Control of prosthetic bacterial infection: evaluation of an easily incorporated, tightly bound, silver antibiotic PTFE graft.

Despite the use of prophylactic antibiotics in vascular surgery, prosthetic infection rate remains 2-5%. Antibiotics bound to vascular prostheses can control experimentally induced infection but prolonged antibacterial activity has not been achieved. This study evaluates the in vivo efficacy and antibiotic retention of an easily prepared silver-antibiotic prosthesis. Prostheses were prepared by combining silver with oxacillin or amikacin using an organic solvent. After evaporation of the solvent, the graft was left impregnated with the antibiotic complex. In vivo retention studies were performed by implanting PTFE 110Ag-oxacillin prostheses in four canine abdominal aortas. When prostheses were explanted at 1 week, mean antibiotic retention was found to be 20% of original activity, higher than the mean inhibitory concentration for Staphylococcus aureus. In three groups of five dogs, 20 X 7-mm prostheses of PTFE alone, PTFE silver-oxacillin, or PTFE silver-amikacin were implanted in the abdominal aorta and the grafts were inoculated with 10(7) S. aureus of a known bacteriophage type, in a closed retroperitoneal pocket. The animals were sacrificed at 1 week and the prostheses were excised for quantitative bacterial culture. PFTE silver-oxacillin, and PTFE silver-amikacin prostheses had 1.7 X 10(2) and 2.0 X 10(2) colonies, respectively, significantly less (P less than 0.05) than controls (1.3 X 10(6) colonies). These data suggest that antibiotic prostheses can be easily prepared without binding agents. They retain the bound antibiotic for a prolonged period and are effective in reducing graft infection in a stringent direct contamination model.