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

Background: Propionibacterium 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.

Aim: To 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.

Methods: A 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.

Findings: The 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.

Conclusion: Based 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.