Skip to main content

How to Identify Biofilm in a Wound

One of my favorite topics to discuss in wound care is biofilms. When I conduct wound care in-services or trainings, I always ask the audience, "Who wants to tell me what a biofilm is?" There is silence. From that point, I proceed to tell my little story about biofilms. It sounds a little like this...You know when we go to bed at night, get up in the morning and feel that sticky film on our teeth? We brush our teeth with a minty-fresh toothpaste. Now our teeth feel clean. By the next morning, that sticky, fuzzy feeling returns, right? Or, when your pet's water dish develops that slimy swamp layer and then you change it? Well that, my folks, is a biofilm! Think of those bright shiny red granulating wounds that become stagnant. We start throwing all sorts products on the wound, and nothing is working. Or maybe you see wound healing progress for a few weeks, and then it stalls again. My analogy might seem silly, but the health care professionals and patients that I educate remember it.

How to Identify a Biofilm

I think of biofilms as intelligent, diabolical creatures! When wound progress becomes stagnant for about 3-4 weeks, you should be suspicious of a biofilm colony. Many times biofilms are not seen. They are microscopic, but can present themselves as a shiny film. There are no signs and symptoms of infection. When the biofilm become larger, you can then identify them much easier. Biofilms are usually composed of mixed strains of bacteria, fungi, yeasts, algae, microbes, and other cellular debris. A biofilm is formed when certain types of microorganisms adhere themselves to the wound surface. A viscous substance is then secreted.

Why Biofilms Can Be a Challenge

Antibiotics are designed to attack bacteria, and may only partially eliminate the bacteria contained within a biofilm. The dense exopolymeric material (EPM) matrix actually paralyzes large antibodies and neutralizes microbicides. A biofilm is capable of promoting anaerobic bacteria growth, synergism between different bacteria, generating MRSA-resistant proteins, producing negative charges of polysaccharides and DNA bind cationic molecules like Ag+, antibiotics, and polyhexamethylene biguanide. This is why clinical studies show 60% of chronic wounds contain a biofilm, and can again reform in three days after sharp debridement. The wound appears to be healing, then becomes stagnant again.


The progressive development of biofilm.

Ways to Manage a Biofilm

Sequential sharp debridement of wounds will disrupt the biofilm growth and promote faster healing. Treating wounds with an antimicrobial or bacteriostatic dressing in an alginate or polymeric foam form will help prevent reformation of biofilms. Dressings impregnated with silver, cadexomer iodine, and methylene blue are at the top of the list. Stay away from gauze impregnated dressings and skin graft application, as this is the perfect food source environment for biofilms. Systemic antibiotics are used to destroy the biofilm microbes and prevent reseeding of bacteria on the wound surface. Maggot debridement therapy has been reintroduced for the treatment of chronic wounds. Studies have shown that the excretions/secretions of maggots contain many bioactive compounds.

"Biofilm has a 3D architecture and is like Facebook for bugs." -Mara Williams.


Harris LG, Bexfield A, Nigam Y, Rohde H, Ratcliffe NA, Mack D. Disruption of Staphylococcus epidermidis biofilms by medicinal maggot Lucilia sericata excretions/secretions. Int J Artif Organs. 2009 Sept;32(9):555-64.

Phillips PL, Yang Q, Davis S, et al. Antimicrobial dressing efficacy against mature Pseudomonas aeruginosa biofilm on porcine skin explants. Int Wound J. 2015 Aug;12(4):469-83. doi: 10.1111/iwj.12142

Stechmiller JK, Schultz G. Implementing Biofilm and Infection 2014 Guidelines. National Pressure Ulcer Advisory Panel. Available at…

Wolcott RD, Rhoads DD. A study of biofilm-based wound management in subjects with critical limb ischemia. J Wound Care. 2008 Apr;17(4):145-8, 150-2, 154-5.

About the Author

Cheryl Carver is an independent wound educator and consultant. Carver's experience includes over a decade of hospital wound care and hyperbaric medicine. Carver single-handedly developed a comprehensive educational training manual for onboarding physicians and is the star of disease-specific educational video sessions accessible to employee providers and colleagues. Carver educates onboarding providers, in addition to bedside nurses in the numerous nursing homes across the country. Carver serves as a wound care certification committee member for the National Alliance of Wound Care and Ostomy, and is a board member of the Undersea Hyperbaric Medical Society Mid-West Chapter. 

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, HMP Global, its affiliates, or subsidiary companies.