Evidence of differential microbiomes in healing versus non-healing diabetic foot ulcers prior to and following foot salvage therapy

Microbial Influences on Calcium-Phosphorus Homeostasis and Metabolic Bone Diseases: A Bidirectional Mendelian Randomisation Study on the Gut-Bone Axis

Observational studies have shown that the gut microbiota (GM) is associated with bone diseases, particularly calcium-phosphorus metabolic bone diseases, demonstrating the existence of a gut-bone axis. However, whether these associations are causal effects remains to be determined. This study employed bidirectional two-sample Mendelian randomisation (MR) using summary data from Genome-Wide Association Studies (GWAS) of 211 gut microbial taxa and six metabolic bone diseases (osteoporosis, Osteopenia, osteonecrosis, osteomyelitis, hypoparathyroidism and hyperparathyroidism) to explore causal relationships and their directionality. Comprehensive sensitivity analyses were conducted to ensure the robustness of the results, and a false discovery rate-corrected pFDR of < 0.05 was used as a threshold to support strong associations. Additionally, co-localisation analysis was conducted to consolidate the findings. We identified 35 causal relationships between GM and metabolic bone diseases, with 17 exhibiting positive and 18 negative correlations. Furthermore, reverse MR analysis indicated that osteomyelitis was associated with elevated abundance of two GMs (pFDR < 0.05, PP.H4 < 75%). No evidence of horizontal pleiotropy or heterogeneity was observed, and co-localisation analysis further strengthened the evidence for these causal relationships. The study underscores the critical role of GM in influencing bone health through the gut-bone axis, paving the way for future therapeutic interventions targeting the gut-bone axis and offering new directions for research in bone metabolism and diseases.

Wound management, healing, and early prosthetic rehabilitation: Part 1 - A scoping review of healing and non-healing definitions

BACKGROUND

Following lower limb amputation, timely prosthetic fitting enhances mobility and quality of life. However, inconsistent definitions of surgical site healing complicate prosthesis readiness assessment and highlight the need for objective wound management measures.

OBJECTIVE

This review aimed to compile definitions of healing and non-healing provided in the literature investigating biomarkers of healing of the tissues and structures found in the residual limbs of adults with amputation.

METHODOLOGY

A scoping review was conducted following JBI and PRISMA-ScR guidance. Searches using "biomarkers," "wound healing," and "amputation" were performed on May 6, 2023, on Web of Science, Ovid MEDLINE, Ovid Embase, Scopus, Cochrane, PubMed, and CINAHL databases. Inclusion criteria were: 1) References to biomarkers and healing; 2) Residuum tissue healing; 3) Clear methodology with ethical approval; 4) Published from 2017 onwards. Articles were assessed for quality (QualSyst tool) and evidence level (JBI system).

FINDINGS

Of 3,306 articles screened, 219 met the inclusion criteria and are reviewed in this article, with 77% rated strong quality. 43% of all included sources did not define healing, while the remainder used specific criteria including epithelialization (14%), wound size reduction (28%), gradings scales (3%), scarring (1%), absence of wound complications (2%), hydroxyproline levels (0.5%), no amputation (0.5%), or neovascularization (0.5%). 84% of included sources did not provide definitions of non-healing. Studies defining non-healing used criteria like wound complications (4%), the need for operative interventions (4%), or lack of wound size reduction (1%). For 10% of included sources, healing and non-healing definitions were considered not applicable given the research content. Total percentages exceed 100% for both healing and non-healing definitions because some sources used two definition classifications, such as epithelialization and wound size reduction. The findings indicate a lack of standardized definitions irrespective of study type.

CONCLUSION

This review reveals significant gaps in current definitions of healing and non-healing, often based on superficial assessments that overlook deeper tissue healing and mechanical properties essential for prosthesis use. It emphasizes the need for comprehensive definitions incorporating biomarkers and psychosocial factors to improve wound management and post-amputation recovery.

Which biomarkers predict hard-to-heal diabetic foot ulcers? A scoping review

Diabetic foot ulcers (DFUs) often develop into hard-to-heal wounds due to complex factors. Several biomarkers capable of identifying those at risk of delayed wound healing have been reported. Controlling or targeting these biomarkers could prevent the progression of DFUs into hard-to-heal wounds. This scoping review aimed to identify the key biomarkers that can predict hard-to-heal DFUs. Studies that reported biomarkers related to hard-to-heal DFUs, from 1980 to 2023, were mapped. Studies were collected from the following databases: MEDLINE, CINAHL, EMBASE, and ICHUSHI (Japana Centra Revuo Medicina), search terms included "diabetic," "ulcer," "non-healing," and "biomarker." A total of 808 articles were mapped, and 14 (10 human and 4 animal studies) were included in this review. The ulcer characteristics in the clinical studies varied. Most studies focused on either infected wounds or neuropathic wounds, and patients with ischemia were usually excluded. Among the reported biomarkers for the prediction of hard-to-heal DFUs, the pro-inflammatory cytokine CXCL-6 in wound fluid from non-infected and non-ischemic wounds had the highest prediction accuracy (area under the curve: 0.965; sensitivity: 87.27%; specificity: 95.56%). CXCL-6 levels could be a useful predictive biomarker for hard-to-heal DFUs. However, CXCL6, a chemoattractant for neutrophilic granulocytes, elicits its chemotactic effects by combining with the chemokine receptors CXCR1 and CXCR2, and is involved in several diseases. Therefore, it's difficult to use CXCL6 as a prevention or treatment target. Targetable specific biomarkers for hard-to-heal DFUs need to be determined.

Community assembly of the human piercing microbiome

Predicting how biological communities respond to disturbance requires understanding the forces that govern their assembly. We propose using human skin piercings as a model system for studying community assembly after rapid environmental change. Local skin sterilization provides a 'clean slate' within the novel ecological niche created by the piercing. Stochastic assembly processes can dominate skin microbiomes due to the influence of environmental exposure on local dispersal, but deterministic processes might play a greater role within occluded skin piercings if piercing habitats impose strong selection pressures on colonizing species. Here we explore the human ear-piercing microbiome and demonstrate that community assembly is predominantly stochastic but becomes significantly more deterministic with time, producing increasingly diverse and ecologically complex communities. We also observed changes in two dominant and medically relevant antagonists (Cutibacterium acnes and Staphylococcus epidermidis), consistent with competitive exclusion induced by a transition from sebaceous to moist environments. By exploiting this common yet uniquely human practice, we show that skin piercings are not just culturally significant but also represent ecosystem engineering on the human body. The novel habitats and communities that skin piercings produce may provide general insights into biological responses to environmental disturbances with implications for both ecosystem and human health.

Prognostic factors for delayed healing of complex wounds in adults: A scoping review

Complex or hard-to-heal wounds continue to be a challenge because of the negative impact they have on patients, caregivers, and all the associated costs. This study aimed to identify prognostic factors for the delayed healing of complex wounds. Five databases and grey literature were the sources used to research adults with pressure ulcers/injuries, venous leg ulcers, critical limb-threatening ischaemia, or diabetic foot ulcers and report the prognostic factors for delayed healing in all care settings. In the last 5 years, a total of 42 original peer-reviewed articles were deemed eligible for this scoping review that followed the JBI recommendations and checklist PRISMA-ScR. The most frequent prognostic factors found with statistical significance coinciding with various wound aetiologies were: gender (male), renal disease, diabetes, peripheral arterial disease, the decline in activities of daily life, wound duration, wound area, wound location, high-stage WIfI classification, gangrene, infection, previous ulcers, and low ankle brachial index. It will be essential to apply critical appraisal tools and assessment risk of bias to the included studies, making it possible to make recommendations for clinical practice and build prognostic models. Future studies are recommended because the potential for healing through identification of prognostic factors can be determined, thus allowing an appropriate therapeutic plan to be developed.

Understanding the impact of spinal cord injury on the microbiota of healthy skin and pressure injuries

Pressure injuries (PI) are a common issue among individuals with spinal cord injury (SCI), especially in the sitting areas of the body. Considering the risk of infections occurring to PI during the wound healing process, the skin microbiome is likely to be a source of bacteria. We investigated the relationship between skin and PI microbiomes, and assessed any correlation with clinically relevant outcomes related to PI. Samples were isolated from SCI patients undergoing reconstructive surgery of PI, severity grades III and IV. DNA samples from skin and PI were analysed using 16S rRNA gene sequencing. Our results showed disparities in microbiome composition between skin and PI. The skin had lower diversity, while PI showed increased bacterial homogeneity as the severity grade progressed. The skin bacterial composition varied based on its location, influenced by Cutibacterium. Compositional differences were identified between PI grades III and IV, with clusters of bacteria colonizing PI, characterized by Pseudomonas, Proteus and Peptoniphilus. The skin and PI microbiomes were not affected by the level of the SCI. Our study highlights the differences in the microbiome of skin and PI in SCI patients. These findings could be used to target specific bacteria for PI treatment in clinical practice.

Multi-Instrumental Analysis Toward Exploring the Diabetic Foot Infection Microbiota

The polymicrobial nature of diabetic foot infection (DFI) makes accurate identification of the DFI microbiota, including rapid detection of drug resistance, challenging. Therefore, the main objective of this study was to apply matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) technique accompanied by multiply culture conditions to determine the microbial patterns of DFIs, as well as to assess the occurrence of drug resistance among Gram-negative bacterial isolates considered a significant cause of the multidrug resistance spread. Furthermore, the results were compared with those obtained using molecular techniques (16S rDNA sequencing, multiplex PCR targeting drug resistance genes) and conventional antibiotic resistance detection methods (Etest strips). The applied MALDI-based method revealed that, by far, most of the infections were polymicrobial (97%) and involved many Gram-positive and -negative bacterial species-19 genera and 16 families in total, mostly Enterobacteriaceae (24.3%), Staphylococcaceae (20.7%), and Enterococcaceae (19.8%). MALDI drug-resistance assay was characterized by higher rate of extended-spectrum beta-lactamases (ESBLs) and carbapenemases producers compared to the reference methods (respectively 31% and 10% compared to 21% and 2%) and revealed that both the incidence of drug resistance and the species composition of DFI were dependent on the antibiotic therapy used. MALDI approach included antibiotic resistance assay and multiply culture conditions provides microbial identification at the level of DNA sequencing, allow isolation of both common (eg. Enterococcus faecalis) and rare (such as Myroides odoratimimus) bacterial species, and is effective in detecting antibiotic-resistance, especially those of particular interest-ESBLs and carbapenemases.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Colonizing microbiota is associated with clinical outcomes in diabetic wound healing

With the development of society and the improvement of life quality, more than 500 million people are affected by diabetes. More than 10 % of people with diabetes will suffer from diabetic wounds, and 80 % of diabetic wounds will reoccur, so the development of new diabetic wound treatments is of great importance. The development of skin microbe research technology has gradually drawn people's attention to the complex relationship between microbes and diabetic wounds. Many studies have shown that skin microbes are associated with the outcome of diabetic wounds and can even be used as one of the indicators of wound prognosis. Skin microbes have also been found to have the potential to treat diabetic wounds. The wound colonization of different bacteria can exert opposing therapeutic effects. It is necessary to fully understand the skin microbes in diabetic wounds, which can provide valuable guidance for clinical diabetic wound treatment.

The Skin Microbiome: Current Landscape and Future Opportunities

Our skin is the largest organ of the body, serving as an important barrier against the harsh extrinsic environment. Alongside preventing desiccation, chemical damage and hypothermia, this barrier protects the body from invading pathogens through a sophisticated innate immune response and co-adapted consortium of commensal microorganisms, collectively termed the microbiota. These microorganisms inhabit distinct biogeographical regions dictated by skin physiology. Thus, it follows that perturbations to normal skin homeostasis, as occurs with ageing, diabetes and skin disease, can cause microbial dysbiosis and increase infection risk. In this review, we discuss emerging concepts in skin microbiome research, highlighting pertinent links between skin ageing, the microbiome and cutaneous repair. Moreover, we address gaps in current knowledge and highlight key areas requiring further exploration. Future advances in this field could revolutionise the way we treat microbial dysbiosis associated with skin ageing and other pathologies.

Role of wound microbiome, strategies of microbiota delivery system and clinical management

Delayed wound healing is one of the most global public health threats affecting nearly 100 million people each year, particularly the chronic wounds. Many confounding factors such as aging, diabetic disease, medication, peripheral neuropathy, immunocompromises or arterial and venous insufficiency hyperglycaemia are considered to inhibit wound healing. Therapeutic approaches for slow wound healing include anti-infection, debridement and the use of various wound dressings. However, the current clinical outcomes are still unsatisfied. In this review, we discuss the role of skin and wound commensal microbiota in the different healing stages, including inflammation, cell proliferation, re-epithelialization and remodelling phase, followed by multiple immune cell responses to commensal microbiota. Current clinical management in treating surgical wounds and chronic wounds was also reviewed together with potential controlled delivery systems which may be utilized in the future for the topical administration of probiotics and microbiomes. This review aims to introduce advances, novel strategies, and pioneer ideas in regulating the wound microbiome and the design of controlled delivery systems.

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.

Evaluation of Polymerase Chain Reaction in the Identification and Quantification of Clinically Relevant Bacterial Species in Lower Extremity Wound Infections

Identification of bacteria by polymerase chain reaction (PCR) is known to be more sensitive than culture, which brings to question the clinical applicability of the results. In this study, we evaluate the ability of PCR to detect clinically relevant bacterial species in lower extremity wound infections requiring operative debridement, as well as the quantitative change in biodiversity and bacterial load reflected by PCR during the course of treatment. Thirty-four infected lower extremity were examined by analysis of 16S ribosomal RNA subunit and by culture. McNemar's test was used to measure the concordance of clinically relevant bacterial species identified by PCR compared to culture during each debridement. Change in wound biodiversity from initial presentation to final closure was evaluated by Wilcoxon signed-rank test. Kaplan-Meier survival curve was used to characterize change in measured bacterial load over the course of operative debridement. A total of 15 and 12 clinically relevant bacterial species were identified by PCR and culture, respectively. The most common bacterial species identified were Coagulase-negative Staphylococcus, Staphylococcus aureus, and Enterococcus spp. PCR was less likely to detect Enterococcus spp. on initial debridement and Coagulase-negative Staphylococcus on closure in this study population. A significant decrease in mean number of clinically relevant species detected from initial debridement to closure was reflected by culture (p = .0188) but not by PCR (p = .1848). Both PCR (p = .0128) and culture (p = .0001) depicted significant reduction in mean bacterial load from initial debridement to closure. PCR is able to identify common clinically relevant bacterial species in lower extremity surgical wound infections. PCR displays increased sensitivity compared to culture with relation to detection of biodiversity, rather than bacterial load. Molecular diagnostics and conventional culture may serve a joint purpose to assist with rendering clinical judgment in complex wound infections.

Emerging Diabetic Foot Ulcer Microbiome Analysis Using Cutting Edge Technologies

One of the most prevalent complications of diabetes mellitus are diabetic foot ulcers (DFU). Diabetic foot ulcers represent a complex condition placing individuals at-risk for major lower extremity amputations and are an independent predictor of patient mortality. DFU heal poorly when standard of care therapy is applied. In fact, wound healing occurs only approximately 30% within 12 weeks and only 45% regardless of time when standard of care is utilized. Similarly, diabetic foot infections occur in half of all DFU and conventional microbiologic cultures can take several days to process before a result is known. DFU represent a significant challenge in this regard because DFU often demonstrate polymicrobial growth, become resistant to preferred antibiotic therapy, and do not inform providers about long-term prognosis. In addition, conventional culture yields may be affected by the timing of antibiotic administration and collection of tissue for analysis. This may lead to suboptimal antibiotic administration or debilitating amputations. The microbiome of DFU is a new frontier to better understand the interactions between host organisms and pathogenic ones. Newer molecular techniques are readily available to assist in analyzing the constituency of the microbiome of DFU. These emerging techniques have already been used to study the microbiome of DFU and have clinical implications that may alter standard of care practice in the near future. Here emerging molecular techniques that can provide clinicians with rapid DFU-related-information and help prognosticate outcomes in this vulnerable patient population are presented.

Bioactive Antimicrobial Peptides as Therapeutic Agents for Infected Diabetic Foot Ulcers

Diabetic foot ulcer (DFU) is a devastating complication, affecting around 15% of diabetic patients and representing a leading cause of non-traumatic amputations. Notably, the risk of mixed bacterial–fungal infection is elevated and highly associated with wound necrosis and poor clinical outcomes. However, it is often underestimated in the literature. Therefore, polymicrobial infection control must be considered for effective management of DFU. It is noteworthy that antimicrobial resistance is constantly rising overtime, therefore increasing the need for new alternatives to antibiotics and antifungals. Antimicrobial peptides (AMPs) are endogenous peptides that are naturally abundant in several organisms, such as bacteria, amphibians and mammals, particularly in the skin. These molecules have shown broad-spectrum antimicrobial activity and some of them even have wound-healing activity, establishing themselves as ideal candidates for treating multi-kingdom infected wounds. Furthermore, the role of AMPs with antifungal activity in wound management is poorly described and deserves further investigation in association with antibacterial agents, such as antibiotics and AMPs with antibacterial activity, or alternatively the application of broad-spectrum antimicrobial agents that target both aerobic and anaerobic bacteria, as well as fungi. Accordingly, the aim of this review is to unravel the molecular mechanisms by which AMPs achieve their dual antimicrobial and wound-healing properties, and to discuss how these are currently being applied as promising therapies against polymicrobial-infected chronic wounds such as DFUs.

Comparative study of culture, next-generation sequencing, and immunoassay for identification of pathogen in diabetic foot ulcer

Treatment of deep musculoskeletal infection (MSKI) begins with accurate identification of the offending pathogen, surgical excision/debridement, and a course of culture-directed antibiotics. Despite this, the incidence of recurrent infection continues to rise. A major contributor to this is inaccurate or negative initial cultures. Accurate identification of the main pathogen is paramount to treatment success. This is especially important in treating diabetic foot infections (DFIs) with limb salvage efforts. This study seeks to utilize standard culture, next-generation sequencing (NGS), and immunoassay for newly synthesized antibodies (NSA) to Staphylococcus aureus and Streptococcus agalactiae for diagnosis. This is a level II prospective observational study approved by our IRB. Thirty patients > 18 years of age who presented with a DFI and underwent surgical debridement or amputation by a single academic orthopedic surgeon from October 2018 to September 2019 were enrolled. Intraoperative samples were obtained from the base of the wound and sent for culture, NGS, and a peripheral blood sample was obtained at the time of diagnosis. NGS and culture were highly correlated for S. aureus (κ = 0.86) and S. agalactiae (κ = 1.0), NSA immunoassay and culture demonstrated a fair correlation for S. aureus (κ = 0.18) and S. agalactiae (κ = 0.67), and NGS and NSA immunoassay demonstrated fair correlation for S. aureus (κ = 0.1667) and S. agalactiae (κ = 0.67). Our study demonstrates a high concordance between culture and NGS in identifying the dominant pathogen in DFU. NGS may be a useful adjunct in DFI diagnosis.

Pressure ulcers microbiota dynamics and wound evolution

Bacterial species and their role in delaying the healing of pressure ulcers (PU) in spinal cord injury (SCI) patients have not been well described. This pilot study aimed to characterise the evolution of the cutaneous microbiota of PU in SCI cohort. Twenty-four patients with SCI from a French neurological rehabilitation centre were prospectively included. PU tissue biopsies were performed at baseline (D0) and 28 days (D28) and analysed using 16S rRNA gene-based sequencing analysis of the V3–V4 region. At D0, if the overall relative abundance of genus highlighted a large proportion of Staphylococcus, Anaerococcus and Finegoldia had a significantly higher relative abundance in wounds that stagnated or worsened in comparison with those improved at D28 (3.74% vs 0.05%; p = 0.015 and 11.02% versus 0.16%; p = 0.023, respectively). At D28, Proteus and Morganella genera were only present in stagnated or worsened wounds with respectively 0.02% (p = 0.003) and 0.01% (p = 0.02). Moreover, Proteus, Morganella, Anaerococcus and Peptoniphilus were associated within the same cluster, co-isolated from biopsies that had a poor evolution. This pathogroup could be a marker of wound degradation and Proteus could represent a promising target in PU management.

Priority effects dictate community structure and alter virulence of fungal-bacterial biofilms

Polymicrobial biofilms are a hallmark of chronic wound infection. The forces governing assembly and maturation of these microbial ecosystems are largely unexplored but the consequences on host response and clinical outcome can be significant. In the context of wound healing, formation of a biofilm and a stable microbial community structure is associated with impaired tissue repair resulting in a non-healing chronic wound. These types of wounds can persist for years simmering below the threshold of classically defined clinical infection (which includes heat, pain, redness, and swelling) and cycling through phases of recurrent infection. In the most severe outcome, amputation of lower extremities may occur if spreading infection ensues. Here we take an ecological perspective to study priority effects and competitive exclusion on overall biofilm community structure in a three-membered community comprised of strains of Staphylococcus aureus, Citrobacter freundii, and Candida albicans derived from a chronic wound. We show that both priority effects and inter-bacterial competition for binding to C. albicans biofilms significantly shape community structure on both abiotic and biotic substrates, such as ex vivo human skin wounds. We further show attachment of C. freundii to C. albicans is mediated by mannose-binding lectins. Co-cultures of C. freundii and C. albicans trigger the yeast-to-hyphae transition, resulting in a significant increase in neutrophil death and inflammation compared to either species alone. Collectively, the results presented here facilitate our understanding of fungal-bacterial interactions and their effects on host-microbe interactions, pathogenesis, and ultimately, wound healing.

Next-Generation Sequencing for Pathogen Identification in Infected Foot Ulcers

Background:

Accurate identification of primary pathogens in foot infections remains challenging due to the diverse microbiome. Conventional culture may show false-positive or false-negative growth, leading to ineffective postoperative antibiotic treatment. Next-generation sequencing (NGS) has been explored as an alternative to standard culture in orthopedic infections. NGS is highly sensitive and can detect an entire bacterial genome along with genes conferring antibiotic resistance in a given sample. We investigated the potential use of NGS for accurate identification and quantification of microbes in infected diabetic foot ulcer (DFU). We hypothesize that NGS will aid identification of dominant pathogen and provide a more complete profile of microorganisms in infected DFUs compared to the standard culture method.

Methods:

Data were prospectively collected from 30 infected DFU patients who underwent operative treatment by a fellowship-trained orthopedic foot and ankle surgeon from October 2018 to September 2019. The average age of the patient was 60.4 years. Operative procedures performed were irrigation and debridement (12), toe or ray amputation (13), calcanectomies (4), and below-the-knee amputation (1). Infected bone specimens were obtained intraoperatively and processed for standard culture and NGS. Concordance between the standard culture and NGS was assessed.

Results:

In 29 of 30 patients, pathogens were identified by both NGS and culture, with a concordance rate of 70%. In standard culture, Staphylococcus aureus (58.6%) was the most common pathogen, followed by coagulase-negative Staphylococcus (24.1%), Corynebacterium striatum (17.2%), and Enterococcus faecalis (17.2%). In NGS, Finegoldia magna (44.8%) was the most common microorganism followed by S. aureus (41.4%), and Anaerococcus vaginalis (24.1%). On average, NGS revealed 5.1 (range, 1-11) pathogens in a given sample, whereas culture revealed 2.6 (range, 1-6) pathogens.

Conclusion:

NGS is an emerging molecular diagnostic method of microbial identification in orthopedic infection. It frequently provides different profiles of microorganisms along with antibiotic-resistant gene information compared to conventional culture in polymicrobial foot infection. Clinical use of NGS for management of foot and ankle infections warrants further investigation.

Level of Evidence:

Level II, diagnostic study.

Factors related to the composition and diversity of wound microbiota investigated using culture-independent molecular methods: a scoping review

All open wounds are often colonized by commensal microbes as a loss of skin can provide a ready portal of entry for microorganisms. Although the wound microbiota is known to be associated with wound infection and with delayed healing, the factors related to the formations of wound microbiota contributing to such poor clinical outcomes are not clear and have not led to effective infection prevention interventions. This review aimed to scope the factors related to the composition and diversity of wound microbiota that have been investigated using culture-independent molecular methods. Original articles on wound microbiota published from January 1986 to February 2020 were included in this review. Thirty-one articles met the inclusion criteria and were grouped according to wound types: chronic, acute, and animal model wounds. The factors identified were categorized according to patient characteristics, wound characteristics, treatment, and sampling. Although some studies reported the effect size of the factors, the values were small. No studies elucidated the mechanism of wound microbiota formation. The results of this scoping review highlight that the factors associated with the diversity of wound microbiota are poorly understood and that further studies are needed.

The effect of platelet-rich plasma-fibrin glue dressing in combination with oral vitamin E and C for treatment of non-healing diabetic foot ulcers: a randomized, double-blind, parallel-group, clinical trial

OBJECTIVE

The current study assesses the effects of platelet-rich plasma-fibrin glue (PRP-FG) dressing along with oral vitamin E and C on wound healing and biochemical markers in patients with non-healing diabetic foot ulcers (non-healing DFU).

METHODS

This randomized controlled trial was performed on 25 patients with non-healing DFU. Patients were treated with PRP-FG dressing plus oral vitamin E and C (intervention group) or PRP-FG dressing plus placebo (control group) for 8 weeks.

RESULTS

Eight weeks after treatment, six wounds in the intervention group and two wounds in the control group were completely closed, and also wound size significantly reduced in both intervention and control groups (p < 0.05). This reduction in wound size was significantly greater in the intervention group compared to the control group (p = 0.019). Also, a significant decrease in prooxidant-antioxidant balance (PAB) , ESR, and hs-CRP was observed in the intervention group compared to the control group (p < 0.05).

CONCLUSION

Our results showed that PRP-FG dressing along with oral vitamin E and C could be used to increase wound healing in patients with non-healing DFU by enhancing the wound healing process and reducing oxidative stress.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT04315909).

Infectious Osteomyelitis: Marrying Bone Biology and Microbiology to Shed New Light on a Persistent Clinical Challenge

Infections of bone occur in a variety of clinical settings, ranging from spontaneous isolated infections arising from presumed hematogenous spread to those associated with skin and soft tissue wounds or medical implants. The majority are caused by the ubiquitous bacterium Staphyloccocus (S.) aureus, which can exist as a commensal organism on human skin as well as an invasive pathogen, but a multitude of other microbes are also capable of establishing bone infections. While studies of clinical isolates and small animal models have advanced our understanding of the role of various pathogen and host factors in infectious osteomyelitis (iOM), many questions remain unaddressed. Thus, there are many opportunities to elucidate host-pathogen interactions that may be leveraged toward treatment or prevention of this troublesome problem. Herein, we combine perspectives from bone biology and microbiology and suggest that interdisciplinary approaches will bring new insights to the field. © 2021 American Society for Bone and Mineral Research (ASBMR).

Intraoperative Site Vancomycin Powder Application in Infected Diabetic Heel Ulcers With Calcaneal Osteomyelitis

BACKGROUND

Intraoperative site application of vancomycin powder has been found to be beneficial in foot and ankle surgery among diabetic patients undergoing elective procedures. However, there are concerns for risks such as selection of multidrug-resistant bacteria, local tissue irritation, and increased wound complications. The clinical utility of intraoperative site vancomycin powder application in infected diabetic foot ulcer surgery is unknown. We aimed to report the clinical outcomes of partial or total calcanectomy for diabetic heel ulcer (DHU) and determine if intraoperative site application of vancomycin powder placement at the time of wound closure leads to improved clinical outcomes.

METHODS

A current procedural terminology query (CPT 28120: partial excision bone; talus or calcaneus) was run that identified 35 patients representing 38 calcanectomies performed secondary to infected DHU with calcaneal osteomyelitis. An initial group of 25 patients did not receive intraoperative site vancomycin powder, whereas the following 13 cases received intraoperative site vancomycin powder. Demographics, clinical characteristics, comorbidities, operative complications, unexpected return to the operating room (RTOR), and revision amputations were recorded for each patient. Average follow-up was 26.1 (6.5-51.6) months.

RESULTS

There was a significantly higher rate of RTOR among the vancomycin powder cohort (VANC) relative to the no-vancomycin cohort (No-VANC) (84.6% vs 36.0%, P = .038). Of the 13 VANC patients, 3 healed the wound and did not require RTOR, 2 underwent below-knee amputation (BKA), 2 received irrigation and debridement (I&D), and 6 underwent revision or total calcanectomies. Of the 25 No-VANC patients, 17 healed the wound, 4 underwent BKAs, 1 received an I&D, and 2 required revision or total calcanectomy. There was a trend toward increased rates of revision calcanectomy and BKA among the VANC cohort, but this was not statistically significant (61.5% vs 28.0%, P = .079).

CONCLUSION

Partial or total calcanectomies for the management of infected DHU resulted in an overall healing rate of 50.0%, unplanned RTOR and revision calcanectomy rate of 39.5%, and a limb salvage rate of 82.6%. We found no clinical benefit with the intraoperative site application of vancomycin powder.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

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.

Biofilms in Diabetic Foot Ulcers: Significance and Clinical Relevance

Foot infections are the main disabling complication in patients with diabetes mellitus. These infections can lead to lower-limb amputation, increasing mortality and decreasing the quality of life. Biofilm formation is an important pathophysiology step in diabetic foot ulcers (DFU)-it plays a main role in the disease progression and chronicity of the lesion, the development of antibiotic resistance, and makes wound healing difficult to treat. The main problem is the difficulty in distinguishing between infection and colonization in DFU. The bacteria present in DFU are organized into functionally equivalent pathogroups that allow for close interactions between the bacteria within the biofilm. Consequently, some bacterial species that alone would be considered non-pathogenic, or incapable of maintaining a chronic infection, could co-aggregate symbiotically in a pathogenic biofilm and act synergistically to cause a chronic infection. In this review, we discuss current knowledge on biofilm formation, its presence in DFU, how the diabetic environment affects biofilm formation and its regulation, and the clinical implications.

Staphylococcus aureus Osteomyelitis: Bone, Bugs, and Surgery

Osteomyelitis, or inflammation of bone, is most commonly caused by invasion of bacterial pathogens into the skeleton. Bacterial osteomyelitis is notoriously difficult to treat, in part because of the widespread antimicrobial resistance in the preeminent etiologic agent, the Gram-positive bacterium Staphylococcus aureus Bacterial osteomyelitis triggers pathological bone remodeling, which in turn leads to sequestration of infectious foci from innate immune effectors and systemically delivered antimicrobials. Treatment of osteomyelitis therefore typically consists of long courses of antibiotics in conjunction with surgical debridement of necrotic infected tissues. Even with these extreme measures, many patients go on to develop chronic infection or sustain disease comorbidities. A better mechanistic understanding of how bacteria invade, survive within, and trigger pathological remodeling of bone could therefore lead to new therapies aimed at prevention or treatment of osteomyelitis as well as amelioration of disease morbidity. In this minireview, we highlight recent developments in our understanding of how pathogens invade and survive within bone, how bacterial infection or resulting innate immune responses trigger changes in bone remodeling, and how model systems can be leveraged to identify new therapeutic targets. We review the current state of osteomyelitis epidemiology, diagnostics, and therapeutic guidelines to help direct future research in bacterial pathogenesis.

Evolving concepts in bone infection: redefining "biofilm", "acute vs. chronic osteomyelitis", "the immune proteome" and "local antibiotic therapy"

Osteomyelitis is a devastating disease caused by microbial infection of bone. While the frequency of infection following elective orthopedic surgery is low, rates of reinfection are disturbingly high. Staphylococcus aureus is responsible for the majority of chronic osteomyelitis cases and is often considered to be incurable due to bacterial persistence deep within bone. Unfortunately, there is no consensus on clinical classifications of osteomyelitis and the ensuing treatment algorithm. Given the high patient morbidity, mortality, and economic burden caused by osteomyelitis, it is important to elucidate mechanisms of bone infection to inform novel strategies for prevention and curative treatment. Recent discoveries in this field have identified three distinct reservoirs of bacterial biofilm including: Staphylococcal abscess communities in the local soft tissue and bone marrow, glycocalyx formation on implant hardware and necrotic tissue, and colonization of the osteocyte-lacuno canalicular network (OLCN) of cortical bone. In contrast, S. aureus intracellular persistence in bone cells has not been substantiated in vivo, which challenges this mode of chronic osteomyelitis. There have also been major advances in our understanding of the immune proteome against S. aureus, from clinical studies of serum antibodies and media enriched for newly synthesized antibodies (MENSA), which may provide new opportunities for osteomyelitis diagnosis, prognosis, and vaccine development. Finally, novel therapies such as antimicrobial implant coatings and antibiotic impregnated 3D-printed scaffolds represent promising strategies for preventing and managing this devastating disease. Here, we review these recent advances and highlight translational opportunities towards a cure.