Biofilm Management in Wound Care

Abstract

Learning objectives: After studying this article, the participant should be able to: 1. Understand the basics of biofilm infection and be able to distinguish between planktonic and biofilm modes of growth. 2. Have a working knowledge of conventional and emerging antibiofilm therapies and their modes of action as they pertain to wound care. 3. Understand the challenges associated with testing and marketing antibiofilm strategies and the context within which these strategies may have effective value.

Summary: The Centers for Disease Control and Prevention estimate for human infectious diseases caused by bacteria with a biofilm phenotype is 65 percent and the National Institutes of Health estimate is closer to 80 percent. Biofilms are hostile microbial aggregates because, within their polymeric matrix cocoons, they are protected from antimicrobial therapy and attack from host defenses. Biofilm-infected wounds, even when closed, show functional deficits such as deficient extracellular matrix and impaired barrier function, which are likely to cause wound recidivism. The management of invasive wound infection often includes systemic antimicrobial therapy in combination with débridement of wounds to a healthy tissue bed as determined by the surgeon who has no way of visualizing the biofilm. The exceedingly high incidence of false-negative cultures for bacteria in a biofilm state leads to missed diagnoses of wound infection. The use of topical and parenteral antimicrobial therapy without wound débridement have had limited impact on decreasing biofilm infection, which remains a major problem in wound care. Current claims to manage wound biofilm infection rest on limited early-stage data. In most cases, such data originate from limited experimental systems that lack host immune defense. In making decisions on the choice of commercial products to manage wound biofilm infection, it is important to critically appreciate the mechanism of action and significance of the relevant experimental system. In this work, the authors critically review different categories of antibiofilm products, with emphasis on their strengths and limitations as evident from the published literature.

Trial registration: ClinicalTrials.gov NCT02577120 NCT02294175.

Copyright © 2021 by the American Society of Plastic Surgeons.

Figures

Figure 1.. 3D imaging of biofilm and host immune cells.

Porcine burn wound tissue infected with Pseudomonas aeruginosa and Acinetobacter baumannii mixed species biofilm were processed and imaged using STEM/FIB-SEM imaging. Shown is a representative 3D image created from individual slices generated by the imager. Phagocytic cells are shown in pink interacting with extrapolymeric substance (EPS; grey haze, red arrow head) coated biofilm aggregates of P.aeruginosa (purple) and A.baumannii (green). Some of the phagocytic cells in this image appear to be disintegrating (yellow arrow head).

Figure 2.. Aggressive tangential excision is not sufficient to eliminate biofilm infection: A case report.

A 82Y Caucasian male sustained 37% TBSA burns to his left lower extremity and posterior trunk. Upon presentation to the ED had escharotomy on left leg and was admitted to SICU for fluid resuscitation using West Penn formula. Prior to excision all burn wounds were dressed with silvadene. On post-burn day (PBD) 3 he was taken to the OR for debridement and grafting of his left lower extremity. He had aggressive tangential excision to fascia on the leg and split-thickness skin graft coverage of his lower extremity burns. The post-debridement fascial wound bed was biopsied and tested positive for biofilm infection by SEM as shown. On PBD 6 he was taken back to the OR for excision and grafting of the remainder of his burn wounds on his posterior trunk and thigh. All grafts were treated with Sulfamylon soaks (5% solution). The patient had poor graft take at the site of the wound tissue biopsy with >30% graft loss. The patient developed progressive organ failure and died on PBD18.

Figure 3.. Biofilm in a central-line catheter taken from an in-patient with burn injury.

A. Island of biofilm cells (green) embedded in matrix (gold) in lumen of catheter. B. Collection of bacteria embedded in matrix surrounding red blood cells (red) in catheter tip.

Figure 4.

Levels of Evidence modified for Anti-biofilm strategies.