ANTIBACTERIAL ACTIVITY OF ANTIBIOTIC COATED SILICONE GRAFTS

Purpose: Postoperative infection remains one of the most; serious comp lications of implantation of penile prostheses. Attempts to reduce the rate of infection by spraying the prosthesis with an antibiotic solut ion prior to implantation, along with perioperative antibiotics, have failed to eradicate infection. No published studies have evaluated the effect of antibiotic coating of penile prostheses. In this study, we evaluate the antibacterial effect of antibiotic-coated silicone strips as a surrogate for the penile prosthesis. Materials and Methods: Stri ps coated with several different antibiotics were dipped in bacterial solutions containing Staphylococcus epidermidis or S. aureus and impla nted subcutaneously in adult Sprague-Dawley rats. After a week, the st rips were removed, and the number of bacteria on the strips and in the surrounding tissue were determined. The in vitro antibiotic activity of the antibiotic-coated strips against the same organisms was also de termined. Results: In the group of rats that received silicone strips contaminated in vitro with S. epidermidis, six of nine control rats yi elded strips and tissues containing heavy bacterial growth. None of si x strips coated with rifampin/minocycline yielded bacterial growth, no r did any of the seven strips coated with vancomycin. One of seven rat s that received amikacin-coated strips had infection of the strip. The tissue results were similar to the strip results. In the group using S. aureus as the contaminating bacterium, the strips and tissues from eight of nine control rats yielded bacteria. None of the six rifampin/ minocycline-coated strips yielded bacteria, while two of seven vancomy cin-treated strips and two of six amikacin-coated strips were infected with S. aureus. The difference in bacterial growth between controls a nd antibiotic-coated strips reached a level of statistical significanc e for the rifampin/minocycline and vancomycin groups and was highly si gnificant for the rifampin/minocycline groups. Conclusion: The experim ental results presented here suggest that coating silicone graft mater ial with antibiotics, particularly rifampin/minocycline, can reduce th e incidence of graft; colonization in contaminated wounds in rats, eve n in the absence of systemic antibiotics. These graft materials may pr ove useful in preventing the infection of penile prostheses.