Introduction

Wound healing is a complicated process that restores the skin's barrier function to prevent further damage or infection. The healing process normally progresses through 4 phases: hemostasis, inflammation, proliferation, and remodeling. However, a chronic wound may result when a wound fails to progress through the normal phases of healing.¹ Although wound chronicity may be impacted by many factors, such as age, nutritional status, and underlying comorbidities, perhaps the most important factor that can impact healing is the presence of biofilm. Biofilm can cause chronic wounds to become locked in an inflammatory state, and the bacteria within biofilm are thought to be the root cause of approximately 80% of all infections in humans.²

How the Presence of Biofilm Impacts Wound Care

The bacteria within biofilm differ from planktonic bacteria in their structure, gene expression, antibiotic resistance, and interaction with the host. These microbial cells, which reside in the extracellular polymeric substance (EPS), typically occupy 5% to 30% of the volume of the biofilm. Within the EPS, these bacteria are far more resistant to antibiotics and biocides, thus making biofilm difficult to manage.³ Poor antibiotic penetration, nutrient limitation, slow growth, adaptive stress responses, and the formation of phenotypic variants are thought to contribute to this resistance.⁴ In some conditions, biofilm bacteria have a 10-fold higher treatment survival rate than planktonic bacteria.⁵

Biofilm Formation in Chronic Wounds

Chronic wounds provide the ideal environment for biofilm formation. The presence of necrotic tissue and debris allows for bacterial attachment, and these wounds are susceptible to infection as a result of an impaired immune response. Sixty percent of chronic wound specimens contain biofilm, whereas only 6% of acute wounds contain biofilm.³ The type and relative number of bacteria in biofilms can differ significantly from wound to wound, and mature biofilms can develop in chronic wounds in as little as 10 hours.⁶

Treatment and Management of Biofilm: Methods

Given that biofilms can be resistant to antibiotics, the prevention and management of biofilm pose a challenge.⁶ However, treating wounds with biofilm is urgent because of the risk of amputation or surgical intervention. Treatment regimens should consider the impact of biofilm and target its unique characteristics. Standard of care within biofilm management entails a combination of treatments,

Debridement

Sharp Debridement Sharp debridement is the most common form of debridement used within the standard of care in biofilm management.⁷ This method physically removes biofilm as well as tissues that sustain the bacteria within biofilm, such as necrotic tissue and other forms of devitalized tissue. This removal is achieved with instruments such as a scalpel, curette, scissors, rongeur, and forceps.⁷ Although decidedly one of the most crucial components of biofilm management, debridement cannot definitively remove all biofilm, and therefore, it should not be used as monotherapy.⁸ Topical surfactant-based wound cleansing agents may also assist in the debridement process by lowering surface tension at the biofilm interface.⁹Ultrasonic Debridement Especially in clinical scenarios where pain or other factors will contribute to difficulty tolerating sharp debridement, ultrasonic debridement can treat biofilm-infected wounds and increase antibiotic effectiveness in promoting healing in chronic wounds. Additionally, ultrasound debridement often requires fewer treatments than sharp debridement and is often less painful for patients. It is recommended to use ultrasound debridement 3 times a week.¹⁰

Dressings With Biofilm-Related Actions

Dressings with agents impacting biofilm may also be used, adjunctive to debridement, to prevent and manage biofilm and encourage wound closure. Examples of such dressings include those with polyhexamethylene biguanide, shown to have antibiofilm effects against a variety of pathogens.^11,12 Cadexomer iodine, silver, acetic acid, and honey are also among discussed agents used to prevent recurrent biofilm formation or to act against microorganisms.^9,13

Conclusion

Biofilm clearly poses a challenge to healing in chronic wounds and should be a factor clinicians consider when formulating a treatment plan. Debridement (ideally sharp) is crucial for biofilm management, but supplementation and augmentation with targeted dressings are also important measures. Research and related findings continue to evolve, and it behooves the wound care professional to follow the available data to stay abreast of best practices in biofilm management.

References

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11. Zheng Y, Wang D, Ma LZ. Effect of polyhexamethylene biguanide in combination with undecylenamidopropyl betaine or PslG on biofilm clearance. Int J Mol Sci. 2021;22(2):768. doi:10.3390/ijms22020768. Accessed August 21, 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828725/
12. Kamaruzzaman NF, Chong SQY, Edmondson-Brown KM, Ntow-Boahene W, Bardiau M, Good L. Bactericidal and anti-biofilm effects of polyhexamethylene biguanide in models of intracellular and biofilm of Staphylococcus aureus Isolated from bovine mastitis. Front Microbiol. 2017;8:1518. doi:10.3389/fmicb.2017.01518 Accessed August 21, 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5554503/
13. Roche ED, Woodmansey EJ, Yang Q, Gibson DJ, Zhang H, Schultz GS. Cadexomer iodine effectively reduces bacterial biofilm in porcine wounds ex vivo and in vivo. Int Wound J. 2019;16(3):674-683. doi:10.1111/iwj.13080 Accessed August 21, 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850490/