Joseph Stoffel, Specialist Microbiology, 3M Medical Solutions Division
The healing trajectory of many chronic wounds, such as Venous leg ulcers (VLUs), can be affected by the presence of biofilm. As a microbiologist who studies wound biofilm at 3M’s Medical Solutions Division, here are my insights on the complexity of wound biofilm communities and antimicrobial effectiveness.
Antimicrobial effectiveness is often evaluated in laboratory environments where meaningful experiments can be conducted in controlled environments. However, the bacteria we encounter in our day-to-day lives aren’t typically what we see in the lab, and this poses significant challenges to antimicrobial effectiveness.
For instance, say we want to test if something can kill microbes. We will grow a test tube of bacteria, introduce an antimicrobial solution and check to see if any bacteria survived. If nothing survived, would it be considered a success?
Under FDA guidelines, this is how a typical test is performed; however, this test only proves that the solution can kill planktonic bacteria. Planktonic means free-floating; think plankton in the ocean, and in this state, bacterial cells are easily impacted by antimicrobial solutions with almost no barriers to interaction.
Here is the problem. Humans don’t typically live in the ocean or find themselves frequently suspended in liquid for extended periods. This can also be said for microorganisms living on our bodies or infecting tissue. Microbes typically attach to surfaces: from the ring in our toilets and showers to rocks in a stream and even on our teeth.
HOW DOES BIOFILM OCCUR?
As soon as microbes land on a surface, they get straight to work and secrete a protective slime layer known as an extra-polymeric substance or EPS. The presence of an EPS is a defining factor in resiliency when compared to planktonic organisms. The EPS can improve a microbe’s tolerance to environmental changes and often contain several different microorganisms living in the same biofilm. In some situations, cells within the biofilm can also “hibernate” thanks to an altered metabolic state. Protection from the EPS and the ability to hibernate are some of the prevailing factors for a cell’s ability to withstand external assaults from topical antimicrobial solutions.
BIOFILM IMPACT ON WOUND CARE
Biofilms have a significant impact on the treatment of chronic wounds and must be considered when developing an effective treatment plan. Studies by James et al¹ and Johani et al² indicate that microbial biofilms are present in almost every non-healing wound, triggering additional health complications such as chronic inflammation. Though not always visible to the naked eye, the evidence of a biofilm impacting healing may be noted when wound healing suddenly stalls or regresses.³
Clinicians will typically reach for topical antimicrobials in addition to other medical inventions, however, the FDA cleared antimicrobial products that receive antimicrobial status by testing against planktonic organisms that will likely not encounter the same organisms and conditions when treating real wounds.
Well, why aren’t we testing products against biofilms? The problem rests with the diversity of organisms in biofilm. Despite extensive literature in testing wound care products against biofilm models, none are standardized. This means that what may work for model A might be completely ineffective in model B. The lack of standardization also means that results may be altered to produce the desired result, making comparisons between antimicrobial solutions challenging.
Learn more about effective biofilm-based wound treatment plans.
Biofilm in chronic wounds poses significant challenges to treatment and recovery. Effective treatment plans require a specific biofilm-based approach that leverages consensus documents. Looking ahead, further research and standardization around antimicrobial product claims will be essential to providing the appropriate data for treatment decisions.4 To learn more about effective wound treatment, contact a 3M Account Representative.
Disclaimer: This article was originally written for a United States audience. The facts and sources cited therein may not be relevant in other regions.
1. James et.al. Wound Rep Regen. DOI:10.1111/j.1524-475X.2007.00321.x
2. Johani et. al. Int Wound J 2017; DOI:10.1111/iwj.12777
3. Percival SL, Bowler PG. Biofilms and their potential role in wound healing. Wounds 2004; 16: 234–40.
4. Snyder RJ, Bohn G, Hanft J, et al. Wound Biofilm: Current Perspectives and Strategies on Biofilm Disruption and Treatments. Wounds. 2017;29(6):S1-S17