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±0.86 N versus 5.0±1.0 N (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.