Comparing the Antimicrobial Effect of Silver Ion-Coated Silicone and Gentamicin-Irrigated Silicone Sheets from Breast Implant Material

Background: Post-operative infection is a significant complication of breast implant surgery that may require extensive use of antibiotics and surgical interventions. Here, we developed a biomaterial coating that is chemically bonded to silicone implants which delivers antimicrobial ions over time. Methods: After coating the silicone implants with a “mediator” polymer (γ-PGA), the implants were impregnated with silver (Ag) ions. Antimicrobial effects of these implants were assayed with modified Kirby-Bauer disk diffusion method. The silicone disks were transferred to a plate with fresh bacteria. Control was intended to simulate an intra-operative wash. Results: The Ag-γ-PGA coated silicone demonstrated antimicrobial effects against the most common etiological agents of breast implant infections, including Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae. There was no effect of inhibition of bacterial growth around the control silicone or the silicone coated only with γ-PGA. The zone of inhibition was generally larger around the Ag-γ-PGA coated silicone as compared to the silicone irrigated with gentamicin, and continued antibacterial effect was also observed at 48 hours in the Ag-γ-PGA coated silicone for all bacteria groups with the exception of P. aeruginosa. Gentamicin-irrigated silicone did not inhibit bacterial growth at 48 hours. Conclusion: The observed antibacterial performance of the Ag-γ-PGA coating as compared to simulated intra-operative antibiotic wash is promising and should be further evaluated to develop the next generation of implants with diminished risk for post-operative implant infections.