Topical antimicrobial protection of postoperative surgical sites at risk of infection with Propionibacterium acnes: an in-vitro study

SummaryBackgroundPropionibacterium acnes is an increasingly recognized pathogen in surgical site infections, particularly in relation to joint replacements and spinal procedures. Due to its low virulence and slow-growing nature, clinical signs of infection may be prolonged, and diagnosis is often challenging. As a consequence, appropriate presurgical skin preparation and postsurgical protection of the wound using antimicrobial dressings are important considerations in the prevention of surgical site infections caused by P. acnes.AimTo investigate the antimicrobial efficacy of a silver-containing gelling fibre wound dressing against P. acnes using stringent in-vitro models that simulated a variety of wound conditions.MethodsA simulated wound fluid model was used to quantify the killing capacity of the silver-containing dressing over time under conditions that mimicked a heavily exuding wound. A simulated colonized shallow wound model was used to investigate the impact of dressing conformability on antimicrobial activity, and a third model was designed to measure the efficacy of the dressing on bacteria embedded within a simulated colonized wound surface.FindingsThe in-vitro data demonstrated that the silver-containing wound dressing was bactericidal against P. acnes, it maintained its killing effect over a prolonged period (seven days) under conditions simulating excessive exudate, and the gelled dressing matrix (following hydration) enabled the dressing to conform to a simulated wound topography, thus optimizing antimicrobial activity in a shallow wound model.ConclusionBased on the in-vitro data generated, use of the silver-containing dressing as part of a postoperative care protocol may help to minimize the risk of prolonged and debilitating surgical site infections caused by P. acnes.