The prevalence of biofilms in chronic wounds: a systematic review and meta-analysis of published data.

Evidence of biofilms in human chronic wounds are thought to be responsible for preventing healing in a timely manner. However, biofilm evidence in horse wounds has not yet been documented. Consequently, this study aimed to determine whether biofilms could be detected in wounds, and to investigate the microbiology of chronic wounds in horses. Prior to analysis, wound surfaces were irrigated with 5 mL of sterile saline to remove debris. All wounds were swabbed twice (1 cm2 area) using sterile cotton-tipped swabs. In addition to this, 2 tissue biopsies were taken to investigate evidence of biofilm and the microbiology richness of the wounds. All swabs and 1 biopsy sample were transported to the laboratory in Robertson's cooked meat broth. Traditional culturable techniques and denaturing gradient gel electrophoresis with PCR were utilized to identify common bacteria isolated in all wounds. Following analysis of a number of the biopsy samples, biofilms could be clearly seen. The most common bacteria isolated from each wound analysed included Pseudomonas aeruginosa, Staphylococcus epidermidis, Serratia marcescens, Enterococcus faecalis, and Providencia rettgeri. Sequencing of the 16S ribosmonal DNAs, selected on the basis of DGGE profiling, enabled identification of bacterial species not identified using culturable technology. This study is the first to identify biofilms in the chronic wounds of horses. In addition, this study also demonstrated the importance of combining DGGE-PCR with culture techniques to provide better microbiology analysis of chronic wounds.

The incidence, cost, morbidity, and mortality associated with non-healing of chronic skin wounds are dramatic. With the increasing numbers of people with obesity, chronic medical conditions, and an increasing life expectancy, the healthcare cost of non-healing ulcers has recently been estimated at $25 billion annually in the United States. The role played by bacterial biofilm in chronic wounds has been emphasized in recent years, particularly in the context of the prolongation of the inflammatory phase of repair. Rapid high-throughput genomic approaches have revolutionized the ability to identify and quantify microbial organisms from wounds. Defining bacterial genomes and using genetic approaches to knock out specific bacterial functions, then studying bacterial survival on cutaneous wounds is a promising strategy for understanding which genes are essential for pathogenicity. When an animal sustains a cutaneous wound, understanding mechanisms involved in adaptations by bacteria and adaptations by the host in the struggle for survival is central to development of interventions that favor the host. Characterization of microbiomes of clinically well characterized chronic human wounds is now under way. The use of in vivo models of biofilm-infected cutaneous wounds will permit the study of the mechanisms needed for biofilm formation, persistence, and potential synergistic interactions among bacteria. A more complete understanding of bacterial survival mechanisms and how microbes influence host repair mechanisms are likely to provide targets for chronic wound therapy.

Chronic wounds, and among these infected diabetic foot ulcers, are a worldwide problem. The poor treatment outcomes result in high healthcare costs, amputations, a decreased quality of life, and an increased mortality. These outcomes are influenced by several factors, including biofilm formation. A biofilm consists of pathogenic bacteria that are encased in an exopolysaccharide layer and communicate through secretion of signaling molecules. Bacteria that live in a biofilm are refractory to host responses and treatment. We performed a nonsystematic review of the currently published to-date medical biofilm literature. The review summarizes the evidence of biofilm in chronic wounds, the role of biofilm in wound healing, detection of biofilm, and available antibiofilm treatments. Articles containing basic science and clinical research, as well as systematic reviews, are described and evaluated. The articles have variable levels of evidence. All articles have been peer reviewed and meet the standards of evidence-based medicine. Both animal and human studies have identified biofilm in chronic wounds and have suggested that healing might be influenced by its presence. A promising development in biofilm detection is rapid molecular diagnostics combined with direct microscopy. This technique, rather than classic culture, might support individualized treatment in the near future. A wide range of treatments for chronic wounds also influence biofilm formation. Several agents that specifically target biofilm are currently being researched. Biofilm formation has a substantial role in chronic wounds. Several diagnostic and therapeutic methods against biofilm are currently being developed.

Following confirmation of the presence of biofilms in chronic wounds, the term biofilm became a buzzword within the wound healing community. For more than a century pathogens have been successfully isolated and identified from wound specimens using techniques that were devised in the nineteenth century by Louis Pasteur and Robert Koch. Although this approach still provides valuable information with which to help diagnose acute infections and to select appropriate antibiotic therapies, it is evident that those organisms isolated from clinical specimens with the conditions normally used in diagnostic laboratories are mainly in a planktonic form that is unrepresentative of the way in which most microbial species exist naturally. Usually microbial species adhere to each other, as well as to living and non-living surfaces, where they form complex communities surrounded by collectively secreted extracellular polymeric substances (EPS). Cells within such aggregations (or biofilms) display varying physiological and metabolic properties that are distinct from those of planktonic cells, and which contribute to their persistence. There are many factors that influence healing in wounds and the discovery of biofilms in chronic wounds has provided new insight into the reasons why. Increased tolerance of biofilms to antimicrobial agents explains the limited efficacy of antimicrobial agents in chronic wounds and illustrates the need to develop new management strategies. This review aims to explain the nature of biofilms, with a view to explaining their impact on wounds.

Chronic wounds are an important problem worldwide. These wounds are characterized by a persistent inflammatory stage associated with excessive accumulation and elevated cell activity of neutrophils, suggesting that there must be a persistent stimulus that attracts and recruits neutrophils to the wound. One such stimulus might be the presence of bacterial biofilms in chronic wounds. In the present study, biopsy specimens from chronic venous leg ulcers were investigated for the detection of bacteria using peptide nucleic acid-based fluorescence in situ hybridization (PNA-FISH) and confocal laser scanning microscopy. The bacteria in the wounds were often situated in large aggregates. To obtain a measure of the cellular inflammatory response against the bacteria in the chronic wounds, the amount of neutrophils accumulated at the site of infection was evaluated through differential neutrophil counting on the tissue sections from wounds containing either Pseudomonas aeruginosa or Staphylococcus aureus. The P. aeruginosa-containing wounds had significantly higher numbers of neutrophils accumulated compared with the S. aureus-containing wounds. These results are discussed in relation to the hypothesis that the presence of P. aeruginosa biofilms in chronic wounds may be one of the main factors leading to a persistent inflammatory response and impaired wound healing.

Equine wounds have a high risk of becoming infected due to their environment. Infected wounds encompass diverse populations of microorganisms that fail to respond to antibiotic treatment, resulting in chronic non-healing wounds. In human wounds this has been attributed to the ability of bacteria to survive in a biofilm phenotypic state. Biofilms are known to delay wound healing, principally due to their recalcitrance towards antimicrobial therapies and components of the innate immune response. The presence of biofilms in equine wounds partly explains the reluctance of many lower limb wounds to heal. Non-healing limb wounds in horses are a well documented welfare and economic concern. Therefore, there is a need to develop future treatments in order to increase the healing rate, decrease the cost of treatment and reduce suffering associate with equine wounds.

ABSTRACTThis study aimed to gain clinician consensus on which signs/symptoms reported to be indicative of biofilm in chronic wounds are likely to be so. An international, two‐round eDelphi process including wound care clinicians ran from December 2023 to February 2024. Participants rated 26 items on a 9‐point Likert scale. Consensus to include: ≥ 70% of respondents rate an item 7–9, ≤ 15% rate it 1–3. Consensus to exclude: ≥ 70% of respondents rate an item 1–3, ≤ 15% rate it 7–9. Eleven items (visual indicators [a shiny, slimy, persistent layer, easily removed, returns quickly without frequent intervention]; failure to respond to antimicrobials; infection > 30 days duration; poor quality granulation tissue; stalled wound despite optimal management; persistent/prolonged inflammation; wound > 6 weeks duration; soft tissue deterioration despite antimicrobials/debridement; signs of local infection; tunnelling/undermining; presence of slough) achieved consensus to include status. To our knowledge, consensus work on this topic has not previously been performed on such a wide scale. When examined alongside similar work, clinical opinion on the matter lacks coherence. We hope that these findings will help direct us toward greater cohesiveness. The work supports a need for research to quantify the predictive abilities of signs and symptoms reported to be indicative of biofilm in chronic wounds.

Introduction: Prevention and management of biofilm in acute and chronic wounds in ICU settings is critical, as biofilm significantly impedes wound healing. Approximately 90% of all wounds are affected by biofilm. It is not feasible to eliminate biofilm using a single wound-cleaning technology. Early intervention and the combined use of multiple technologies for biofilm removal are essential to promote wound healing. Rapid and effective treatment is vital to prevent severe complications such as infections or amputations in intensive care units. Drawing on extensive knowledge of available technologies and their mechanisms of action, we adopted a multimodal approach to treat wounds with biofilm. The primary objective was to prevent and manage biofilm in both acute and chronic wounds. Methods: Five patients with infected acute and traumatic wounds—including chronic osteomyelitis tunnel wound, gunshot injuries, shrapnel wounds, surgical incisions, and fasciotomies—underwent Three-Step Multimodal Biofilm-Focused Protocol consisting of three sequential steps: Step 1: Cleansing and moistening wounds with a solution containing active pure HOCl (pH 2.5) for at least 30 minutes. Step 2: Cleansing and moistening wounds with a polyhexamethylene biguanide (PHMB) and betaine solution, left in place for 30 minutes, followed by cleaning with a debridement pad. Step 3: Application of a synergistic ionic silver (0.01%)–menthol liquid dressing with unique properties (cleansing, disinfecting, removing waste and slough, destroying biofilm). This dressing offers broad-spectrum antibacterial activity and accelerates healing. Wet pads were left in the wounds for the remainder of the day. Results / Discussion: All wounds demonstrated improvement, with the formation of new granulation tissue. Subsequent treatments included negative pressure therapy, secondary surgical closure, or skin grafting. Gunshot and shrapnel wounds healed successfully, limb amputation was avoided, and the chronic osteomyelitis tunnel wound contracted. This Three-Step Multimodal Biofilm-Focused Protocol enhanced wound healing, prevented amputations, and accelerated recovery. The method was later applied to other complex wounds in ICU patients.

Introduction: Wound healing is characterised by haemostatic, inflammatory, proliferative and remodelling phases. In the presence of comorbidities such as diabetes, healing can stall and chronic wounds may result. Infection is detrimental to these wounds and associated with poor outcomes. Wounds are contaminated with microbes and debris, and factors such as host resistance, bacterial virulence, species synergy and bioburden determine whether a wound will deteriorate to critically colonised/infected states. Biofilms are sessile microbial communities, exhibiting high-level antibiotic tolerance and resistance to host defences. Biofilm in critically colonised wounds can contribute to delayed healing. Little is known about clinical presentation and diagnosis of wound biofilms. Objective: To identify from the literature clinical signs, symptoms and biomarkers that may indicate biofilm in chronic wounds. Methods: This review will be guided by the Preferred Reporting Items for Systematic Reviews extension for Scoping Reviews (PRISMA-ScR), and the Joanna Briggs Institute Manual for Evidence Synthesis. Studies of any design in any language recruiting adult patients with venous, diabetic, pressure or mixed arterial-venous ulcers and reporting data on clinical signs/symptoms of biofilm are eligible. Searches of Medline, Embase, CINAHL, Cochrane Central, Scopus, Web of Science, Google scholar and BASE will be conducted from inception to present. Reference scanning and contact with content experts will be employed. Title/abstract screening and full text selection will be executed by two reviewers independently. Discrepancies will be resolved by discussion between reviewers or through third party intervention. Data will be extracted by a single reviewer and verified by a second. Clinical signs and symptoms data will be presented in terms of study design, setting and participant demographic data. Discussion: Understanding biofilm impact on chronic wounds is inconsistent and based largely on in vitro research. This work will consolidate clinical signs, symptoms and biomarkers of biofilm in chronic wounds reported in the literature.

To estimate the prevalence of biofilms in chronic wounds. The authors performed a systematic review of prevalence studies and meta-analysis, structured according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Articles were searched in Scopus (Elsevier), Web of Science (Clarivate), MEDLINE/PubMed (National Institutes of Health), and Embase (Elsevier) databases. Data collected included the author and year of publication, total number of lesions evaluated, number of lesions with biofilm, detected bacteria, biofilm levels, country where the research was conducted, and the methodological quality of the studies. The meta-analysis was performed using a random effects model in R software (The R Foundation for Statistical Computing). A total of 281 articles were retrieved; after applying the reading and exclusion criteria, 24 studies were included. The meta-analysis incorporated 24 studies from 12 countries, evaluating 2666 lesions with a biofilm prevalence of 68% (95% CI, 58%-79%; I² = 92%). A high prevalence was observed in Asian publications (73%; 95% CI, 62%-84%; I² = 98%), with of Staphylococcus aureus (71%; 95% CI, 51%-90%; I² = 98%) and Pseudomonas aeruginosa (65%; 95% CI, 47%-82%; I² = 98%) being the most common found in all publications. Despite the methodological heterogeneity of the studies included in this review, the findings indicate a high prevalence of biofilms in chronic wounds presented in the studies that made up the sample.

We have characterized the microbiome of infected chronic diabetic wounds (CDWs), exploring associations with antibiotic use and wound severity in a Sri Lankan cohort. Fifty CDW patients were enrolled, 38 of whom received antibiotics. Tissue biopsies were analysed by microbiome profiling, and wounds were graded using the University of Texas Wound Grading System. Biofilm presence was assessed in 20 wounds. The microbiome was largely dominated by Enterobacteriaceae, Pseudomonadaceae, Streptococcaceae, and Corynebacteriaceae. Proteobacteria levels were significantly higher in antibiotic-treated wounds (P=.019), with increased Pseudomonas abundance. Wounds were categorized as grade 1 (10), grade 2 (29), and grade 3 (11). Alpha diversity varied by wound grade (P=.015), with grade 2 wounds showing the highest diversity and grade 3 the lowest. All 20 tested wounds were biofilm-positive, and community composition varied more in antibiotic-treated wounds (P=.004). CDW microbiomes were dominated by Enterobacteriaceae and Pseudomonadaceae, with elevated Proteobacteria in antibiotic-treated wounds. Alpha diversity correlated with wound severity, peaking in grade 2 wounds. The high prevalence of biofilms in wounds underscores the need for management of CDWs that address microbial complexity.

Antiseptic agents, particularly slow-release preparations, are increasingly being used in the management of chronic wounds. One such agent, cadexomer iodine, carries iodine (0.9% weight/weight) immobilized in beads of dextrin and epichlorhydrin and has been demonstrated to be highly effective in promoting healing of exudative wounds. However, there have been no studies directly assessing the potential lack of toxicity of cadexomer iodine on human cutaneous tissues. To determine if, within a certain concentration range, cadexomer iodine is non-toxic to human cells and cutaneous tissue and to assess histologically human chronic exudative wounds that are being treated with cadexomer iodine. We examined the effects of varying concentrations of cadexomer iodine on the viability of human fibroblasts in culture (by trypan blue exclusion). The morphology, cellular proliferation capacity (measured by [3H]thymidine uptake), ability to produce alpha 1(I) procollagen chain mRNA, and cell outgrowth from neonatal foreskin explants were also evaluated in human fibroblasts after incubation with various concentrations of cadexomer iodine. Moreover, biopsies of chronic exudative wounds concurrently treated with cadexomer iodine were stained with haematoxylin and eosin or a Gram stain and evaluated microscopically. At concentrations of up to 0.45%, cadexomer iodine was found to be non-toxic to fibroblasts in vitro; there were no changes in viability, morphology, cellular proliferation, ability to produce collagen, and cell outgrowth from explants. In vivo, skin biopsies of chronic exudative wounds being treated with cadexomer iodine demonstrated no evidence of cell necrosis, displayed re-epithelialization, and revealed bacteria within the cadexomer beads. These studies demonstrate that cadexomer iodine has definite non-toxic concentration ranges for fibroblasts in vitro, which are consistent with a lack of cellular toxicity in human chronic exudative wounds treated with cadexomer iodine. Cadexomer iodine may also have the additional property of trapping microorganisms.

The purpose of this study was to evaluate the antimicrobial efficacy of thirteen bismuth thiol preparations for bactericidal activity against established biofilms formed by two bacteria isolated from human chronic wounds. Single species biofilms of a Pseudomonas aeruginosa or a methicillin-resistant Staphylococcus aureus were grown in either colony biofilm or drip-flow reactors systems. Biofilms were challenged with bismuth thiols, antibiotics or silver sulfadiazine, and log reductions were determined by plating for colony formation. Antibiotics were ineffective or inconsistent against biofilms of both bacterial species tested. None of the antibiotics tested were able to achieve >2 log reductions in both biofilm models. The 13 different bismuth thiols tested in this investigation achieved widely varying degrees of killing, even against the same micro-organism in the same biofilm model. For each micro-organism, the best bismuth thiol easily outperformed the best conventional antibiotic. Against P. aeruginosa biofilms, bismuth-2,3-dimercaptopropanol (BisBAL) at 40-80 μg ml⁻¹ achieved > 7·7 mean log reduction for the two biofilm models. Against MRSA biofilms, bismuth-1,3-propanedithiol/bismuth-2-mercaptopyridine N-oxide (BisBDT/PYR) achieved a 4·9 log reduction. Bismuth thiols are effective antimicrobial agents against biofilms formed by wound bacteria and merit further development as topical antiseptics for the suppression of biofilms in chronic wounds.

Biofilms in chronic wounds, including diabetic foot ulcers, pressure ulcers, and venous leg ulcers, pose a major challenge to wound management. Herein, we report a Janus-type antimicrobial dressing for eradication of biofilms in chronic wounds. The dressing consists of electrospun nanofiber membranes coupled with dissolvable microneedle arrays to enable effective delivery of a database-designed antimicrobial peptide to both inside and outside biofilms. This antimicrobial dressing exhibited high efficacy against a broad spectrum of resistant pathogens in vitro. Importantly, such a dressing was able to eradicate methicillin-resistant Staphylococcus aureus (MRSA) biofilms in both an ex vivo human skin wound infection model and a type II diabetic mouse wound infection model after daily treatment without applying surgical debridement. Most importantly, the dressing can also completely remove the Pseudomonas aeruginosa and MRSA, dual-species biofilm in an ex vivo human skin infection model. In addition, our computational simulations also suggested that microneedles were more effective in the delivery of peptides to the biofilms than free drugs. Our results indicate that the Janus-type antimicrobial dressings may provide an effective treatment and management of chronic wound polymicrobial infections.

The recognition of bacterial biofilm in chronic wounds is from 2008. The “Best Practice” treatment of chronic wounds seems to have developed a way of coping with biofilm without recognizing its presence with means like debridement and excessive fluid removal. The recognition of bacterial biofilm in chronic wounds may give us the opportunity to explain many of the characteristics of the chronic wound. It may explain why chronic wounds do not heal despite adequate treatment of underlying condition and give hope for future effective ways of treatment.