonding was obtaine d by soaking grafts for 15 minutes in a 60 mg/ml saline solution of ri fampin at 37 degrees C. All 18 dogs received no systemic adjunct antib iotic therapy. Control grafts and replacement grafts were removed 4 we eks after the initial implantation for bacteriologic analysis. When ha rvested, all the grafts were cut into two fragments, and quantitative bacterial cultures were obtained from all the fragments. Results were expressed as colony-forming units (CFU)/cm(2) of graft material. Resul ts: All is initially implanted grafts and all the untreated replacemen t grafts were grossly infected at the time of removal, whereas all the rifampin-bonded replacement grafts had normal incorporation. None of the rifampin-bonded grafts grew bacteria, whereas all the initially im planted and all the untreated replacement grafts were infected (p < 0. 01). Bacterial counts from the infected fragments were similar in cont rol grafts (2.6 +/- 1.9 x 10(6) CFU/cm(2)), in initially implanted gra fts of groups II (9 +/- 1.1 x 10(5) CFU/cm(2)) and III (1.3 +/- 1.5 x 10(6) CFU/cm(2)), and in untreated replacement grafts of group II (1.7 +/- 2.5 x 10(6) CFU/cm(2)), Blood culture results and culture results of liver, spleen, kidney, and lung specimens at the time of sacrifice were negative. Conclusion: This study demonstrates that rifampin-bond ed gelatin-sealed Dacron grafts are resistant to infection when used f or in situ replacement of an infected graft in the dog.