Version Changes
Revised. Amendments from Version 1
One typographical error has been fixed in the inclusion criteria section: "any cliinical any clinical signs, symptoms and/or biomarkers." has been changed to "any clinical signs, symptoms and/or biomarkers. The sentence "Pay-per-view articles will not be included." has been removed from the exclusion criteria section. The Medline search strategy was also updated.
Abstract
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 presence 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 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.
Keywords: Chronic wound, Wound healing, Infection, Biofilm, Clinical signs and symptoms
Introduction
Wound healing occurs via a complex sequence of events which, under normal circumstances, proceed in an orderly fashion through haemostatic, inflammatory, proliferative and remodelling/maturation phases to restore cutaneous integrity and barrier function. However, in the presence of complicating factors such as diabetes or chronic venous insufficiency, the healing process can break down and the wound becomes chronic, failing to heal in a timely manner 1, 2 . There is a lack of consensus regarding the definition of chronic wounds and they have for example, been described as ‘wounds that have not proceeded through an orderly and timely reparation to produce anatomic and functional integrity after 3 months’, ‘wounds that lack a 20–40% reduction in size after 2–4 weeks of optimal treatment or when there is not complete healing after 6 weeks’, or simply as ‘wounds that fail to proceed through the normal phases of wound healing in an orderly and timely manner’ 2, 3 . Typically, these wounds include but are not limited to venous, diabetic and pressure aetiologies 4 . Chronic wounds of mixed aetiologies were estimated to have a pooled prevalence of 2.21 per 1000 population in a 2019 meta-analysis of three studies, while a second meta-analysis from the same year including nine studies estimated the pooled prevalence of chronic leg ulcers to be 1.5 per 1000 population 5 . Chronic wounds are burdensome to the individual in terms of finances and quality of life, and to healthcare systems. Unhealed diabetic foot ulcers (DFU), venous leg ulcers (VLU) and pressure ulcers (PU) cost the United Kingdom National Health Service (NHS) approximately £4 billion in 2017–2018, or an average of £6305 per patient 6, 7 .
Infection commonly affects chronic wounds and is associated with poor clinical outcomes 8 . The risk of hospitalisation for patients with a DFU is increased by a factor of 50 while the risk of lower-extremity amputation is 150 times higher if their wounds become infected. Development of infection in chronic wounds is a complex process. Multiple factors including virulence of colonising organisms, synergy between multiple microbial species, bioburden and host resistance interact with each other and determine whether a wound will progress from a non-threatening, contaminated/colonized state through to critically colonized or infected states 9 .
Bacteria can manifest in wounds as a free-floating planktonic phenotype or as a sessile biofilm phenotype 10 . Biofilms occur when microbial cells organise themselves into aggregates or communities encased in a self-produced polymeric matrix which typically attach to surfaces. Biofilms exhibit high levels of tolerance to antimicrobial agents and host defences 11 . When they form in critically colonized chronic wounds, healing stalls and the wound remains stuck in the inflammatory phase 12– 16 .
In 2017, a panel of specialists, chosen for their expertise in chronic wounds and biofilms, for their scholarly activity and publication record, issued a consensus document 17 . The document aimed to clarify the role of biofilms in clinical practice, help clinicians to recognize biofilms in chronic non-healing wounds and optimise patient management. A modified Delphi process was used to achieve consensus on a series of statements formulated to address issues in ten areas relevant to management of non-healing chronic wounds. Five-point likert scales of agreement (1 = disagree strongly – 5 = agree strongly) and ranking (1 = not important – 5 = most important) were used to score the statements. There was strong agreement (mean 4.0, standard deviation [SD] 0.82) that specific clinical signs and symptoms should be used to confirm presence of biofilm in the absence of diagnostic bedside tests. Clinical features, such as a recurring gelatinous material on the wound edge, have been proposed as surrogate markers of wound biofilm but there was weak agreement (mean 3.6, SD 1.5) that the clinical signs and symptoms that could indicate the presence of biofilm. Little is known about presentation and diagnosis of wound biofilms and knowledge of their characteristics is limited 18 . Generally, biofilms are difficult to diagnose and currently no guidelines exist to help clinicians and microbiologists in diagnosis and treatment 19 .
In addition, little quantitative work has been done with respect to clinical signs and symptoms of biofilm in chronic wounds, especially in human patients, and existing published research is mainly observational rather than incorporating more rigorous study designs 12, 17, 18, 20, 21 .
For these reasons we suspect that a rigorous systematic review with a focused research question and strict criteria with respect to eligible study design may be too exclusive and fail to answer the research question.
A scoping review methodology will therefore be employed to identify any associated clinical signs and symptoms thought to determine the presence of biofilm in chronic wounds.
The research question for the study is: what clinical signs, symptoms and biomarkers are proposed within the literature to determine the presence of biofilm in chronic wounds?
Methods
The Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement, and the Joanna Briggs Institute Manual for Evidence Synthesis will guide this work 22, 23 .
Inclusion criteria
Eligible participants will be adults (18 years +). Eligible wound aetiologies will be venous leg ulcers (VLU), diabetic foot ulcers (DFU), pressure ulcers (PU) and/or mixed arterial/venous leg ulcers (MAVLU), treated in any setting.
Databases will be searched from inception to present without limits on language. Study designs including but not limited to systematic reviews, randomized controlled trials (RCTs), controlled clinical trials, cohort studies, case series, case reports, letters to the editor with relevant data and editorials will be included. These articles must report any clinical signs, symptoms and/or biomarkers, validated or otherwise, thought to be associated with the presence of biofilm in chronic wounds.
Exclusion criteria
Patients with wounds resulting from burns, malignant fungating wounds, wounds secondary to conditions such as rheumatoid arthritis or pyoderma gangrenosum are ineligible for this study.
Search strategy
A search strategy will be developed in Medline, reviewed according to Peer Review of Electronic Search Strategies (PRESS) guidelines 24 and adapted for use in Embase, CINAHL, Cochrane Central and The Bielefeld Academic Search Engine (BASE).
Box 1. Search strategy for the Medline database.
Medline
1. “wounds and injuries”/
2. Wound healing/
3. Skin ulcer/
4. Leg ulcer/
5. Varicose ulcer/
6. Foot ulcer/
7. Diabetic foot/
8. Diabetes Mellitus, Type2/co [Complications]
9. Diabetic neuropathies/
10. Peripheral nervous system diseases/
11. Peripheral arterial disease/
12. Pressure ulcer/
13. Wound infection/
14. Debridement/
15. Re-epithelialization/
16. (chronic adj3 ulcer*).tw.
17. (skin adj3 ulcer*).tw.
18. (vascular adj3 ulcer*).tw.
19. (varicose adj3 ulcer*).tw.
20. (venous adj3 ulcer*).tw.
21. (stasis adj3 ulcer*).tw.
22. (leg adj3 ulcer*).tw.
23. (foot adj3 ulcer*).tw.
24. (diabetic adj3 ulcer*).tw.
25. (neuropathic adj3 ulcer*).tw.
26. (isch?emic adj3 ulcer*).tw.
27. (neuro-isch?emic adj3 ulcer*).tw.
28. (neuroisch?emic adj3 ulcer*).tw.
29. (pressure adj3 ulcer*).tw.
30. (decubitus adj3 ulcer*).tw.
31. (arterial adj3 ulcer*).tw.
32. (mixed adj3 ulcer*).tw.
33. (care adj3 ulcer*).tw.
34. (heal* adj3 ulcer*).tw.
35. (nonheal* adj3 ulcer*).tw.
36. (non-heal* adj3 ulcer*).tw.
37. (“non heal*” adj3 ulcer*).tw.
38. (re-epitheliali* adj3 ulcer*).tw.
39. (reepitheliali* adj3 ulcer*).tw.
40. (surface adj3 ulcer*).tw.
41. (“lower extremit*” adj3 ulcer*).tw.
42. (lower-extremit* adj3 ulcer*).tw.
43. (debrid* adj3 ulcer*).tw.
44. (manag* adj3 ulcer*).tw.
45. (bed adj3 ulcer*).tw.
46. (“hard to heal” adj3 ulcer*).tw.
47. (hard-to-heal adj3 ulcer*).tw.
48. (infect* adj3 ulcer*).tw.
49. (chronic adj3 wound*).tw.
50. (skin adj3 wound*).tw.
51. (vascular adj3 wound*).tw.
52. (varicose adj3 wound*).tw.
53. (venous adj3 wound*).tw.
54. (stasis adj3 wound*).tw.
55. (leg adj3 wound*).tw.
56. (foot adj3 wound*).tw.
57. (diabetic adj3 wound*).tw.
58. (neuropathic adj3 wound*).tw.
59. (isch?emic adj3 wound*).tw.
60. (neuro-isch?emic adj3 wound*).tw.
61. (neuroisch?emic adj3 wound*).tw.
62. (pressure adj3 wound*).tw.
63. (decubitus adj3 wound*).tw.
64. (arterial adj3 wound*).tw.
65. (mixed adj3 wound*).tw.
66. (care adj3 wound*).tw.
67. (heal* adj3 wound*).tw.
68. (nonheal* adj3 wound*).tw.
69. (non-heal* adj3 wound*).tw.
70. (“non heal*” adj3 wound*).tw.
71. (re-epitheliali* adj3 wound*).tw.
72. (reepitheliali*adj3 wound*).tw.
73. (surface adj3 wound*).tw.
74. (“lower extremit*” adj3 wound*).tw.
75. (lower-extremit* adj3 wound*).tw.
76. (debrid* adj3 wound*).tw.
77. (manag* adj3 wound*).tw.
78. (bed* adj3 wound*).tw.
79. (“hard to heal” adj3 wound*).tw.
80. (hard-to-heal adj3 wound*).tw.
81. (infect* adj3 wound*).tw.
82. (diabetic adj3 foot).tw.
83. (diabetic adj3 feet).tw.
84. (pressure adj3 sore*).tw.
85. bedsore*.tw.
86. “bed sore*”.tw.
87. bed-sore*.tw.
88. or/1-87
89. (“mixed etiolog*” adj3 ulcer*).tw.
90. (“mixed aetiolog*” adj3 ulcer*).tw.
91. (“mixed etiolog*” adj3 wound*).tw.
92. (“mixed aetiolog*” adj3 wound*).tw.
93. or/89-92
94. 88 or 93
95. Exp Biofilms/
96. biofilm*.tw.
97. “EPS matrix”.tw.
98. “EPS matrices”.tw.
99. “extracellular polymeric substance*”.tw.
100. or/95-99
101. 94 AND 100
102. Exp Animals/ NOT (Humans/ and exp Animals/)
103. 101 NOT 102
Reference scanning. Reference lists of included articles will be scanned to locate subsequent, potentially relevant articles.
Content experts and organisations. Content experts and relevant organisations will be consulted to obtain information about unpublished or ongoing studies and where applicable, to request access to known but unavailable sources of evidence.
Search results will be exported to EndNote X9 TM for storage and to RAYYAN 25 for screening against eligibility criteria.
Evidence screening and selection
Level 1 screening (title and abstract screening). Pairs of researchers will independently screen titles and abstracts for inclusion according to the pre-determined eligibility criteria. A single failed eligibility criterion will be considered sufficient to exclude a study from this review. Discrepancies will be resolved by discussion between researchers in a pair. In cases where disagreements cannot be resolved, a final decision on the discrepancy will be made by a third party.
The screening process will be pilot tested on a random sample of 50 titles and abstracts.
Level 2 screening (full text screening). Pairs of researchers will independently screen all located full text articles for inclusion into this review according to eligibility criteria. A single failed eligibility criterion will be considered sufficient to exclude a study from this review. Discrepancies will be resolved by discussion between researchers in a pair. In cases where disagreements cannot be resolved, a final decision on the discrepancy will be made by a third party.
This level of the screening process will be pilot tested on a random sample of 10 articles if available.
A chart of the screening and selection process detailing the flow of studies from the search to data extraction and including duplicate removal will be presented with the findings.
An appendix of excluded full -text articles will also be included along with reasons for exclusion.
Data extraction
A data extraction form will be developed a priori in Microsoft Excel (2016). The form will capture the following data:
-
-
Study data including authorship, year of publication, article type/study design, country of origin, setting and study objective.
-
-
Participant data including sample size, age, gender and wound aetiology.
-
-
Study concept data i.e. reported clinical signs, symptoms and biomarkers of biofilm in chronic wounds.
Data will be extracted by a single researcher and verified by a second.
Critical appraisal/risk of bias assessment
The aim of this review is to collate a comprehensive list of signs, symptoms and biomarkers used to indicate presence of biofilm in chronic wounds regardless of their level of refinement. Relevant data may be found in articles that span the evidence hierarchy and range from systematic reviews to opinion/editorial articles 21 . For these reasons, risk of bias assessment of included articles will not be necessary.
Data analysis, summary and presentation
Extracted data will be tabulated. Concept data will be presented in terms of country of origin, setting, study design, and in terms of participant data i.e. sample size, wound aetiology, age and gender. Data will be analysed with SPSS statistical package version 26. Demographic data will be presented descriptively in terms of mean and standard deviation or median and range.
Discussion
Little work regarding biofilms’ impact on chronic wounds involving human subjects has been done and much of our clinical understanding is based on in vitro work. Clinician’s knowledge of research data and of the importance of biofilms in the management of non-healing chronic wounds is inconsistent 17 . This review will for the first time, consolidate those signs, symptoms and biomarkers of biofilm in chronic wounds reported in the literature into one document which may serve to open an avenue for future clinical research in this area.
Dissemination
The findings of this scoping review will be published in a peer-reviewed medical journal.
The research team will also regularly update and disseminate project findings to key stakeholders, research colleagues, patient representatives and knowledge users.
Study status
The review has not yet initiated.
Data availability
No data are associated with this article.
Funding Statement
This project was supported by the Health Research Board (HRB) Collaborative Doctoral Awards (CDA) programme; and the Irish Research Council (IRC) [GOIPG/2020/535].
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
[version 2; peer review: 2 approved, 1 approved with reservations]
References
- 1. Han G, Ceilley R: Chronic Wound Healing: A Review of Current Management and Treatments. Adv Ther. 2017;34(3):599–610. 10.1007/s12325-017-0478-y [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2. Frykberg RG, Banks J: Challenges in the Treatment of Chronic Wounds. Adv Wound Care (New Rochelle). 2015;4(9):560–582. 10.1089/wound.2015.0635 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Kyaw BM, Järbrink K, Martinengo L, et al. : Need for Improved Definition of "Chronic Wounds" in Clinical Studies. Acta Derm Venereol. 2018;98(1):157–158. 10.2340/00015555-2786 [DOI] [PubMed] [Google Scholar]
- 4. Chronic wounds. [cited 2021 15 April]. Reference Source [Google Scholar]
- 5. Martinengo L, Olsson M, Bajpai R, et al. : Prevalence of chronic wounds in the general population: systematic review and meta-analysis of observational studies. Ann Epidemiol. 2019;29:8–15. 10.1016/j.annepidem.2018.10.005 [DOI] [PubMed] [Google Scholar]
- 6. Kapp S, Santamaria N: The financial and quality-of-life cost to patients living with a chronic wound in the community. Int Wound J. 2017;14(6):1108–1119. 10.1111/iwj.12767 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7. Guest JF, Fuller GW, Vowden P: Cohort study evaluating the burden of wounds to the UK's National Health Service in 2017/2018: update from 2012/2013. BMJ Open. 2020;10(12):e045253. 10.1136/bmjopen-2020-045253 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Siddiqui AR, Bernstein JM: Chronic wound infection: facts and controversies. Clin Dermatol. 2010;28(5):519–26. 10.1016/j.clindermatol.2010.03.009 [DOI] [PubMed] [Google Scholar]
- 9. Ivory J, Gethin G, McIntosh C: Antimicrobial Dressings for treating local infection in patients with diabetic foot ulcers. The Diabetic Foot Journal. 2018;21(3):155–159. Reference Source [Google Scholar]
- 10. Percival SL, McCarty SM, Lipsky B: Biofilms and Wounds: An Overview of the Evidence. Adv Wound Care (New Rochelle). 2015;4(7):373–381. 10.1089/wound.2014.0557 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11. Waters EM, Rowe SE, O'Gara JP, et al. : Convergence of Staphylococcus aureus Persister and Biofilm Research: Can Biofilms Be Defined as Communities of Adherent Persister Cells? PLoS Pathog. 2016;12(12):e1006012. 10.1371/journal.ppat.1006012 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12. Metcalf DG, Bowler PG, Hurlow J: A clinical algorithm for wound biofilm identification. J Wound Care. 2014;23(3):137–8, 140,– 2. 10.12968/jowc.2014.23.3.137 [DOI] [PubMed] [Google Scholar]
- 13. Oates A, Bowling FL, Boulton AJM, et al. : The visualization of biofilms in chronic diabetic foot wounds using routine diagnostic microscopy methods. J Diabetes Res. 2014;2014:153586. 10.1155/2014/153586 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14. Bjarnsholt T, Alhede M, Alhede M, et al. : The in vivo biofilm. Trends Microbiol. 2013;21(9):466–74. 10.1016/j.tim.2013.06.002 [DOI] [PubMed] [Google Scholar]
- 15. Rahim K, Saleha S, Zhu X, et al. : Bacterial Contribution in Chronicity of Wounds. Microb Ecol. 2017;73(3):710–721. 10.1007/s00248-016-0867-9 [DOI] [PubMed] [Google Scholar]
- 16. Alves PJ, Barreto RT, Barrois BM, et al. : Update on the role of antiseptics in the management of chronic wounds with critical colonisation and/or biofilm. Int Wound J. 2021;18(3):342–358. 10.1111/iwj.13537 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17. Schultz G, Bjarnsholt T, James GA, et al. : Consensus guidelines for the identification and treatment of biofilms in chronic nonhealing wounds. Wound Repair Regen. 2017;25(5):744–757. 10.1111/wrr.12590 [DOI] [PubMed] [Google Scholar]
- 18. Hurlow J, Bowler PG: Clinical experience with wound biofilm and management: a case series. Ostomy Wound Manage. 2009;55(4):38–49. [PubMed] [Google Scholar]
- 19. Høiby N, Bjarnsholt T, Moser C, et al. : ESCMID guideline for the diagnosis and treatment of biofilm infections 2014. Clin Microbiol Infect. 2015;21 Suppl 1:S1–25. 10.1016/j.cmi.2014.10.024 [DOI] [PubMed] [Google Scholar]
- 20. Leaper DJ, Schultz G, Carville K, et al. : Extending the TIME concept: what have we learned in the past 10 years?(*). Int Wound J. 2012;9 Suppl 2(Suppl 2):1–19. 10.1111/j.1742-481X.2012.01097.x [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21. Murad MH, Asi N, Alsawas M, et al. : New evidence pyramid. Evid Based Med. 2016;21(4):125–7. 10.1136/ebmed-2016-110401 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22. Tricco AC, Lillie E, Zarin W, et al. : PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation. Ann Intern Med. 2018;169(7):467–473. 10.7326/M18-0850 [DOI] [PubMed] [Google Scholar]
- 23. Peters MDJ, Godfrey C, McInerney P, et al. : Scoping Reviews.In Manual for Evidence Synthesis. E. Aromataris and Z. Munn, Editors. JBI,2020. 10.46658/JBIMES-20-12 [DOI] [Google Scholar]
- 24. McGowan J, Sampson M, Salzwedel DM, et al. : Peer Review of Electronic Search Strategies: 2015 Guideline Statement. J Clin Epidemiol. 2016;75:40–6. 10.1016/j.jclinepi.2016.01.021 [DOI] [PubMed] [Google Scholar]
- 25. Ouzzani M, Hammady H, Fedorowicz Z, et al. : Rayyan-a web and mobile app for systematic reviews. Syst Rev. 2016;5(1):210. 10.1186/s13643-016-0384-4 [DOI] [PMC free article] [PubMed] [Google Scholar]