Protection with a collagen wound matrix containing polyhexamethylene biguanide supports innate wound healing in biofilm-infected porcine wounds

Over 90% of chronic wounds have biofilm infections, making the need for inhibiting reformation of biofilm post-debridement paramount to support progression through the normal phases of wound healing. Herein, we describe a porcine wound model infected with methicillin-resistant Staphylococcus aureus (MRSA) and examine the ability of an antimicrobial barrier composed of native type I collagen and polyhexamethylene biguanide (PCMP) to serve as a barrier to protect wounds and support progression through the innate wound healing cascade. Wounds were inoculated with MRSA and allowed to form a biofilm for 72 h, subjected to standard of care sharp debridement, then either left untreated or received PCMP for 5, 10, 15 or 20 days. Wounds were assessed for bioburden, wound closure and expression of genes related to wound healing. Wounds treated with PCMP exhibited statistically lower MRSA levels compared to untreated controls and achieved 90% closure by 2 weeks of treatment. Gene expression analysis demonstrated that by reducing bacterial load, wounds progressed through the innate wound healing cascade, while untreated wounds exhibited a dampening of the immune response. Additionally, for randomly assigned wounds, PCMP was not reapplied at dressing changes to assess the impact of inconsistent wound protection. At all timepoints, a resurgence in bioburden was observed following removal of PCMP if the wounds had not fully closed. This study highlights the value of PCMP as an antimicrobial barrier and the importance of protecting wounds through closure and resolution.