Cultures of diabetic foot ulcers without clinical signs of infection do not predict outcomes

An exception-reporting approach for wound swab culture: effect on post-report antibiotic initiation

A prior analysis suggested that wound swab culture (WSC) results were driving unnecessary antibiotic use in patients who were not already receiving treatment. As a quality-improvement initiative, our laboratory introduced an "exception-reporting" protocol on 1 March 2023, whereby typical wound pathogens susceptible to recommended empiric therapy (flucloxacillin/cefalexin) were not reported, and a comment was provided, stating no significant resistant organisms had been detected. Full results were available to clinicians on request. Cultures falling outside protocol criteria were reported in the standard fashion. This analysis sought to assess the effect of exception-reporting on post-report antibiotic initiation (PRAI). All community WSC results were matched to antibiotic dispensing records from October 2021 to December 2023. Sampling without treatment pre-report was termed "test and wait" (TaW). Following TaW, PRAI was identified if antibiotics were started within 5 days post-report. There were 1,819 and 764 WSCs received in the pre-change and post-change periods, respectively, where an initial TaW approach had been taken and an organism eligible for exception-reporting had been isolated. In the post-change period, 407 (53.3%) met the criteria and were exception-reported. PRAI occurred in 901 (49.5%) pre-change samples, compared to 102 (25.1%, P < 0.01) with exception-reporting. There was no detectable increase in hospitalization or repeat WSC collection in the 30 days following exception-reporting. Exception-reporting was associated with a markedly reduced proportion of patients being initiated on antibiotics following WSC where an organism had been isolated. The naming of organisms in reports appears to drive unnecessary antibiotic prescribing in many patients. These results require confirmation in other jurisdictions.

IMPORTANCE

Wound swab culture is a high-volume test performed in clinical microbiology laboratories. In this analysis, we have shown that an alternative approach to reporting positive wound swab cultures has resulted in a large reduction in post-report antibiotic initiation, suggesting that the current standard method of reporting generates considerable unnecessary antibiotic use. If these findings are replicated elsewhere, wider adoption of this reporting would represent an opportunity for many clinical microbiology laboratories to have a significant impact on community antimicrobial stewardship.

A multifunctional protein-based hydrogel with Au nanozyme-mediated self generation of H2S for diabetic wound healing

Diabetics usually suffer from chronic impaired wound healing due to facile infection, excessive inflammation, diabetic neuropathy, and peripheral vascular disease. Hence, the development of effective diabetic wound therapy remains a critical clinical challenge. Hydrogen sulfide (H2S) regulates inflammation, oxidative stress, and angiogenesis, suggesting a potential role in promoting diabetic wound healing. Herein, we propose a first example of fabricating an antibiotic-free antibacterial protein hydrogel with self-generation of H2S gas (H2S-Hydrogel) for diabetic wound healing by simply mixing bovine serum albumin‑gold nanoclusters (BSA-AuNCs) with Bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS) at room temperature within a few minutes. In this process, the amino group in BAS and the aldehyde group in THPS are crossed together by Mannich reaction. At the same time, tris(hydroxymethyl) phosphorus (trivalent phosphorus) from THPS hydrolysis could reduce disulfide bonds in BSA to sulfhydryl groups, and then the sulfhydryl group generates H2S gas under the catalysis of BSA-AuNCs. THPS in H2S-Hydrogel can destroy bacterial biofilms, while H2S can inhibit oxidative stress, promote proliferation and migration of epidermal/endothelial cells, increase angiogenesis, and thus significantly increase wound closure. It would open a new perspective on the development of effective diabetic wound dressing.

Brazilian Society of Angiology and Vascular Surgery 2023 guidelines on the diabetic foot

The diabetic foot interacts with anatomical, vascular, and neurological factors that challenge clinical practice. This study aimed to compile the primary scientific evidence based on a review of the main guidelines, in addition to articles published on the Embase, Lilacs, and PubMed platforms. The European Society of Cardiology system was used to develop recommendation classes and levels of evidence. The themes were divided into six chapters (Chapter 1 - Prevention of foot ulcers in people with diabetes; Chapter 2 - Pressure relief from foot ulcers in people with diabetes; Chapter 3 -Classifications of diabetic foot ulcers; Chapter 4 - Foot and peripheral artery disease; Chapter 5 - Infection and the diabetic foot; Chapter 6 - Charcot's neuroarthropathy). This version of the Diabetic Foot Guidelines presents essential recommendations for the prevention, diagnosis, treatment, and follow-up of patients with diabetic foot, offering an objective guide for medical practice.

Skin Pigmentation Impacts the Clinical Diagnosis of Wound Infection: Imaging of Bacterial Burden to Overcome Diagnostic Limitations

Underrepresentation of diverse skin tones in medical education and providers' implicit racial bias drives inequities in wound care, such as disproportionally poor outcomes for Black patients. Diagnostic indicators (e.g., erythema) can present differently depending on skin pigmentation. This post hoc analysis of 350 chronic wounds from a prospective 14-site clinical trial aimed to determine how the perception of clinical signs and symptoms of infection (CSS) differs by patient skin tone and if fluorescence-imaging can offer a more objective diagnostic solution. Participants were grouped by skin tone (low, medium, high) as measured by the Fitzpatrick Skin Phototype Classification (FSPC) scale. CSS and total bacterial load (TBL) were compared across FSPC groups, along with sensitivity to detect TBL >104 CFU/g using CSS alone and combined with fluorescence-imaging. Erythema was reported less often with increasing FSPC score (p = 0.05), from 13.4% (low), to 7.2% (medium), to 2.3% (high), despite comparable bacterial loads (median = 1.8 × 106 CFU/g). CSS sensitivity in the high group (2.9%) was 4.8-fold to 8.4-fold lower than the low (p = 0.003) and medium groups (p = 0.04). Fluorescence-imaging significantly improved the detection of high bacterial load in each group, peaking in the high group at 12-fold over CSS alone. These findings underscore the threat of pervasive racialized health inequities in wound care, where missed diagnosis of pathogenic bacteria and infection could delay treatment, increasing the risk of complications and poor outcomes. Fluorescence-imaging is poised to fill this gap, at least in part, serving as a more objective and equitable indicator of wound bacteria. Clinicaltrials.gov #NCT03540004 registered 16-05-2018.

An exploration of mechanisms underlying Desemzia incerta colonization resistance to methicillin-resistant Staphylococcus aureus on the skin

Colonization of human skin and nares by methicillin-resistant Staphylococcus aureus (MRSA) leads to the community spread of MRSA. This spread is exacerbated by the transfer of MRSA between humans and livestock, particularly swine. Here, we capitalized on the shared features between human and porcine skin, including shared MRSA colonization, to study novel bacterial mediators of MRSA colonization resistance. We focused on the poorly studied bacterial species Desemzia incerta, which we found to exert antimicrobial activity through a secreted product and exhibited colonization resistance against MRSA in an in vivo murine skin model. Using parallel genomic and biochemical investigation, we discovered that D. incerta secretes an antimicrobial protein. Sequential protein purification and proteomics analysis identified 24 candidate inhibitory proteins, including a promising peptidoglycan hydrolase candidate. Aided by transcriptional analysis of D. incerta and MRSA cocultures, we found that exposure to D. incerta leads to decreased MRSA biofilm production. These results emphasize the value of exploring microbial communities across a spectrum of hosts, which can lead to novel therapeutic agents as well as an increased understanding of microbial competition.IMPORTANCEMethicillin-resistant Staphylococcus aureus (MRSA) causes a significant healthcare burden and can be spread to the human population via livestock transmission. Members of the skin microbiome can prevent MRSA colonization via a poorly understood phenomenon known as colonization resistance. Here, we studied the colonization resistance of S. aureus by bacterial inhibitors previously identified from a porcine skin model. We identify a pig skin commensal, Desemzia incerta, that reduced MRSA colonization in a murine model. We employ a combination of genomic, proteomic, and transcriptomic analyses to explore the mechanisms of inhibition between D. incerta and S. aureus. We identify 24 candidate antimicrobial proteins secreted by D. incerta that could be responsible for its antimicrobial activity. We also find that exposure to D. incerta leads to decreased S. aureus biofilm formation. These findings show that the livestock transmission of MRSA can be exploited to uncover novel mechanisms of MRSA colonization resistance.

Treatment of clinically uninfected diabetic foot ulcers, with and without antibiotics

OBJECTIVE

Current guidelines do not recommend the use of antibiotics to treat clinically uninfected ulcers. However, physicians continue to prescribe antibiotics for clinically uninfected ulcers with the rationale 'better to be safe than sorry'. Yet, antibiotic resistance is increasing, side-effects are common and treatment costs are rising. Evidence is needed to identify whether antibiotic treatment for clinically uninfected ulcers can be justified or we should stop prescribing them. The aim of this study was to evaluate whether antibiotic treatment in cases of clinically uninfected ulcers improved ulcer healing compared to treatment without antibiotics.

METHOD

Consecutive patients treated in the outpatient clinic for clinically uninfected diabetic foot ulcer both in 2015 and in 2017 were retrospectively analysed. Primary outcome was ulcer healing at one year. Secondary outcomes were limb salvage, freedom from any amputation, amputation-free survival (AFS) and survival.

RESULTS

A total of 102 ulcers of 91 patients were included for final analyses. The non-antibiotics and antibiotics groups both consisted of 51 ulcers. Ulcer healing at one year was 77.3% in the non-antibiotics group and 74.7% in the antibiotics group (p=0.158). No difference was found for limb salvage (93.8% versus 95.9%, respectively; p=0.661), freedom from any amputation (85.6% versus 85.6%, respectively; p=1.000), AFS (85.4% versus 79.1%, respectively; p=0.460) or survival (89.6% versus 83.7%, respectively; p=0.426).

CONCLUSION

In this study, no benefits of antibiotic treatment over non-antibiotic treatment for clinically uninfected ulcers were identified. The findings of this study emphasise the recommendation of current guidelines to not treat clinically uninfected ulcer with antibiotics.

Post-report antibiotic initiation following community non-sterile-site microbiology results: an opportunity for labs to lead stewardship?

OBJECTIVES

Positive culture results from non-sterile sites (NSSs) are poorly predictive of clinical infection. Despite this, these results are often interpreted as an indication for antibiotics, even in patients with limited signs of infection. We sought to quantify the influence of NSS culture results on post-report antibiotic initiation (PRAI) in patients who had not been started on antibiotics pre-report.

METHODS

All community wound/skin swab and sputum cultures were matched to antibiotic dispensing records from February 2017 to July 2022. Prescribing behaviour was assessed pre- and post-report. Sampling without treatment pre-report was termed 'test-and-wait' (TaW). Following TaW, PRAI was identified if antibiotics were started within 5 days post-report.

RESULTS

There were 65 480 wound/skin swabs and 8126 sputum samples, with TaW occurring in 21 740 (35.1%) and 4185 (54.4%), respectively. Following a TaW approach PRAI occurred in 43.3% when an organism was reported, versus 10.8% (P < 0.01) for a 'no growth' report for wound/skin swabs. For the same comparison with sputum, PRAI occurred in 47.9% versus 10.8% (P < 0.01). On multivariate analysis reporting an organism remained strongly associated with PRAI.

CONCLUSIONS

Reporting an organism in those not already on antibiotics was strongly associated with PRAI. We hypothesize that for many patients TaW suggests limited evidence of infection (i.e. insufficient to justify antibiotic treatment at time of sampling), meaning positive NSS results may be driving a considerable volume of potentially unnecessary antibiotic use. Further study on this topic is required, but strategies to reduce PRAI may offer laboratories an opportunity to meaningfully impact antimicrobial stewardship efforts.

Variable staphyloxanthin production by Staphylococcus aureus drives strain-dependent effects on diabetic wound-healing outcomes

Strain-level variation in Staphylococcus aureus is a factor that contributes to disease burden and clinical outcomes in skin disorders and chronic wounds. However, the microbial mechanisms that drive these variable host responses are poorly understood. To identify mechanisms underlying strain-specific outcomes, we perform high-throughput phenotyping screens on S. aureus isolates cultured from diabetic foot ulcers. Isolates from non-healing wounds produce more staphyloxanthin, a cell membrane pigment. In murine diabetic wounds, staphyloxanthin-producing isolates delay wound closure significantly compared with staphyloxanthin-deficient isolates. Staphyloxanthin promotes resistance to oxidative stress and enhances bacterial survival in neutrophils. Comparative genomic and transcriptomic analysis of genetically similar clinical isolates with disparate staphyloxanthin phenotypes reveals a mutation in the sigma B operon, resulting in marked differences in stress response gene expression. Our work illustrates a framework to identify traits that underlie strain-level variation in disease burden and suggests more precise targets for therapeutic intervention in S. aureus-positive wounds.

An exploration of mechanisms underlying Desemzia incerta colonization resistance to methicillin-resistant Staphylococcus aureus on the skin

Colonization of human skin and nares by methicillin-resistant Staphylococcus aureus (MRSA) leads to community spread of MRSA. This spread is exacerbated by transfer of MRSA between humans and livestock, particularly swine. Here we capitalized on the shared features between human and porcine skin, including shared MRSA colonization, to study novel bacterial mediators of MRSA colonization resistance. We focused on the poorly studied bacterial species Desemzia incerta, which we found to exert antimicrobial activity through a secreted product and exhibited colonization resistance against MRSA in an in vivo murine skin model. Using parallel genomic and biochemical investigation, we discovered that D. incerta secretes an antimicrobial protein. Sequential protein purification and proteomics analysis identified 24 candidate inhibitory proteins, including a promising peptidoglycan hydrolase candidate. Aided by transcriptional analysis of D. incerta and MRSA cocultures, we found that exposure to D. incerta leads to decreased MRSA biofilm production. These results emphasize the value in exploring microbial communities across a spectrum of hosts, which can lead to novel therapeutic agents as well as increased understanding of microbial competition.

IWGDF/IDSA Guidelines on the Diagnosis and Treatment of Diabetes-related Foot Infections (IWGDF/IDSA 2023)

The International Working Group on the Diabetic Foot (IWGDF) has published evidence-based guidelines on the management and prevention of diabetes-related foot diseases since 1999. The present guideline is an update of the 2019 IWGDF guideline on the diagnosis and management of foot infections in persons with diabetes mellitus. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was used for the development of this guideline. This was structured around identifying clinically relevant questions in the P(A)ICO format, determining patient-important outcomes, systematically reviewing the evidence, assessing the certainty of the evidence, and finally moving from evidence to the recommendation. This guideline was developed for healthcare professionals involved in diabetes-related foot care to inform clinical care around patient-important outcomes. Two systematic reviews from 2019 were updated to inform this guideline, and a total of 149 studies (62 new) meeting inclusion criteria were identified from the updated search and incorporated in this guideline. Updated recommendations are derived from these systematic reviews, and best practice statements made where evidence was not available. Evidence was weighed in light of benefits and harms to arrive at a recommendation. The certainty of the evidence for some recommendations was modified in this update with a more refined application of the GRADE framework centred around patient important outcomes. This is highlighted in the rationale section of this update. A note is also made where the newly identified evidence did not alter the strength or certainty of evidence for previous recommendations. The recommendations presented here continue to cover various aspects of diagnosing soft tissue and bone infections, including the classification scheme for diagnosing infection and its severity. Guidance on how to collect microbiological samples, and how to process them to identify causative pathogens, is also outlined. Finally, we present the approach to treating foot infections in persons with diabetes, including selecting appropriate empiric and definitive antimicrobial therapy for soft tissue and bone infections; when and how to approach surgical treatment; and which adjunctive treatments may or may not affect the infectious outcomes of diabetes-related foot problems. We believe that following these recommendations will help healthcare professionals provide better care for persons with diabetes and foot infections, prevent the number of foot and limb amputations, and reduce the patient and healthcare burden of diabetes-related foot disease.

[Technical Orthopedics - Chronic Diabetic Foot Wounds]

Technical Orthopedics - Chronic Diabetic Foot Wounds Abstract: Chronic foot wounds are a very common and a growing problem. This review focuses on the treatment and the prophylaxis of diabetic foot ulcers from the perspective of technical orthopedics. Diabetic foot ulcers are of great importance for those affected, in particular because of the risk of infections and resulting amputations. With a good prophylaxis and consistent treatment, these complications can often be avoided.

'Granulitis': defining a common, biofilm-induced, hyperinflammatory wound pathology

The hard-to-heal (chronic) wound condition, now believed to be inextricably linked to the presence of microbial biofilm, has posed challenges in translating scientific understanding to clinical practice in recent decades. During this time, multiple descriptive terms of the wound pathology have been described, including critical colonisation, biofilm infection and inflammatory stasis. However, the absence of naming this disease state as a specifically identified condition that is tangible to treat has led to some confusion and delay in possible therapeutic approaches. When there is clinical uncertainty of wound status, antibiotics are too often inappropriately administered as a precaution. We therefore propose that introducing the term 'granulitis' (inflamed, unhealthy granulation tissue) could be used to identify the biofilm-induced, persistent inflammatory wound condition. This will help to raise clinician and public awareness of the condition, guide appropriate and prompt local wound hygiene, and encourage allocation of adequate resources to improve wound healing outcomes globally.

Clinical usefulness of quantifying microbial load from diabetic foot ulcers: A multicenter cohort study

AIMS

To evaluate if microbial load from diabetic foot ulcers (DFUs) can help in predicting outcomes.

METHODS

A multicenter prospective cohort study was performed in an outpatient setting (September 1, 2017-January 31, 2019) in diabetic patients with DFU.Quantitative cultures from DFU tissue biopsies at a baseline visit were obtained; high and low microbial loads were defined as ≥6logCFU/mL and <6logCFU/mL, respectively. Diagnosis of DFU infection was made and managed according to established guidelines. The outcome was evaluated at 6 month-visit as failure (persistence/new infection/amputation) or cure.

RESULTS

Out of 65 patients, 52 (80%) had long-standing DFUs (≥4 weeks), with high microbial load in 19 (29%).DFU infection (n = 24, 37%) was not associated with high microbial load in all patients but those with shorter DFU duration.Treatment failure occurred in 20/57 (35%) patients; high DFU microbial load was associated with worse outcome (n = 9/20, 45% failure rate, adjusted OR4.69; 95% CI, 1.22-18.09; p = 0.03),mainly due to the subgroup of patients with high microbial load and long-stand DFUs.

CONCLUSIONS

Since patients with high microbial load had a worse outcome, quantitative cultures from DFUs can identify patients who would benefit from antibiotic therapy.

Challenges and innovations in treating chronic and acute wound infections: from basic science to clinical practice

Acute and chronic wound infection has become a major worldwide healthcare burden leading to significantly high morbidity and mortality. The underlying mechanism of infections has been widely investigated by scientist, while standard wound management is routinely been used in general practice. However, strategies for the diagnosis and treatment of wound infections remain a great challenge due to the occurrence of biofilm colonization, delayed healing and drug resistance. In the present review, we summarize the common microorganisms found in acute and chronic wound infections and discuss the challenges from the aspects of clinical diagnosis, non-surgical methods and surgical methods. Moreover, we highlight emerging innovations in the development of antimicrobial peptides, phages, controlled drug delivery, wound dressing materials and herbal medicine, and find that sensitive diagnostics, combined treatment and skin microbiome regulation could be future directions in the treatment of wound infection.

Microbiome Characterization of Infected Diabetic Foot Ulcers in Association With Clinical Outcomes: Traditional Cultures Versus Molecular Sequencing Methods

Background

Infected diabetic foot ulcers (IDFU) are a major complication of diabetes mellitus. These potentially limb-threatening ulcers are challenging to treat due to impaired wound healing characterizing diabetic patients and the complex microbial environment of these ulcers.

Aim

To analyze the microbiome of IDFU in association with clinical outcomes.

Methods

Wound biopsies from IDFU were obtained from hospitalized patients and were analyzed using traditional microbiology cultures, 16S rRNA sequencing and metagenomic sequencing. Patients’ characteristics, culture-based results and sequencing data were analyzed in association with clinical outcomes.

Results

A total of 31 patients were enrolled. Gram-negative bacteria dominated the IDFU samples (79%, 59% and 54% of metagenomics, 16S rRNA and cultures results, respectively, p<0.001). 16S rRNA and metagenomic sequencing detected significantly more anaerobic bacteria, as compared to conventional cultures (59% and 76%, respectively vs. 26% in cultures, p=0.001). Culture-based results showed that Staphylococcus aureus was more prevalent among patients who were treated conservatively (p=0.048). In metagenomic analysis, the Bacteroides genus was more prevalent among patients who underwent amputation (p<0.001). Analysis of metagenomic-based functional data showed that antibiotic resistance genes and genes related to biofilm production and to bacterial virulent factors were more prevalent in IDFU that resulted in amputation (p<0.001).

Conclusion

Sequencing tools uncover the complex biodiversity of IDFU and emphasize the high prevalence of anaerobes and Gram-negative bacteria in these ulcers. Furthermore, sequencing results highlight possible associations among certain genera, species, and bacterial functional genes to clinical outcomes.

Complex Foot Infection Treated With Surgical Debridement and Antibiotic Loaded Calcium Sulfate-A Retrospective Cohort Study of 137 Cases

Complex foot infections involving bone and soft tissue in patients with co-morbidities such as diabetes and peripheral arterial disease (PAD) are a cause of significant hospital admission. They are associated with substantial economic costs to health services worldwide. Historically, severe foot infection has been treated with surgical debridement and prolonged courses of systemic antibiotics. Prolonged systemic antibiotic use increases the risk of drug side effects, antimicrobial resistance and Clostridium difficile infection. The purpose of this study was to investigate whether surgical debridement and implantation of antibiotic loaded calcium sulfate is effective in the resolution of foot infection and wound healing. A retrospective cohort study of 137 consecutive cases of osteomyelitis (127) or significant soft tissue infection (10) over 62 months from 02/2013 to 04/2018 was conducted following local ethical approval. All cases of infection were treated with surgical debridement and local antibiotic-loaded calcium sulfate. The primary outcomes of infection resolution, time to healing and duration of postoperative antibiotics were measured. In 137 cases, 88.3% of infections resolved. Infection was eradicated in 22 patients without postoperative systemic antibiotics. About 82.5% of wounds healed, with an average healing time of 11.3 weeks. Healing time was significantly increased for the co-morbidities of diabetes and PAD (p =< .05) and for those requiring prolonged systemic postoperative antibiotics. Conservative surgical debridement and implantation of local antibiotic impregnated calcium sulfate is safe and effective in managing complex foot infections. We advocate early surgical intervention before deeper tissue involvement to help preserve lower limb structure and function.

Evaluation of Glycologic Point-of-Care Infection Test Kit for Diabetic Foot Ulcers in Relation to Bacterial Presence: A Prospective Cohort Study

BACKGROUND

Point-of-care testing for infection might help podiatric physicians optimize management of diabetic foot ulcers (DFUs). Glycologic's proprietary GLYWD product has been developed to detect changes in a patient's immunologic/inflammatory response related to wound infection. We evaluated how bacterial presence in DFUs relates to GLYWD test outcome.

METHODS

This was a single-organization, prospective, controlled cohort study of clinical opinion versus GLYWD test result for DFU infection status and the appraisal of bacterial presence in the wounds and semiquantitative microbiology swab at weeks 0, 3, 6, 12, and 18. Spearman correlation, backward elimination linear regression, and principal components analysis were applied to determine which variables, including degree of bacterial load, are associated with a positive clinical opinion or GLYWD result for DFU infection.

RESULTS

Forty-eight patients were enrolled, and 142 complete wound appraisals were conducted; a consensus outcome between clinical opinion and GLYWD result was achieved in most (n = 122, 86%). Clinical opinion significantly correlated with a higher bacterial load (Spearman rho = 0.38; P < .01), whereas GLYWD did not (rho = -0.010; P = .91). This observation was corroborated with logistic regression analysis, in which a previous observation of both clinical opinion and GLYWD associating with wound purulence and erythema was also confirmed.

CONCLUSIONS

Podiatric physicians are guided by hallmark signs of DFU infection, such as erythema and purulence; furthermore, we found that clinical opinion of infection correlates with increased bacterial load. GLYWD test results match clinical opinion in most cases, although the results obtained with this point-of-care method suggest that the degree of bacterial presence might not necessarily mean a higher chance of inducing an immunologic/inflammatory host response to said bacteria.

The Gut-Skin Microbiota Axis and Its Role in Diabetic Wound Healing-A Review Based on Current Literature

Diabetic foot ulcers (DFU) are a growing concern worldwide as they pose complications in routine clinical practices such as diagnosis and management. Bacterial interactions on the skin surface are vital to the pathophysiology of DFU and may control delayed wound healing. The microbiota from our skin directly regulates cutaneous health and disease by interacting with the numerous cells involved in the wound healing mechanism. Commensal microbiota, in particular, interact with wound-repairing skin cells to enhance barrier regeneration. The observed microbes in DFU include Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas, and several anaerobes. Skin commensal microbes, namely S. epidermidis, can regulate the gamma delta T cells and induce Perforin-2 expression. The increased expression of Perforin-2 by skin cells destroyed S. aureus within the cells, facilitating wound healing. Possible crosstalk between the human commensal microbiome and different cell types involved in cutaneous wound healing promotes the immune response and helps to maintain the barrier function in humans. Wound healing is a highly well-coordinated, complex mechanism; it can be devastating if interrupted. Skin microbiomes are being studied in relation to the gut-skin axis along with their effects on dermatologic conditions. The gut-skin axis illustrates the connection wherein the gut can impact skin health due to its immunological and metabolic properties. The precise mechanism underlying gut-skin microbial interactions is still unidentified, but the immune and endocrine systems are likely to be involved. Next-generation sequencing and the development of bioinformatics pipelines may considerably improve the understanding of the microbiome-skin axis involved in diabetic wound healing in a much more sophisticated way. We endeavor to shed light on the importance of these pathways in the pathomechanisms of the most prevalent inflammatory conditions including the diabetes wound healing, as well as how probiotics may intervene in the gut-skin axis.

Point-of-care testing for bacterial infection in diabetic foot ulcers: a prospective cohort study

OBJECTIVE

To appraise the performance of a new point-of-care wound infection detection kit in diabetic foot ulcers (DFUs), using clinician opinion as the primary comparator. The proprietary swab-based chromatic Glycologic (Glycologic Ltd., UK) detection kit used in this study is designed to detect host response to pathogenic levels of bacteria in wounds.

METHOD

In high-risk podiatry clinics, patients with DFUs were recruited and infection detection kit test results compared with initial clinician opinion. Chi-squared tests, principal component analysis (PCA) and multiple regression analysis were performed to determine which variables were possibly associated with infection. The variables considered were patients' wound parameters, wider vascular comorbidity and demographics.

RESULTS

A total of 136 patients, providing 383 wound swabs, were included in the study. Total agreement in terms of DFU wound assessment for infection-between podiatrists' clinical opinion and Glycologic kit test result-was observed in 79% of cases (301/383). For 56 of the 349 negative infection detection kit test results (16%), podiatrists identified a 'possible' or 'definite' infection. Conversely, in 14 of the 307 cases (4.6%) where podiatrists deemed the wound 'not infected', the infection detection kit test showed a colour change. Regression analysis and PCA showed that clinical signs of wound infection, namely erythema, purulence and odour, were all significantly associated with both a positive clinical opinion and infection detection kit test result. However, in the case of the infection detection kit, a patient's number of lesions and vascular comorbidities were also significantly correlated with a positive test result.

CONCLUSION

A host response to critical pathological levels of bioburden in a wound-as detected with the infection detection kit-may partly be determined by an individual patient's (vascular) health and therefore be person-specific. Further research is indicated to determine the relationship between an infection detection kit test result and the microbiological status of the wound.

Bacteria and bioburden and healing in complex wounds: A prognostic systematic review

The wound microbiome may play an important role in the wound healing process. We conducted the first systematic prognosis review investigating whether aspects of the wound microbiome are independent prognostic factors for the healing of complex wounds. We searched Medline, Embase, CINAHL and the Cochrane Library to February 2019. We included longitudinal studies which assessed the independent association of aspects of wound microbiome with healing of complex wounds while controlling for confounding factors. Two reviewers extracted data and assessed risk of bias and certainty of evidence using the GRADE approach. We synthesised studies narratively due to the clinical and methodological heterogeneity of included studies and sparse data. We identified 28 cohorts from 21 studies with a total of 38,604 participants, including people with diabetes and foot ulcers, open surgical wounds, venous leg ulcers and pressure ulcers. Risk of bias varied from low (2 cohorts) to high (17 cohorts); the great majority of participants were in cohorts at high risk of bias. Most evidence related to the association of baseline clinical wound infection with healing. Clinical infection at baseline may be associated with less likelihood of wound healing in foot ulcers in diabetes (HR from cohort with moderate risk of bias 0.53, 95% CI 0.33 to 0.83) or slower healing in open surgical wounds (HR 0.65, 95% CI 0.51 to 0.83); evidence in other wounds is more limited. Most other associations assessed showed no clear relationship with wound healing; evidence was limited and often sparse; and we documented gaps in the evidence. There is low certainty evidence that a diagnosis of wound infection may be prognostic of poorer healing in foot ulcers in diabetes, and some moderate certainty evidence for this in open surgical wounds. Low certainty evidence means that more research could change these findings.

Impact of Rejection of Low-Quality Wound Swabs on Antimicrobial Prescribing: A Controlled Before-After Study

In this controlled before–after study, wound swabs were only processed for culture, identification, and susceptibility testing if a quality metric, determined by the Q score, was met. Rejection of low-quality wound swabs resulted in a modest decrease in reflexive antibiotic initiation while reducing laboratory workload and generating few clinician requests.

The dynamic wound microbiome

BACKGROUND

Diabetic foot ulcers (DFUs) account for the majority of all limb amputations and hospitalizations due to diabetes complications. With 30 million cases of diabetes in the USA and 500,000 new diagnoses each year, DFUs are a growing health problem. Diabetes patients with limb amputations have high postoperative mortality, a high rate of secondary amputation, prolonged inpatient hospital stays, and a high incidence of re-hospitalization. DFU-associated amputations constitute a significant burden on healthcare resources that cost more than 10 billion dollars per year. Currently, there is no way to identify wounds that will heal versus those that will become severely infected and require amputation.

MAIN BODY

Accurate identification of causative pathogens in diabetic foot ulcers is a critical component of effective treatment. Compared to traditional culture-based methods, advanced sequencing technologies provide more comprehensive and unbiased profiling on wound microbiome with a higher taxonomic resolution, as well as functional annotation such as virulence and antibiotic resistance. In this review, we summarize the latest developments in defining the microbiology of diabetic foot ulcers that have been unveiled by sequencing technologies and discuss both the future promises and current limitations of these approaches. In particular, we highlight the temporal patterns and system dynamics in the diabetic foot microbiome monitored and measured during wound progression and medical intervention, and explore the feasibility of molecular diagnostics in clinics.

CONCLUSION

Molecular tests conducted during weekly office visits to clean and examine DFUs would allow clinicians to offer personalized treatment and antibiotic therapy. Personalized wound management could reduce healthcare costs, improve quality of life for patients, and recoup lost productivity that is important not only to the patient, but also to healthcare payers and providers. These efforts could also improve antibiotic stewardship and control the rise of "superbugs" vital to global health.

The effect of continuous diffusion of oxygen treatment on cytokines, perfusion, bacterial load, and healing in patients with diabetic foot ulcers

To evaluate continuous diffusion of oxygen therapy (CDO) on cytokines, perfusion, and bacterial load in diabetic foot ulcers we evaluated 23 patients for 3 weeks. Tissues biopsies were obtained at each visit to evaluate cytokines and quantitative bacterial cultures. Perfusion was measured with hyperspectral imaging and transcutaneous oxygen. We used paired T tests to compare continuous variables and independent T tests to compare healers and nonhealers. There was an increase from baseline to week 1 in TGF-β (P = .008), TNF-α (P = .014), VEGF (P = .008), PDGF (P = .087), and IGF-1 (P = .058); baseline to week 2 in TGF-β (P = .010), VEGF (P = .051), and IL-6 (P = .031); and baseline to week 3 with TGF-β (P = .055) and IL-6 (P = .054). There was a significant increase in transcutaneous oxygen after 1 week of treatment on both medial and lateral foot (P = .086 and .025). Fifty-three percent of the patients had at least a 50% wound area reduction (healers). At baseline, there were no differences in cytokines between healers and nonhealers. However, there was an increase in CXCL8 after 1 week of treatment (P = .080) and IL-6 after 3 weeks of treatment in nonhealers (P = .099). There were no differences in quantitative cultures in healers and nonhealers.

Lyopreserved amniotic membrane is cellularly and clinically similar to cryopreserved construct for treating foot ulcers

We compared cellular viability between cryopreserved and lyopreserved amniotic membranes and clinical outcomes of the lyopreserved construct in a prospective cohort study of 40 patients with neuropathic foot ulcers. Patients received weekly application of lyopreserved membrane for 12 weeks with standard weekly debridement and offloading. We evaluated the proportion of foot ulcers that closed, time to closure, closure trajectories, and infection during therapy. We used chi-square tests for dichotomous variables and independent t-tests for continuous variables with an alpha of α = .10. Cellular viability was equivalent between cryo- and lyopreserved amniotic tissues. Clinically, 48% of subjects' wounds closed in an average of 40.0 days. Those that did not close were older (63 vs 59 years, P = .011) and larger ulcers at baseline (7.8 vs 1.6 cm² , P = .012). Significantly more patients who achieved closure reached a 50% wound area reduction in 4 weeks compared with non-closed wounds (73.7% vs 47.6%, P = .093). There was no difference in the slope of the wound closure trajectories between closed and non-closed wounds (0.124 and 0.159, P = .85), indicating the rate of closure was similar. The rate of closure was 0.60 mm/day (SD = 0.47) for wounds that closed and 0.50 mm/day (SD = 0.58) for wounds that did not close (P = .89).

Guidelines on the diagnosis and treatment of foot infection in persons with diabetes (IWGDF 2019 update)

The International Working Group on the Diabetic Foot (IWGDF) has published evidence-based guidelines on the prevention and management of diabetic foot disease since 1999. This guideline is on the diagnosis and treatment of foot infection in persons with diabetes and updates the 2015 IWGDF infection guideline. On the basis of patient, intervention, comparison, outcomes (PICOs) developed by the infection committee, in conjunction with internal and external reviewers and consultants, and on systematic reviews the committee conducted on the diagnosis of infection (new) and treatment of infection (updated from 2015), we offer 27 recommendations. These cover various aspects of diagnosing soft tissue and bone infection, including the classification scheme for diagnosing infection and its severity. Of note, we have updated this scheme for the first time since we developed it 15 years ago. We also review the microbiology of diabetic foot infections, including how to collect samples and to process them to identify causative pathogens. Finally, we discuss the approach to treating diabetic foot infections, including selecting appropriate empiric and definitive antimicrobial therapy for soft tissue and for bone infections, when and how to approach surgical treatment, and which adjunctive treatments we think are or are not useful for the infectious aspects of diabetic foot problems. For this version of the guideline, we also updated four tables and one figure from the 2016 guideline. We think that following the principles of diagnosing and treating diabetic foot infections outlined in this guideline can help clinicians to provide better care for these patients.

Association between baseline abundance of Peptoniphilus, a Gram-positive anaerobic coccus, and wound healing outcomes of DFUs

Diabetic foot ulcers (DFUs) lead to nearly 100,000 lower limb amputations annually in the United States. DFUs are colonized by complex microbial communities, and infection is one of the most common reasons for diabetes-related hospitalizations and amputations. In this study, we examined how DFU microbiomes respond to initial sharp debridement and offloading and how the initial composition associates with 4 week healing outcomes. We employed 16S rRNA next generation sequencing to perform microbial profiling on 50 samples collected from 10 patients with vascularized neuropathic DFUs. Debrided wound samples were obtained at initial visit and after one week from two DFU locations, wound bed and wound edge. Samples of the foot skin outside of the wounds were also collected for comparison. We showed that DFU wound beds are colonized by a greater number of distinct bacterial phylotypes compared to the wound edge or skin outside the wound. However, no significant microbiome diversity changes occurred at the wound sites after one week of standard care. Finally, increased initial abundance of Gram-positive anaerobic cocci (GPAC), especially Peptoniphilus (p < 0.05; n = 5 subjects), was associated with impaired healing; thus, GPAC's abundance could be a predictor of the wound-healing outcome.

Preliminary Experience with Conservative Sharp Wound Debridement by Nurses in the Outpatient Management of Diabetic Foot Ulcers: Safety, Efficacy, and Economic Analysis

BACKGROUND

Treatment of diabetes costs the United States an estimated $245 billion annually; one-third of which is related to the treatment of diabetic foot ulcers (DFUs). We present a safe, efficacious, and economically prudent model for the outpatient treatment of uncomplicated DFUs.

METHODS

77 patients (mean age = 54 years, range 31 to 83) with uncomplicated DFUs prospectively enrolled from September 2008 through February 2012. All patients received an initial sharp debridement by one of two orthopaedic foot and ankle fellowship trained surgeons. Ulcer dressings, offloading devices, and debridement procedures were standardized. Patients were evaluated every two weeks by research nurses who utilized a clinical management algorithm and performed conservative sharp wound debridement (CSWD).

RESULTS

Average time to clinical healing was 6.0 weeks. There were no complications of CSWD performed by nurses. The sensitivity for the timely identification of wound deterioration was 100%, specificity = 86.49%, PPV = 68.75% and NPV = 100% with an overall accuracy of 89.58%. The estimated cost savings in this model by having nurses perform CSWD was $223.26 per encounter, which, when extrapolated to national estimates, amounts to $1.56 billion to $2.49 billion in potential annual savings across six to ten-week treatment periods, respectively.

CONCLUSION

CSWD of DFUs by nurses in a vertically integrated multidisciplinary team is a safe, effective, and fiscally responsible clinical practice. This clinical model on a national scale could result in significant healthcare savings. Surgeons and other licensed independent practitioners would have more time for evaluating and treating more complex and operative patients; nurses would be practicing closer to the full extent of their education and training as allowed in most states.Level of Evidence: III.

Principles of STAGE Management for Diabetic Foot Ulcers Based on the Wagner and Texas Classification Systems

The current Wagner and Texas classifications of diabetic foot ulcers (DFUs) are used worldwide to assess the extent of foot lesions, but wound treatment principles based on both the classification systems are lacking. We have summarized the STAGE principles of wound treatment for clinical practice based on the Wagner and Texas classification systems. The STAGE principles refer to the principles of surgical intervention during wound treatment of DFUs and emphasize that "based on anatomical layers, the management focuses on blood supply and includes layer-by-layer incision to the infected area, maintenance of effective wound drainage, and step-by-step treatment of the wound." During treatment, microcirculation improvement and microvascular angiogenesis (A) are essential for granulation tissue formation in the bone (skeleton, S) and tendons (T) and healing of the wound with reepithelialization (E). We defined the above mentioned steps as the STAGE principles, namely, layer-by-layer incision and step-by-step management (Phase A is essential for the treatments in Phases S-T and G-E). Ulcers or gangrene formed during Phases S-T or T should be treated according to the STAGE or TAGE principles, respectively. Similar treatment principles are applied in the other phases. However, treatments at each phase are not isolated and can be performed simultaneously. The STAGE principle can be combined with the tissue, infection, moisture, and wound edge (TIME) and TIME-H chronic wound treatment principles to eliminate the shortcomings of a single principle in wound management.

Strain- and Species-Level Variation in the Microbiome of Diabetic Wounds Is Associated with Clinical Outcomes and Therapeutic Efficacy

Chronic wounds are a major complication of diabetes associated with high morbidity and health care expenditures. To investigate the role of colonizing microbiota in diabetic wound healing, clinical outcomes, and response to interventions, we conducted a longitudinal, prospective study of patients with neuropathic diabetic foot ulcers (DFU). Metagenomic shotgun sequencing revealed that strain-level variation of Staphylococcus aureus and genetic signatures of biofilm formation were associated with poor outcomes. Cultured wound isolates of S. aureus elicited differential phenotypes in mouse models that corresponded with patient outcomes, while wound "bystanders" such as Corynebacterium striatum and Alcaligenes faecalis, typically considered commensals or contaminants, also significantly impacted wound severity and healing. Antibiotic resistance genes were widespread, and debridement, rather than antibiotic treatment, significantly shifted the DFU microbiota in patients with more favorable outcomes. These findings suggest that the DFU microbiota may be a marker for clinical outcomes and response to therapeutic interventions.

The role of the microbiome in nonhealing diabetic wounds

Wound healing is a highly coordinated and complex process, and there can be devastating consequences if it is interrupted. It is believed that, in combination with host factors, microorganisms in a wound bed can not only impair wound healing but can lead to stalled, chronic wounds. It is hypothesized that the wound microbiota persists in chronic wounds as a biofilm, recalcitrant to antibiotic and mechanical intervention. Cultivation-based methods are the gold standard for identification of pathogens residing in wounds. However, these methods are biased against fastidious organisms, and do not capture the full extent of microbial diversity in chronic wounds. Thus, the link between specific microbes and impaired healing remains tenuous. This is partially because local infection and, more specifically, the formation of a biofilm, is difficult to diagnose. This has led to research efforts aimed at understanding if biofilm formation delays healing and leads to persistent and chronic infection. Circumventing challenges associated with culture-based estimations, advances in high-throughput sequencing analysis has revealed that chronic wounds are host to complex, diverse microbiomes comprising multiple species of bacteria and fungi. Here, we discuss how the use of genomic methodologies to study wound microbiomes has advanced the current understanding of infection and biofilm formation in chronic wounds.

Diabetic foot infection: Antibiotic therapy and good practice recommendations

BACKGROUND

Healthcare events related to diabetic foot disease carry a burden of morbidity, mortality and economic cost. Prompt identification of clinical infection with appropriate tissue sampling limits use of broad spectrum empirical antibiotics and improves antibiotic stewardship. Staphylococcus aureus remains the commonest infecting organism and high-dose flucloxacillin remains the empirical antibiotic of choice for antibiotic naïve patients. Barriers to microbe-specific treatment include: adequate tissue sampling, delays in culture results, drug allergies and the emergence of multidrug-resistant organisms which can complicate the choice of targeted antibiotics. Even appropriate antibiotic treatment carries a risk of adverse events including the selection of resistant organisms.

AIMS

Multidisciplinary clinical assessment of a diabetic foot infection is supported by the use of appropriate imaging modalities and deep tissue sampling, both of which are encouraged to enhance sampling accuracy. Narrow-spectrum, high dose, short duration antimicrobial therapy is ideal. Further clarity in these areas would be of benefit to clinicians involved in management of diabetic foot infections.

METHODS

A combination of literature review with expert discussion was used to generate consensus on management of diabetic foot infection, with a specific focus on empirical antimicrobial therapy.

RESULTS

Gram positive organisms represent the commonest pathogens in diabetic foot infection. However there are developing challenges in antimicrobial resistance and antibiotic availability.

DISCUSSION

Recommendations for empirical therapy, including the choice of alternative oral agents and use of outpatient antibiotics would be of benefit to those involved in diabetic foot care.

CONCLUSION

This paper provides advice on empirical antibiotic therapy that may be used as a framework for local guideline development to support clinicians in the management of diabetic foot infection.

Measuring Weight-Bearing Activities in Patients With Previous Diabetic Foot Ulcers

PURPOSE

The purpose of this article was to evaluate the accuracy of 2 physical activity monitors, monitors 1 and 2, for measuring weight-bearing activity in persons with prior diabetic foot ulcers.

DESIGN

Cross-sectional design.

INSTRUMENTS

Two recently developed monitors were used to differentiate anatomical postures such as lying, sitting, and standing upright. One monitor was designed to distinguish between duration of standing and walking and the other combines duration of standing and walking into 1 measure.

SUBJECTS AND SETTING

Thirty-one subjects were recruited; all participants had experienced a diabetic foot ulcer and completed participation in a previous cohort study. The study setting was 2 medical centers in the Midwestern United States.

METHODS

Subjects simultaneously wore the 2 monitors while performing 14 weight-bearing (ie, walking and standing) and non-weight-bearing (ie, sitting and lying) activities. The duration spent on each activity and the total number of steps taken for each walking activity were directly observed and recorded with each monitor. The accuracy of monitors 1 and 2 was assessed via direct observation as a reference standard. Paired-samples t tests were used to examine the difference in accuracy between the 2 monitors.

RESULTS

For measuring duration of activity, the accuracy of monitor 1 ranged from 73% to 100% for walking, 50% for standing, and from 42% to 100% for sitting/lying. In contrast, the accuracy of monitor 2 ranged from 98% to 100% for walking, 100% for standing, and from 97% to 100% for sitting/lying. The accuracy of monitor 1 for counting the number of steps ranged from 43% to 81%, while the accuracy of monitor 2 ranged from 91% to 99%. Monitor 2 was significantly more accurate than monitor 1 in measuring duration of standing still, slow walking, pedaling while sitting, lying on the left, and lying on the right, as well as measuring steps across different kinds of walking activities. Differences in monitor accuracy between subjects with and without foot pain and between subjects with and without foot amputation were not statistically significant.

CONCLUSION

These findings suggest that monitor 2 is a more accurate measure of weight-bearing activities than monitor 1 among patients with previous diabetic foot ulcers. Additionally, the 2 monitors differ in terms of function; monitor 2 distinguishes standing from walking, whereas monitor 1 combines standing and walking into 1 measure. We recommend monitor 2 to examine the impact of weight-bearing activity on foot ulceration in patients with diabetic neuropathy.

Biology and Biomarkers for Wound Healing

BACKGROUND

As the population grows older, the incidence and prevalence of conditions that lead to a predisposition for poor wound healing also increase. Ultimately, this increase in nonhealing wounds has led to significant morbidity and mortality with subsequent huge economic ramifications. Therefore, understanding specific molecular mechanisms underlying aberrant wound healing is of great importance. It has and will continue to be the leading pathway to the discovery of therapeutic targets, as well as diagnostic molecular biomarkers. Biomarkers may help identify and stratify subsets of nonhealing patients for whom biomarker-guided approaches may aid in healing.

METHODS

A series of literature searches were performed using Medline, PubMed, Cochrane Library, and Internet searches.

RESULTS

Currently, biomarkers are being identified using biomaterials sourced locally from human wounds and/or systemically using high-throughput "omics" modalities (genomic, proteomic, lipidomic, and metabolomic analysis). In this review, we highlight the current status of clinically applicable biomarkers and propose multiple steps in validation and implementation spectrum, including those measured in tissue specimens, for example, β-catenin and c-myc, wound fluid, matrix metalloproteinases and interleukins, swabs, wound microbiota, and serum, for example, procalcitonin and matrix metalloproteinases.

CONCLUSIONS

Identification of numerous potential biomarkers using different avenues of sample collection and molecular approaches is currently underway. A focus on simplicity and consistent implementation of these biomarkers, as well as an emphasis on efficacious follow-up therapeutics, is necessary for transition of this technology to clinically feasible point-of-care applications.

Can molecular DNA-based techniques unravel the truth about diabetic foot infections?

Diabetes foot infections are a common condition and a major causal pathway to lower extremity amputation. Identification of causative pathogens is vital in directing antimicrobial therapy. Historically, clinicians have relied upon culture-dependent techniques that are now acknowledged as both being selective for microorganisms that thrive under the physiological and nutritional constraints of the microbiology laboratory and that grossly underestimate the microbial diversity of a sample. The amplification and sequence analysis of the 16S rRNA gene has revealed a diversity of microorganisms in diabetes foot infections, extending the view of the diabetic foot microbiome. The interpretation of these findings and their relevance to clinical care remains largely unexplored. The advent of molecular methods that are culture-independent and employ massively parallel DNA sequencing technology represents a potential 'game changer'. Metagenomics and its shotgun approach to surveying all DNA within a sample (whole genome sequencing) affords the possibility to characterize not only the microbial diversity within a diabetes foot infection (i.e. 'which microorganisms are present') but the biological functions of the community such as virulence and pathogenicity (i.e. 'what are the microorganisms capable of doing'), moving the focus from single species as pathogens to groups of species. This review will examine the new molecular techniques for exploration of the microbiome of infected and uninfected diabetic foot ulcers, exploring the potential of these new technologies and postulating how they could translate to improved clinical care. Copyright © 2016 John Wiley & Sons, Ltd.

S100A8/A9 is an important host defence mediator in neuropathic foot ulcers in patients with type 2 diabetes mellitus

Chronic wounds and in particular diabetic foot ulcers (DFUs) are a growing clinical challenge, but the underlying molecular pathophysiological mechanisms are unclear. Recently, we reported reduced levels of the immunomodulating and antimicrobial S100A8/A9 in non-healing venous leg ulcers (VLUs), while another study found increased S100A8/A9 in DFUs. To clarify these apparently contradictory findings, we compared S100A8/A9 as well as an inducer, lipopolysaccharide (LPS) and selected innate immune response mediators in wound fluids from non-healing DFUs and VLUs with healing wounds. Wound fluids were collected from neuropathic DFUs (n = 6) and VLUs (n = 9) of median 2-year duration, and split-thickness skin graft donor site wounds (n = 10) by standardized method. None of the patients had ischaemic extremities or clinically infected wounds. LPS was determined by limulus amoebocyte lysate test, and S100A8/A9, granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-10 and vascular endothelial growth factor (VEGF) by immunospecific quantitative assays. LPS levels were median 8.7 (interquartile range 5.4-21.2) ng/ml in DFUs compared with 121 (22-2000) ng/ml in VLUs. S100A8/A9 was higher (p = 0.020) in DFUs [718 (634-811) µg/ml] than in VLUs [303 (252-533) µg/ml]. Neither G-CSF nor IL-10 wound fluid levels differed significantly between the chronic wound groups. VEGF levels correlated with LPS (r = 0.758, p = 0.011, n = 10) and were higher (p = 0.024) in VLU wound fluids. LPS (p < 0.0001), S100A8/A9 (p = 0.005), G-CSF (p = 0.003), IL-10 (p = 0.003) and VEGF (p = 0.005) were increased in chronic wound fluids combined compared with the sterile donor site wound fluids. The protein alterations in the wounds were not reflected in the patients' sera. Low S100A8/A9 levels may contribute to poor wound healing in colonized chronic wounds with striking difference between DFUs and VLUs.

Microbiology of diabetic foot infections: from Louis Pasteur to 'crime scene investigation'

Were he alive today, would Louis Pasteur still champion culture methods he pioneered over 150 years ago for identifying bacterial pathogens? Or, might he suggest that new molecular techniques may prove a better way forward for quickly detecting the true microbial diversity of wounds? As modern clinicians faced with treating complex patients with diabetic foot infections (DFI), should we still request venerated and familiar culture and sensitivity methods, or is it time to ask for newer molecular tests, such as 16S rRNA gene sequencing? Or, are molecular techniques as yet too experimental, non-specific and expensive for current clinical use? While molecular techniques help us to identify more microorganisms from a DFI, can they tell us 'who done it?', that is, which are the causative pathogens and which are merely colonizers? Furthermore, can molecular techniques provide clinically relevant, rapid information on the virulence of wound isolates and their antibiotic sensitivities? We herein review current knowledge on the microbiology of DFI, from standard culture methods to the current era of rapid and comprehensive 'crime scene investigation' (CSI) techniques.