Bioactive Polymers Grafted on Silicone to Prevent Staphylococcus Aureus Prosthesis Adherence: In Vitro and in VIVO Studies

Abstract

As joint prostheses become infected preventive strategies are needed. Silicone prostheses were coated with a COO – and SO₃ bearing bioactive copolymer, Q5, synthesized by radical polymerization and the adherence of Staphylococcus aureus (S. aureus)to them was evaluated in vitro and in vivo. Copolymer Q5 contains tris(trimethylsiloxy) methacryloxy propyl silane favoring the compatibility with the silicone matrix, cinnamoyl ethyl methacrylate allowing a network formation at the surface of the silicone prostheses, two ionic monomers: methacrylic acid and sodium styrene sulfonate. In vitro experiments were conducted on Q5-coated silicone lenses and on Q5-coated silicone prostheses. In both cases, materials were incubated with fibronectin (Fn) because of its important role in S. aureus adherence to implant surfaces. The percentage of adhesion inhibition was observed at approximately 40% for the coated materials compared to the untreated silicone. Rabbits underwent doubleblind partial knee replacements with Q5-coated or control implants fitted into the intramedullary canal of the tibia, and 10⁷ bacteria were injected into the knees. The number of bacteria adherent on the prostheses was determined 24 hr later. Significantly fewer bacteria adhered to Q5-coated than control prostheses (2.26 ± 0.76 vs 3.86 ± 0.54 log₁₀ CFU/ml; p < 0.0035). Bioactive polymer coating could provide a new method of preventing joint-prosthesis infections.