A chlorhexidine-releasing epoxy-based coating on titanium implants prevents Staphylococcus aureus experimental biomaterial-associated infection

Prevention of biomaterial-associated infections (BAI) remains a challenging problem, in particular due to the increased risk of resistance development with the current antibiotic-based strategies. Metallic orthopaedic devices, such as non-cemented implants, are often inserted under high mechanical stress. These non-cemented implants cannot be protected by e.g. antibiotic-releasing bone cement or other antimicrobial approaches, such as the use of bioactive glass. Therefore, in order to avoid abrasion during implantation procedures, we developed an antimicrobial coating with great mechanical stability for orthopaedic implants, to prevent Staphylococcus aureus BAI. We incorporated 5 and 10 wt % chlorhexidine in a novel mechanically stable epoxy-based coating, designated CHX 5 and CHX 10 , respectively. The coatings displayed potent bactericidal activity in vitro against S. aureus, with over 80% of the release (19 μg/cm 2 for CHX 5 and 41 μg/ cm 2 for CHX 10 ) occurring within the first 24 h. In mice, the CHX 10 coating significantly reduced the number of CFU (colony forming units), both on the implants and in the peri-implant tissues, 1 d after S. aureus challenge. The CHX 10 -coated implants were well-tolerated by the animals, with no signs of toxicity observed by histological analysis. Moreover, the coating significantly reduced the frequency of culture-positive tissues 1 d, and of culture-positive implants 1 and 4 d after challenge. In summary, the chlorhexidine-releasing mechanically stable epoxy-based CHX 10 coating prevented implant colonisation and S. aureus BAI in mice and has good prospects for clinical development.