The Visualization of Biofilms in Chronic Diabetic Foot Wounds

NewsBot · May 21, 2014

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The Visualization of Biofilms in Chronic Diabetic Foot Wounds Using Routine Diagnostic Microscopy Methods.
Oates A, Bowling FL, Boulton AJ, Bowler PG, Metcalf DG, McBain AJ.
J Diabetes Res. 2014;2014:153586.

Diabetic foot wounds are commonly colonised by taxonomically diverse microbial communities and may additionally be infected with specific pathogens. Since biofilms are demonstrably less susceptible to antimicrobial agents than are planktonic bacteria, and may be present in chronic wounds, there is increasing interest in their aetiological role. In the current investigation, the presence of structured microbial assemblages in chronic diabetic foot wounds is demonstrated using several visualization methods. Debridement samples, collected from the foot wounds of diabetic patients, were histologically sectioned and examined using bright-field, fluorescence, and environmental scanning electron microscopy and assessed by quantitative differential viable counting. All samples (n = 26) harboured bioburdens in excess of 5 log10 CFU/g. Microcolonies were identified in 4/4 samples by all three microscopy methods, although bright-field and fluorescence microscopy were more effective at highlighting putative biofilm morphology than ESEM. Results in this pilot study indicate that bacterial microcolonies and putative biofilm matrix can be visualized in chronic wounds using florescence microscopy and ESEM, but also using the simple Gram stain.
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NewsBot · Jan 20, 2017

The prevalence of biofilms in chronic wounds: a systematic review and meta-analysis of published data.
Malone M et al
J Wound Care. 2017 Jan 2;26(1):20-25. doi: 10.12968/jowc.2017.26.1.20.

The presence of biofilms in chronic non-healing wounds, has been identified through in vitro model and in vivo animal data. However, human chronic wound studies are under-represented and generally report low sample sizes. For this reason we sought to ascertain the prevalence of biofilms in human chronic wounds by undertaking a systematic review and meta-analysis. Our initial search identified 554 studies from the literature databases (Cochrane Library, Embase, Medline). After removal of duplicates, and those not meeting the requirements of inclusion, nine studies involving 185 chronic wounds met the inclusion criteria. Prevalence of biofilms in chronic wounds was 78.2 % (confidence interval [CI 61.6-89, p<0.002]). The results of our meta-analysis support our clinical assumptions that biofilms are ubiquitous in human chronic non-healing wounds.
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NewsBot · Jun 24, 2017

Microscopy visualisation confirms multi-species biofilms are ubiquitous in diabetic foot ulcers.
Johani K et al
Int Wound J. 2017 Jun 23. doi: 10.1111/iwj.12777.

Increasing evidence within the literature has identified the presence of biofilms in chronic wounds and proposed that they contribute to delayed wound healing. This research aimed to investigate the presence of biofilm in diabetic foot ulcers (DFUs) using microscopy and molecular approaches and define if these are predominantly mono- or multi-species. Secondary objectives were to correlate wound observations against microscopy results in ascertaining if clinical cues are useful in detecting wound biofilm. DFU tissue specimens were obtained from 65 subjects. Scanning electron microscopy (SEM) and peptide nucleic acid fluorescent in situ hybridisation (PNA-FISH) techniques with confocal laser scanning microscopy (CLSM) were used to visualise biofilm structures. Next-generation DNA sequencing was performed to explore the microbial diversity. Clinical cues that included the presence of slough, excessive exudate, a gel material on the wound bed that reforms quickly following debridement, poor granulation and pyocyanin were correlated to microscopy results. Of the 65 DFU specimens evaluated by microscopy, all were characterised as containing biofilm (100%, P < 0·001). The presence of both mono-species and multi-species biofilms within the same tissue sections were detected, even when DNA sequencing analysis of DFU specimens revealed diverse polymicrobial communities. No clinical correlations were identified to aid clinicians in identifying wound biofilm. Microscopy visualisation, when combined with molecular approaches, confirms biofilms are ubiquitous in DFUs and form either mono- or multi-species biofilms. Clinical cues to aid clinicians in detecting wound biofilm are not accurate for use in DFUs. A paradigm shift of managing DFUs needs to consider anti-biofilm strategies.
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NewsBot · Feb 28, 2018

Appraisal of Biofilm Formation in Diabetic Foot Infections by Comparing Phenotypic Methods With the Ultrastructural Analysis
Sugandhi Pugazhendh et al
JFAS; March–April, 2018Volume 57, Issue 2, Pages 309–315

Diabetic patients are more prone to the development of foot ulcers, because their underlying tissues are exposed to colonization by various pathogenic organisms. Hence, biofilm formation plays a vital role in disease progression by antibiotic resistance to the pathogen found in foot infections. The present study has demonstrated the correlation of biofilm assay with the clinical characteristics of diabetic foot infection. The clinical characteristics such as the ulcer duration, size, nature, and grade were associated with biofilm production. Our results suggest that as the size of the ulcer with poor glycemic control increased, the organism was more likely to be positive for biofilm formation. A high-degree of antibiotic resistance was exhibited by the biofilm-producing gram-positive isolates for erythromycin and gram-negative isolates for cefpodoxime. Comparisons of biofilm production using 3 different conventional methods were performed. The strong producers with the tube adherence method were able to produce biofilm using the cover slip assay method, and the weak producers in tube adherence method had difficulty in producing biofilm using the other 2 methods, indicating that the tube adherence method is the best method for assessing biofilm formation. The strong production of biofilm with the conventional method was further confirmed by scanning electron microscopy analysis, because bacteria attached as a distinct layer of biofilm. Thus, the high degree of antibiotic resistance was exhibited by biofilm producers compared with nonbiofilm producers. The tube adherence and cover slip assay were found to be the better method for biofilm evaluation.
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NewsBot · Aug 8, 2021

Biofilms in Diabetic Foot Ulcers: Impact, Risk Factors and Control Strategies
Ana C Afonso et al
Int J Mol Sci. 2021 Jul 31;22(15):8278

Diabetic foot ulcers (DFUs) are a serious complication from diabetes mellitus, with a huge economic, social and psychological impact on the patients' life. One of the main reasons why DFUs are so difficult to heal is related to the presence of biofilms. Biofilms promote wound inflammation and a remarkable lack of response to host defences/treatment options, which can lead to disease progression and chronicity. In fact, appropriate treatment for the elimination of these microbial communities can prevent the disease evolution and, in some cases, even avoid more serious outcomes, such as amputation or death. However, the detection of biofilm-associated DFUs is difficult due to the lack of methods for diagnostics in clinical settings. In this review, the current knowledge on the involvement of biofilms in DFUs is discussed, as well as how the surrounding environment influences biofilm formation and regulation, along with its clinical implications. A special focus is also given to biofilm-associated DFU diagnosis and therapeutic strategies. An overview on promising alternative therapeutics is provided and an algorithm considering biofilm detection and treatment is proposed.
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