In vitro and in vivo comparisons of staphylococcal biofilm formation on a cross-linked poly(ethylene glycol)-based polymer coating

Poly(ethylene glycol) (PEG) coatings are known to reduce microbial adhesion in terms of numbers and binding strength. However, bacterial adhesion remains of the order of 104 cm−2. It is unknown whether this density of bacteria will eventually grow into a biofilm. This study investigates the kinetics of staphylococcal biofilm formation on a commercially produced, robust, cross-linked PEG-based polymer coating (OptiChem®) in vitro and in vivo. OptiChem® inhibits biofilm formation in vitro, and although adsorption of plasma proteins encourages biofilm formation, microbial growth kinetics are still strongly delayed compared to uncoated glass. In vivo, OptiChem®-coated and bare silicone rubber samples were inserted into an infected murine subcutaneous pocket model. In contrast to bare silicone rubber, OptiChem® samples did not become colonized upon reimplantation despite the fact that surrounding tissues were always culture-positive. We conclude that the commercial OptiChem® coating considerably slows down bacterial biofilm formation both in vitro and in vivo, making it an attractive candidate for biomaterials implant coating.