The addition of lysostaphin dramatically improves survival, protects porcine biomesh from infection, and improves graft tensile shear strength

Background: Lysostaphin (LS), a naturally occurring Staphylococcal endopeptidase, has the ability to penetrate biofilm, and has been identified as a potential antimicrobial to prevent mesh infection. The goals of this study were to determine if LS adhered to porcine mesh (PM) can impact host survival, reduce the risk of long-term PM infection, and to analyze lysostaphin bound PM (LS-PM) mesh-fascial interface in an infected field. Methods: Abdominal onlay PMs measuring 3 × 3 cm were implanted in select groups of rats (n = 75). Group assignments were based on bacterial inoculum and presence of LS on mesh. Explantation occurred at 60 d. Bacterial growth and mesh-fascial interface tensile strength were analyzed. Standard statistical analysis was performed. Results: Only one out of 30 rats with bacterial inoculum not treated with LS survived. All 30 LS treated rats survived and had normal appearing mesh, including 20 rats with a bacterial inoculum (10 ⁶ and 10 ⁸ CFU). Mean tensile strength for controls and LS and no inoculum samples was 3.47 ± 0.86N versus 5.0 ± 1.0N (P = 0.008). LS groups inoculated with 10 ⁶ and 10 ⁸ CFU exhibited mean tensile strengths of 4.9 ± 1.5 N and 6.7 ± 1.6 N, respectively (P = 0.019 and P < 0.001 compared with controls). Conclusion: Rats inoculated with S. aureus and not treated with LS had a mortality of 97%. By comparison, LS treated animals completely cleared S. aureus when challenged with bacterial concentrations of 1 × 10 ⁶ and 1 × 10 ⁸ with maintenance of mesh integrity at 60 d. These findings strongly suggest the clinical use of LS-treated porcine mesh in contaminated fields may translate into more durable hernia repair.