In vivo observations of biofilm adhering to a dialkylcarbamoyl chloride-coated mesh dressing when applied to diabetes-related foot ulcers: A proof of concept study.

In this proof-of-concept study of twenty participants, we sought to determine if a DACC (Dialkylcarbamoyl chloride)-coated mesh dressing demonstrates an ability to adhere biofilm when placed on Diabetes Related Foot Ulcers (DRFUs) with chronic infection. The study also sought to determine if removal of the DACC-coated mesh dressings contributes to reducing the total number of bacteria in DRFUs, by exploring the total microbial loads, microbial community composition, and diversity. Standard of care was provided in addition to the application of DACC or DACC hydrogel every three days for a total of two weeks. Wound swabs, tissue curettage, and soiled dressings were collected pre and post-treatment. Tissue specimens obtained pre-treatment were analysed with scanning electron microscopy (SEM) and peptide nucleic acid fluorescent in situ hybridisation (PNA-FISH) with confocal laser scanning microscopy and confirmed the presence of biofilm in all DRFUs. SEM confirmed the presence of biofilms readily adhered to soiled DACC-coated mesh dressings pre- and post-treatment in all participants. Real-time quantitative polymerase chain reaction (qPCR) demonstrated the mean total microbial load of DRFUs in 20 participants did not change after two weeks of therapy (pre-treatment = 4.31 Log10 16 S copies (±0.8) versus end of treatment = 4.32 Log10 16 S copies (±0.9), P = .96, 95% CI -0.56 to 0.5). 16 S sequencing has shown the microbial composition of DACC dressings and wound swabs pre- and post-treatment remained similar (DACC; R = -.047, P = .98, Swab; R = -.04, P = .86), indicating the microbial communities originate from the ulcer. Biofilms adhere to DACC-coated mesh dressings; however, this may not reduce the total microbial load present within DRFU tissue. Wound dressings for use in hard-to-heal wounds should be used as an adjunct to a good standard of care which includes debridement and wound bed preparation.

Efficacy of a Topical Wound Agent Methanesulfonic Acid and Dimethylsulfoxide on In Vitro Biofilms.

A topical desiccating wound agent containing methanesulfonic acid, dimethylsulfoxide and amorphous silica was evaluated in three in vitro models for its efficacy against biofilms produced by Pseudomonas aeruginosa (ATCC-15442) and Staphylococcus aureus (ATCC-6538). The in vitro biofilm models used were; the MBEC Assay®, Centre for Disease Control (CDC) Biofilm Reactor® and a Semi-solid biofilm model. A 30-s exposure of a topical wound desiccating agent was used in each model. A complete eradication of viable cells was demonstrated in all models for both strains (p < 0.0001). Imaging with scanning electron microscopy (SEM) was performed where possible. All three models demonstrated complete eradication of viable cells with a 30 s application of a topical wound desiccating agent.

Efficacy of a topical concentrated surfactant gel on microbial communities in non-healing diabetic foot ulcers with chronic biofilm infections: A proof-of-concept study.

This proof-of-concept study sought to determine the effects of standard of care (SOC) and a topically applied concentrated surfactant gel (SG) on the total microbial load, community composition, and community diversity in non-healing diabetic foot ulcers (DFUs) with chronic biofilm infections. SOC was provided in addition to a topical concentrated SG, applied every 2 days for 6 weeks. Wound swabs were obtained from the base of ulcers at baseline (week 0), week 1, mid-point (week 3), and end of treatment (week 6). DNA sequencing and real-time quantitative polymerase chain reaction (qPCR) were employed to determine the total microbial load, community composition, and diversity of patient samples. Tissue specimens were obtained at baseline and scanning electron microscopy and peptide nucleic acid fluorescent in situ hybridisation with confocal laser scanning microscopy were used to confirm the presence of biofilm in all 10 DFUs with suspected chronic biofilm infections. The application of SG resulted in 7 of 10 samples achieving a reduction in mean log10 total microbial load from baseline to end of treatment (0.8 Log10 16S copies, ±0.6), and 3 of 10 samples demonstrated an increase in mean Log10 total microbial load (0.6 log10 16S copies, ±0.8) from baseline to end of treatment. Composition changes in microbial communities were driven by changes to the most dominant bacteria. Corynebacterium sp. and Streptococcus sp. frequently reduced in relative abundance in patient samples from week 0 to week 6 but did not disappear. In contrast, Staphylococcus sp., Finegoldia sp., and Fusobacterium sp., relative abundances frequently increased in patient samples from week 0 to week 6. The application of a concentrated SG resulted in varying shifts to diversity (increase or decrease) between week 0 and week 6 samples at the individual patient level. Any shifts in community diversity were independent to changes in the total microbial loads. SOC and a topical concentrated SG directly affect the microbial loads and community composition of DFUs with chronic biofilm infections.

Effect on total microbial load and community composition with two vs six-week topical Cadexomer Iodine for treating chronic biofilm infections in diabetic foot ulcers.

This study compares two vs six weeks of topical antimicrobial therapy with Cadexomer Iodine in patients with diabetic foot ulcers (DFUs) complicated by chronic biofilm infections. Patients with non-healing DFUs with suspected chronic biofilm infections were eligible for enrolment. Patients were randomised to receive either two or six weeks of treatment with topical Cadexomer Iodine. Tissue biopsies from the ulcers were obtained pre-and-post treatment and underwent DNA sequencing and real-time quantitative polymerase chain reaction (PCR) to determine the total microbial load, community composition, and diversity of bacteria. Scanning electron microscopy confirmed biofilm in all 18 ulcers with suspected chronic biofilm infections. Cadexomer Iodine resulted in 14 of 18 (78%) samples achieving a mean 0.5 log10 reduction in microbial load. Regardless of treatment duration, there was no statistical difference in the reduction of total microbial loads. No difference in the rate of wound healing in the two groups was seen at 6 weeks. Cadexomer Iodine reduces the total microbial load in DFUs with chronic biofilm infections and affects microbial community composition and diversity. All ulcers in both groups showed an initial reduction in wound size with application of Cadexomer Iodine, which might reflect its effect on biofilms.

Clinical outcomes in people with diabetes-related foot infections: Analysis from a limb preservation service infection database.

BACKGROUND: Diabetes-related foot infections are common and represent a significant clinical challenge. There are scant data about outcomes from large cohorts. The purpose of this study was to report clinical outcomes from a large cohort of people with diabetes-related foot infections. METHODS: A tertiary referral hospital limb preservation service database was established in 2018, and all new episodes of foot infections were captured prospectively using an electronic database (REDCap). People with foot infections between January 2018 and May 2023, for whom complete data were available on infection episodes, were included. Infection outcomes were compared between skin and soft tissue infections (SST-DFI) and osteomyelitis (OM) using chi-square tests. RESULTS: Data extraction identified 647 complete DFI episodes in 397 patients. The data set was divided into two cohorts identifying each infection episode and its severity as either SST-DFI (N = 326, 50%) or OM (N = 321, 50%). Most infection presentations were classified as being moderate (PEDIS 3 = 327, 51%), with 36% mild (PEDIS 2 = 239) and 13% severe (PEDIS 4 = 81). Infection resolution occurred in 69% (n = 449) of episodes with failure in 31% (n = 198). Infection failures were more common with OM than SST-DFI (OM = 140, 71% vs. SST-DFI = 58, 29%, p < 0.00001). In patients with SST-DFI a greater number of infection failures were observed in the presence of peripheral arterial disease (PAD) compared to the patients without PAD (failure occurred in 30% (31/103) of episodes with PAD and 12% (27/223) of episodes without PAD; p < 0.001). In contrast, the number of observed infection failures in OM episodes were similar in patients with and without PAD (failure occurred in 45% (57/128) of episodes with PAD and 55% (83/193) of episodes without PAD; p = 0.78). CONCLUSIONS: This study provides important epidemiological data on the risk of poor outcomes for DFI and factors associated with poor outcomes in an Australian setting. It highlights the association of PAD and treatment failure, reinforcing the need for early intervention to improve PAD in patients with DFI. Future randomised trials should assess the benefits of revascularisation and surgery in people with DFI and particularly those with OM where outcomes are worse.

A metatranscriptomic approach to explore longitudinal tissue specimens from non-healing diabetes related foot ulcers.

Cellular mechanisms and/or microbiological interactions which contribute to chronic diabetes related foot ulcers (DRFUs) were explored using serially collected tissue specimens from chronic DRFUs and control healthy foot skin. Total RNA was isolated for next-generation sequencing. We found differentially expressed genes (DEGs) and enriched hallmark gene ontology biological processes upregulated in chronic DRFUs which primarily functioned in the host immune response including: (i) Inflammatory response; (ii) TNF signalling via NFKB; (iii) IL6 JAK-STAT3 signalling; (iv) IL2 STAT5 signalling and (v) Reactive oxygen species. A temporal analysis identified RN7SL1 signal recognition protein and IGHG4 immunoglobulin protein coding genes as being the most upregulated genes after the onset of treatment. Testing relative temporal changes between healing and non-healing DRFUs identified progressive upregulation in healed wounds of CXCR5 and MS4A1 (CD20), both canonical markers of lymphocytes (follicular B cells/follicular T helper cells and B cells, respectively). Collectively, our RNA-seq data provides insights into chronic DRFU pathogenesis.

Host-microbe metatranscriptome reveals differences between acute and chronic infections in diabetes-related foot ulcers.

Virtually all diabetes-related foot ulcers (DRFUs) will become colonized by microorganisms that may increase the risk of developing an infection. The reasons why some ulcerations develop acute clinical infections (AI-DRFUs) whilst others develop chronic infection (CI-DRFUs) and the preceding host-microbe interactions in vivo remain largely unknown. Establishing that acute and chronic infections are distinct processes requires demonstrating that these are two different strategies employed by microbes when interacting with a host. In this study, dual-RNA seq was employed to differentiate the host-microbe metatranscriptome between DRFUs that had localized chronic infection or acute clinical infection. Comparison of the host metatranscriptome in AI-DRFUs relative to CI-DRFUs identified upregulated differentially expressed genes (DEGs) that functioned as regulators of vascular lymphatic inflammatory responses, T-cell signalling and olfactory receptors. Conversely, CI-DRFUs upregulated DEGs responsible for cellular homeostasis. Gene set enrichment analysis using Hallmark annotations revealed enrichment of immune and inflammatory profiles in CI-DRFUs relative to AI-DRFUs. Analysis of the microbial metatranscriptome identified the DEGs being enriched within AI-DRFUs relative to CI-DRFUs included several toxins, two-component systems, bacterial motility, secretion systems and genes encoding for energy metabolism. Functions relevant to DRFU pathology were further explored, including biofilm and bacterial pathogenesis. This identified that the expression of biofilm-associated genes was higher within CI-DRFUs compared to that of AI-DRFUs, with mucR being the most highly expressed gene. Collectively, these data provide insights into the host-microbe function in two clinically-distinct infective phenotypes that affect DRFUs. The data reveal that bacteria in acutely infected DRFUs prioritize motility over biofilm and demonstrate greater pathogenicity and mechanisms, which likely subvert host cellular and immune pathways to establish infection. Upregulation of genes for key vascular inflammatory mediators in acutely infected ulcers may contribute, in part, to the clinical picture of a red, hot, swollen foot, which differentiates an acutely infected ulcer from that of a chronic infection.

Metatranscriptome sequencing identifies Escherichia are major contributors to pathogenic functions and biofilm formation in diabetes related foot osteomyelitis.

Osteomyelitis in the feet of persons with diabetes is clinically challenging and is associated with high rates of amputation. In this study RNA-sequencing was employed to explore microbial metatranscriptomes with a view to understand the relative activity and functions of the pathogen/s responsible for diabetes foot osteomyelitis (DFO). We obtained 25 intraoperative bone specimens from persons with confirmed DFO, observing that Escherichia spp. (7%), Streptomyces spp. (7%), Staphylococcus spp. (6%), Klebsiella spp. (5%) and Proteus spp. (5%) are the most active taxa on average. Data was then subset to examine functions associated with pathogenesis (virulence and toxins), biofilm formation and antimicrobial/multi-drug resistance. Analysis revealed Escherichia spp. are the most active taxa relative to pathogenic functions with K06218 (mRNA interferase relE), K03699 (membrane damaging toxin tlyC) and K03980 (putative peptidoglycan lipid II flippase murJ), K01114 (membrane damaging toxin plc) and K19168 (toxin cptA) being the most prevalent pathogenic associated transcripts. The most abundant transcripts associated with biofilm pathways included components of the biofilm EPS matrix including glycogen synthesis, cellulose synthesis, colonic acid synthesis and flagella synthesis. We further observed enrichment of a key enzyme involved in the biosynthesis of L-rhamnose (K01710 -dTDP-glucose 4,6-dehydratase rfbB, rmlB, rffG) which was present in all but four patients with DFO.

Utilisation of the 2019 IWGDF diabetic foot infection guidelines to benchmark practice and improve the delivery of care in persons with diabetic foot infections.

AIMS: To utilise the 2019 International Working Group on the Diabetic Foot (IWGDF) - diabetic foot infection (DFI) guidelines as an audit tool for clinical practice in patients with diabetes attending a High-Risk Foot Service. METHODS: Data from 93 consecutive patients were collected over a 19-month period in patients attending a High-Risk Foot Service. The diagnosis and management of each patient in the sample were compared against the 2019 IWGDF DFI guidelines, grouped into four categories: Diagnosis, Microbiology, Treatment of soft tissue infection, and Surgical treatment and osteomyelitis. Deficits in performance were recorded using the recommendations as a benchmark standard. RESULTS: There were 109 DFI events. Nineteen (63%) of the recommendations were met, 7 (24%) were partially met, and four (13%) recommendations were not met. Fourteen of the sample had no documented requests for full blood counts. Tissue was obtained for culture in 32 (29%) of the sample. No percutaneous bone biopsies were performed. Only 13 (28%) patients had intraoperative bone specimens sent for culture and sensitivities, with no bone specimens sent for histopathology. Modification of antibiotic therapy following available culture results was low, occurring in 12 out of 63 possible occasions (19%). The duration of antibiotic regimens in PEDIS 2 infections and osteomyelitis was greater than that recommended. CONCLUSIONS: Utilising the IWGDF DFI guidelines to benchmark clinical practice is a useful tool to identify gaps in clinical performance or service delivery and may help to improve patient care.

A multiomics approach to identify host-microbe alterations associated with infection severity in diabetic foot infections: a pilot study.

Diabetic foot infections (DFIs) are a major cause of hospitalization and can lead to lower extremity amputation. In this pilot study, we used a multiomics approach to explore the host-microbe complex within DFIs. We observed minimal differences in the overall microbial composition between PEDIS infection severities, however Staphylococcus aureus and Streptococcus genera were abundant and highly active in most mild to moderate DFIs. Further, we identified the significant enrichment of several virulence factors associated with infection pathogenicity belonging to both Staphylococcus aureus and Streptococcus. In severe DFIs, patients demonstrated a greater microbial diversity and differential gene expression demonstrated the enrichment of multispecies virulence genes suggestive of a complex polymicrobial infection. The host response in patients with severe DFIs was also significantly different as compared to mild to moderate DFIs. This was attributed to the enrichment of host genes associated with inflammation, acute phase response, cell stress and broad immune-related responses, while those associated with wound healing and myogenesis were significantly depleted.

Monitoring wound progression to healing in diabetic foot ulcers using three-dimensional wound imaging.

AIM: 3D wound imaging has provided clinicians with even greater wound measurement options. No data is available to guide clinicians as to which 3D measurements may yield the most reflective marker of wound progression to healing. METHOD: A prospective pilot study was undertaken to assess the accuracy of five 3D wound measurements that best reflect metrics of interest to clinicians. Twenty-one diabetic foot ulcers were enrolled from initial ulcer presentation, through to healing. The relationship between mean wound healing measurement variables was examined using linear regression and Pearsons correlation coefficient, in addition to assessing clinician inter-rater reliability of measurements using Intra-class correlation coefficients (ICC). RESULTS: Statistical analysis demonstrated a linear healing slope for each wound measurement as having a value greater than R 0.70 and a statistical significance of p = 0.0001. This suggests that all five wound measurements are useful prognostic markers of wound progression to healing. Low variability of measurements between users indicates good inter-observer reliability. CONCLUSION: 3D wound measurements demonstrate a linear correlation between the measurement and time to healing. This suggests they could be effective prognostic markers of a wounds progression to healing and closure. It may also provide important early identification of wounds not responding to standard care. Larger studies are required to validate our results.

Analysis of proximal bone margins in diabetic foot osteomyelitis by conventional culture, DNA sequencing and microscopy.

Multiple approaches were employed to detect pathogens from bone margins associated with Diabetic Foot Osteomyelitis (DFO). Intra-operative bone specimens of 14 consecutive subjects with suspected DFO were collected over a six-month study period from Liverpool Hospital. Infected bone and a proximal bone margins presumed to be 'clean/non-infected' were collected. Bone material was subjected to conventional culture, DNA sequencing and microscopy. In total, eight of 14 (57%) proximal bone margins had no growth by conventional culture but were identified in all proximal bone specimens by DNA sequencing. Proximal margins had lower median total microbial counts than infected specimens, but these differences were not statistically significant. Pathogens identified by sequencing in infected specimens were identified in proximal margins and the microbiomes were similar (ANOSIM = 0.02, p = 0.59). Using a combination of SEM and/or PNA-FISH, we visualized the presence of microorganisms in infected bone specimens and their corresponding proximal margins of seven patients (50%) with DFO. We identify that bacteria can still reside in what seems to be proximal 'clean' margins. The significance and implications of clinical outcomes requires further analysis from a larger sample size that incorporates differences in surgical and post-operative approaches, correlating any outcomes back to culture-sequence findings.