A guide to biofilm in veterinary wounds

Biofilms occur when a group of microorganisms (typically bacteria, fungi, parasites and viruses) attach themselves to a surface to create a colony. This colony form themselves into a type of ‘shield’ which has a glue-like or slimy consistency (Figure 1). Biofilms act as a barrier to the wound and help the colony to defend itself against antimicrobial treatments and immune cells (Curtis, 2020). This may be the reason that some wounds can be difficult to heal, why persistent infections may keep recurring and why antimicrobial resistance may be seen in some wounds in veterinary practice.

Antimicrobial resistance is a key concern in veterinary practice, via the One Health initiative, and refers to the ability of any microbes to resist treatment to drugs designed to kill them or stop their growth (HM Government, 2023).

Free-floating microbes attach to the wound almost immediately and within 2–4 hours the bacteria have formed micro-colonies that securely attach to the wound (Curtis, 2020). The colony grows and matures between 2 and 4 days later (Figure 2). From the mature biofilm, bacteria can then disperse and attach to another area of the wound surface. This continues until the whole surface of the wound is covered with biofilm. This attachment can be reversible; however, it will require specific treatment. The colony secretes material that provides a structural matrix, similar to cement. These structures can adhere to surfaces and on medical materials, which can be the cause of hospital-acquired infections (Phillips et al, 2010).