The role of anaerobes in diabetic foot infections

Antibiotic Stewardship in the Management of Infected Diabetic Foot Ulcer Disease in Less Developed Countries

BACKGROUND

Diabetic foot ulcers in developing countries often become infected. The healthcare systems are often not equipped to conduct the culture and the sensitivity tests required for prescribing a targeted antibiotic treatment for diabetic foot infection (DFI).

METHODS

We evaluate antibiotic stewardship programmes for DFIs, at every level of health care, with an emphasis on resource-poor settings such as in Africa.

RESULTS

The management of DFI very often is adapted to the financial and practical realities of the resource-poor regions. The application of the point-of-care Gram stain of deep tissue samples is efficient, rapid, low cost and ubiquitously available. Upon the identification of the predominant pathogen in the Gram stain, a semi-quantitative preemptive antibiotic treatment can be started in accordance with the World Health Organization Aware, Watch and Restrict Essential Medicine List. This list is catered to every country and is a powerful tool. However, some basic knowledge of the local microbiological epidemiology is necessary to choose the most appropriate agent. We report our experience on using the rapidly available Gram stain for narrowing the preemptive choice of listed antibiotic agents, as an economic tool for antibiotic stewardship in DFIs.

CONCLUSIONS

In the practical and resource-saving management of DFI, the 'therapeutic' use of Gram stains is not common in resource-rich countries but should be added to the arsenal of the general efforts for antibiotic stewardship.

Anaerobes in diabetic foot infections: pathophysiology, epidemiology, virulence, and management

SUMMARYDiabetic foot infections (DFI) are a public health problem worldwide. DFI are polymicrobial, biofilm-associated infections involving complex bacterial communities organized in functional equivalent pathogroups, all including anaerobes. Indeed, multiple pathophysiological factors favor the growth of anaerobes in this context. However, the prevalence, role, and contribution of anaerobes in wound evolution remain poorly characterized due to their challenging detection. Studies based on culture reviewed herein showed a weighted average of 17% of patients with anaerobes. Comparatively, the weighted average of patients with anaerobes identified by 16S rRNA gene sequencing was 83.8%. Culture largely underestimated not only the presence but also the diversity of anaerobes compared with cultivation-independent approaches but both methods showed that anaerobic Gram-negative bacilli and Gram-positive cocci were the most commonly identified in DFI. Anaerobes were more present in deeper lesions, and their detection was associated with fever, malodorous lesions, and ulcer depth and duration. More specifically, initial abundance of Peptoniphilus spp. was associated with ulcer-impaired healing, Fusobacterium spp. detection was significantly correlated with the duration of DFI, and the presence of Bacteroides spp. was significantly associated with amputation. Antimicrobial resistance of anaerobes in DFI remains slightly studied and warrants more consideration in the context of increasing resistance of the most frequently identified anaerobes in DFI. The high rate of patients with DFI-involving anaerobes, the increased knowledge on the species identified, their virulence factors, and their potential role in wound evolution support recommendations combining debridement and antibiotic therapy effective on anaerobes in moderate and severe DFI.

PET/CT and SPECT/CT for Infection in Joints and Bones: An Overview and Future Directions

Infections of the bones and joints, if misdiagnosed, may result in serious morbidity and even mortality. A prompt diagnosis followed by appropriate management may reduce the socioeconomic impact of bone and joint infections. Morphologic imaging such as ultrasound and plain radiographs form the first line investigations, however, in early infections findings may be negative or nonspecific. Nuclear medicine imaging techniques play a complementary role to morphologic imaging in the diagnosis of bone and joint infections. The availability of hybrid systems (SPECT/CT, SPECT/MRI, PET/CT or PET/MRI) offers improved specificity with ability to assess the extent of infection. Bone scans are useful as a gatekeeper wherein negative scans rule out sepsis with a good accuracy, however positive scans are nondiagnostic and more specific tracers should be considered. These include the use of labeled white blood cells and antigranulocyte antibodies. Various qualitative and quantitative interpretation criteria have been suggested to improve the specificity of the scans. PET has better image resolution and 18F-FDG is the major tracer for PET imaging with applications in oncology and inflammatory/infective disorders. It has demonstrated improved sensitivity over the SPECT based tracers, however, still suffers from lack of specificity. 18F-FDG PET has been used to monitor therapy in bone and joint infections. Other less studied, noncommercialized SPECT and PET tracers such as 111In-Biotin, 99mTc-Ubiquicidin, 18F-Na-Fluoride, 18F-labeled white blood cells and 124I-Fialuridine to name a few have shown great promise, however, their role in various bone and joint infections has not been established. Hybrid imaging with PET or PET/MRI offers huge potential for improving diagnostics in infections of the joints and bones.

Diabetic Foot Infections in the Emergency Department

Diabetic foot infection (DFI) is among the most common diabetic complications requiring hospitalization. Prompt emergency department diagnosis and evidence-based management can prevent eventual amputation and associated disability and mortality. Underlying neuropathy, arterial occlusion, immune dysfunction, and hyperglycemia-associated dehydration and ketoacidosis can all contribute to severity and conspire to make DFI diagnosis and management difficult. Serious complications include osteomyelitis, necrotizing infection, and sepsis. Practice guidelines are designed to assist frontline providers with correct diagnosis, categorization, and treatment decisions. Management generally includes a careful lower extremity examination and plain x-ray, obtaining appropriate tissue cultures, and evidence-based antibiotic selection tailored to severity.

Toward non-invasive collection methods for sampling the microbiome of diabetic foot ulcers

Identifying the microbiome within chronic diabetic foot ulcers is essential if effective antimicrobial therapies are to be administered. Using culture and 16S rRNA gene sequencing, the aim of this study was to compare the microbiome of paired tissue scraping samples with swab samples, collected from participants during attendance at a high-risk foot clinic. The mean richness of cultured swab and tissue scraping samples was consistent, with anaerobes infrequently isolated from both sample types. Comparing percentage frequencies of detection of selected genera of known and potential pathogens namely Staphylococcus, Streptococcus, Enterococcus, Corynebacterium, Enterobacteriaceae and Pseudomonas from cultured and sequenced swab and tissue scrapings indicated that both collection methods captured varying percentages of all the selected genera. The mean abundance of sequenced samples was not significantly different between swabs and tissue scrapings. The mean richness or number of distinct operational taxonomic units (OTUs) and Shannon's H diversity index were not significantly different between the two collection methods. The mean relative abundance of the selected genera of known and potential pathogens, including anaerobes Anaerococcus and Finegoldia, was higher in swabs compared with tissue scrapings and significantly so in Staphylococcus and Pseudomonas genera. Multivariate analyses confirmed no significant differences between the bacterial community compositions of the paired samples. These results suggest that tissue scrapings and swabs can effectively capture the microbiome of chronic DFUs using culture and 16S rRNA gene sequencing.

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.

Biofilm and wound healing: from bench to bedside

The bubbling community of microorganisms, consisting of diverse colonies encased in a self-produced protective matrix and playing an essential role in the persistence of infection and antimicrobial resistance, is often referred to as a biofilm. Although apparently indolent, the biofilm involves not only inanimate surfaces but also living tissue, making it truly ubiquitous. The mechanism of biofilm formation, its growth, and the development of resistance are ever-intriguing subjects and are yet to be completely deciphered. Although an abundance of studies in recent years has focused on the various ways to create potential anti-biofilm and antimicrobial therapeutics, a dearth of a clear standard of clinical practice remains, and therefore, there is essentially a need for translating laboratory research to novel bedside anti-biofilm strategies that can provide a better clinical outcome. Of significance, biofilm is responsible for faulty wound healing and wound chronicity. The experimental studies report the prevalence of biofilm in chronic wounds anywhere between 20 and 100%, which makes it a topic of significant concern in wound healing. The ongoing scientific endeavor to comprehensively understand the mechanism of biofilm interaction with wounds and generate standardized anti-biofilm measures which are reproducible in the clinical setting is the challenge of the hour. In this context of "more needs to be done", we aim to explore various effective and clinically meaningful methods currently available for biofilm management and how these tools can be translated into safe clinical practice.

Influence of Skin Commensals on Therapeutic Outcomes of Surgically Debrided Diabetic Foot Infections-A Large Retrospective Comparative Study

In diabetic foot infections (DFI), the clinical virulence of skin commensals are generally presumed to be low. In this single-center study, we divided the wound isolates into two groups: skin commensals (coagulase-negative staphylococci, micrococci, corynebacteria, cutibacteria) and pathogenic pathogens, and followed the patients for ≥ 6 months. In this retrospective study among 1018 DFI episodes (392 [39%] with osteomyelitis), we identified skin commensals as the sole culture isolates (without accompanying pathogenic pathogens) in 54 cases (5%). After treatment (antibiotic therapy [median of 20 days], hyperbaric oxygen in 98 cases [10%]), 251 episodes (25%) were clinical failures. Group comparisons between those growing only skin commensals and controls found no difference in clinical failure (17% vs. 24 %, p = 0.23) or microbiological recurrence (11% vs. 17 %, p = 0.23). The skin commensals were mostly treated with non-beta-lactam oral antibiotics. In multivariate logistic regression analysis, the isolation of only skin commensals was not associated with failure (odds ratio 0.4, 95% confidence interval 0.1-3.8). Clinicians might wish to consider these isolates as potential pathogens when selecting a targeted antibiotic regimen, which may also be based on oral non-beta-lactam antibiotic agents effective against the corresponding skin pathogens.

Microbiology of diabetic foot osteomyelitis - Is it geographically variable?

INTRODUCTION

Diabetic foot osteomyelitis (DFO) is a dreaded complication as both diagnosis and treatment of the condition is laborious. However, for proper decision on antibiotics in medical management of DFO, accurate determination of microbes is necessary to narrow the spectrum of coverage and to reduce adverse effects of long-term administration of antibiotics. With differing pattern of use of antimicrobials and their resistance pattern in different countries, it is empirical to determine the microbiological characteristics of bone cultures in DFO from a referral institute in South India.

MATERIALS AND METHODS

This study was a retrospective chart review of all cases of proven DFO who had consented for debridement and bone culture or those who underwent amputation. Both deep soft tissue (DST) and bone cultures were obtained for aerobic bacteria. Clinical characteristics and site(s) of DFO were recorded. Investigations for peripheral artery disease were performed if clinically indicated.

RESULTS

In all, 105 patients with DFO were reviewed. Mean age was 62 years and 70% were men. Of those who were screened, 57% had evidence of peripheral arterial disease by arterial doppler. 46% of bone culture samples were sterile. Gram- negative organisms were more common (58%). Following staphylococcus, pseudomonas was the second common isolate. Of total staphylococcal isolates 37% were MRSA and 33% of klebsiella isolates were ESBL producing. Concordance rate between DST and bone cultures was 66%. 90% were mono-bacterial isolates. The commonest site of involvement of DFO was terminal phalanges of toes rather than base of 1st metatarsal.

CONCLUSION

Widespread use of antibiotics, tropical climate and route of entry of organisms causing DFO differed in our cohort of patients. Further studies from different regions of world would shed light onto different pattern of microbes causing DFO.

Prevalence of Extended-Spectrum β-Lactamase and Carbapenemase Producers of Gram-Negative Bacteria, and Methicillin-Resistant Staphylococcus aureus in Isolates from Diabetic Foot Ulcer Patients in Ethiopia

Background

Infectious diabetic foot ulcers (IDFU) are a widespread health issue that affects people all over the world. IDFU, like other medical disorders, can have negative implications if drug resistance develops. Clinicians will be able to choose the optimal antibiotics to treat impacted patients based on the antibiotic susceptibility pattern of bacterial strains. In this project, we attempted to evaluate the levels of extended-spectrum beta-lactamase (ESBL), carbapenemase, and MRSA in patients with diabetic foot ulcers.

Methods

A sterile swab was used to collect a sample from the leg ulcer, while a sterile needle was used to collect the aspirated pus. Bacteria identification and antibiotic susceptibility tests are carried out based on conventional bacterial culture. The double-disc inactivation method and modified carbapenem (meropenem) were used to screen the production of ESBL and carbapenemase.

Results

Of the 76 isolates tested, 53.9% (41/76) were phenotypically ESBL producers. K. pneumoniae 75% (6/8), Acinetobacter species 75% (9/12), Serratia species 75% (3/4), Pseudomonas species 64.3% (14/9), E. coli 57.8% (11/19), Citrobacter species 50% (2/4) and Proteus mirabilis 25% (1/4) had the highest frequency of ESBL production. Of the 68 GNB isolates tested, 27.9% (19/68) were carbapenemase-producing organisms. K. pneumoniae 62.5% (5/8), Serratia 50% (3/6), Acinetobacter species 40% (4/10), Pseudomonas species 23.5% (4/17) and E. coli 15.8% (3/19) are the top five major carbapenemase producers. In this study, 32 isolates of Staphylococcus aureus were tested for methicillin resistance. Among them, 81.3% (26/32) were methicillin-resistant Staphylococcus aureus (MRSA), and 18.7% (6/32) of the remaining isolates were methicillin-sensitive Staphylococcus aureus (MSSA).

Conclusion

The result draws attention to the management of diabetic foot ulcer infections based on the results of microbiological analysis and drug susceptibility testing.

Moderate to Severe Soft Tissue Diabetic Foot Infections: A Randomized, Controlled, Pilot Trial of Post-debridement Antibiotic Treatment for 10 versus 20 days

BACKGROUND

The optimal duration of antibiotic therapy for soft-tissue infections of the diabetic foot remains unknown.

OBJECTIVE

We determine if antibiotic therapy after debridement for a short (10 days), compared with a long (20 days), duration for soft-tissue infections of the diabetic foot results in similar rates of clinical remission and adverse events (AE).

SUMMARY OF BACKGROUND DATA

The optimal duration of systemic antibiotic therapy, after successful debridement, for soft tissue infections of diabetic patients is unknown. Because of the high recurrence risk, overuse is commonplace.

METHODS

This was a randomized, controlled, non-inferiority pilot trial of cases of diabetic foot infection (excluding osteomyelitis) with the primary outcome of "clinical remission at 2-months follow-up".

RESULTS

Among 66 enrolled episodes (17% females; median age 71 years), we randomized 35 to the 10-day arm and 31 to the 20-day arm. The median duration of the parenteral antibiotic therapy was 1 day, with the remainder given orally. In the intention-to-treat population, we achieved clinical remission in 27 (77%) patients in the 10-day arm compared to 22 (71%) in the 20-days arm ( P = 0.57). There were a similar proportion in each arm of AE (14/35 versus 11/31; P = 0.71), and remission in the per-protocol population (25/32 vs 18/27; P = 0.32). Overall, 8 soft tissue DFIs in the 10-day arm and 5 cases in the 20-day arm recurred as a new osteomyelitis [8/35 (23%) versus 5/31 (16%); P = 0.53]. Overall, the number of recurrences limited to the soft tissues was 4 (6%). By multivariate analysis, rates of remission (intention-to-treat population, hazard ratio 0.6, 95%CI 0.3-1.1; per-protocol population 0.8, 95%CI 0.4-1.5) and AE were not significantly different with a 10-day compared to 20-day course.

CONCLUSIONS

In this randomized, controlled pilot trial, post-debridement antibiotic therapy for soft tissue DFI for 10 days gave similar (and non-inferior) rates of remission and AEs to 20 days. A larger confirmatory trial is under way.

TRIAL REGISTRATION

ClinicalTrials NCT03615807.

Pseudomonal Diabetic Foot Infections: Vive la Différence?

Objective

To assess the outcomes of diabetic foot infections (DFIs) due to Pseudomonas aeruginosa.

Patients and Methods

From April 24, 2013 to July 31, 2016, we analyzed data from patients prospectively enrolled in our clinical pathway of DFIs, comparing those with infection due to Pseudomonas with those without infection due to Pseudomonas.

Results

Overall, we assessed 1018 cases of DFIs: 392 with osteomyelitis and 626 with only soft tissue infections. The prevalence of P aeruginosa in deep wound cultures was 10% (104/1018); of the 1018 cultures, 22 were monomicrobial, 82 were polymicrobial, and 46 were with osteomyelitis. Overall, the patients were treated with a median of 1 surgical debridement and a total of 20 days of antibiotic therapy. In a comparison of crude groups, the proportion of clinical failures was significantly higher with Pseudomonas than with other pathogens (36/104 [35%] vs 218/914 [24%], respectively; P=.02). A multivariate analysis showed that pseudomonal DFIs did not recur more often than nonpseudomonal DFIs (hazard ratio, 1.0; 95% confidence interval, 0.6-1.7). Among the 104 cases of pseudomonal DFIs, there was no association between failure of treatment and the total duration of antibiotic therapy, duration of intravenous therapy, duration of combined antibiotic therapy with more than 1 agent, or duration of oral (fluoroquinolone) therapy. Among 15 cases of pseudomonal recurrence, 2 (13%) developed resistance to the antibiotic agent used for the index episode.

Conclusion

For DFIs caused by P aeruginosa, other than choosing an antibiotic agent that is active against the organism, it does not appear necessary to treat with a different therapeutic regimen compared with the treatment of nonpseudomonal DFIs. There is no difference!

Diabetic foot infections: A microbiologic review

Diabetes mellitus continues to be an increasingly common comorbidity. Diabetic foot infections are one of the most common causes of hospitalization in this population, and account for a significant portion of increased hospitalization and healthcare expenditure. Complications, such as osteomyelitis, can necessitate the use of multiple, prolonged antibiotic courses. These courses often consist of broad-spectrum, empiric therapy determined by organisms considered to be commonly associated with these types of infections. Extended periods of broad-spectrum antibiotic regimens can contribute to antibiotic resistance and ultimately limit future treatment options. Furthermore, patient specific risk factors can impact the microbiologic diversity found in these infections. As a result, it is difficult to determine if a single empiric regimen is appropriate for all instances of diabetic foot infections.

OBJECTIVES AND METHODS

This review analyzes global literature relating to the culture methods, incidence, risk factors, resistance patterns, and geographic distribution of the microorganisms isolated from diabetic foot infections using the PRISMA statement for systematic review and meta-analysis reporting.

RESULTS

Staphylococcus aureus remains a significant pathogen, with a growing incidence of Pseudomonas aeruginosa and MDR gram-negative bacilli.

CONCLUSIONS

Though some individualized risk factors can be useful, local epidemiology and resistance patterns remain essential for antibiotic treatment considerations.

Short and oral antimicrobial therapy for diabetic foot infection: a narrative review of current knowledge

Diabetic foot infection is a frequent complication in long-standing diabetes mellitus. For antimicrobial therapy of this infection, both the optimal duration and the route of administration are often based more on expert opinion than on published evidence. We reviewed the scientific literature, specifically seeking prospective trials, and aimed at addressing two clinical issues: (1) shortening the currently recommended antibiotic duration and (2) using oral (rather than parenteral) therapy, especially after the patient has undergone debridement and revascularization. We also reviewed some older key articles that are critical to our understanding of the treatment of these infections, particularly with respect to diabetic foot osteomyelitis. Our conclusion is that the maximum duration of antibiotic therapy for osteomyelitis should be no more than to 4-6 weeks and might even be shorter in selected cases. In the future, in addition to conducting randomized trials and propagating national and international guidance, we should also explore innovative strategies, such as intraosseous antibiotic agents and bacteriophages.

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.

Retrospective Observational Study on Microbial Contamination of Ulcerative Foot Lesions in Diabetic Patients

According to recent studies, there are almost 435 million people worldwide with diabetes mellitus. It is estimated that of these 148 million will develop Diabetic foot ulcers (DFUs) during their lifetime, of which 35 to 50% will be infected. In this scenario, the presence and frequency of pathogenic microorganisms and their level of susceptibility to the most frequent classes of antibiotics used to treat this pathological condition from patients with DFUs admitted to the outpatient clinic of vascular surgery of the Federico II University Hospital of Naples from January 2019 to March 2021 were investigated. Furthermore, the diabetic population characteristics under study (i.e., general, clinical, and comorbidities) and the pathogenic bacteria isolated from lesions were also considered. Bacterial strains poorly susceptible to antibiotics were more frequent in polymicrobial infections than in monomicrobial infections. β-Lactams showed the highest levels of resistance, followed by fluoroquinolones, aminoglycosides, and finally macrolides. The main findings of the study demonstrated that the occurrence of resistant microorganisms is the dominant factor in ulcer healing; thus it is essential to investigate the antibiotics’ susceptibility before setting antibiotic therapy to avoid inappropriate prescriptions that would affect the treatment and increase the development and spread of antibiotic resistance.

Microbial Species Isolated from Infected Wounds and Antimicrobial Resistance Analysis: Data Emerging from a Three-Years Retrospective Study

The antimicrobial resistance is a topic of global interest in the treatment of wound infections. The goal of this retrospective study was both the identification of the microorganisms responsible for wound infections and the determination of their drug susceptibility pattern. The study was performed from 2017 to 2019 and included 239 patients. Thirty-four species were isolated by culture methods and identified and analysed for their susceptibility patterns to antimicrobials through the Walk Away automated system. The presence of one species was the most frequent condition (75.3%), whereas a co-infection was detected in 24.7% of samples. The most common species were Gram-negative (57.9%), amongst which the most prevalent were Pseudomonas aeruginosa (40.2%), Escherichia coli (20.7%), Proteus mirabilis (11.2%), and Acinetobacter baumannii/haemolyticus (9.5%). Gram-positive bacteria were observed in 36.6%, Staphylococcus aureus (79.4%) being the most predominant species. At least one resistance to antibiotics was detected in 88.2% of isolates, while a multi-drug-resistance versus no less than 6 antimicrobials was detected in 29.2% of isolates. Although multi-drug resistant species and co-infections were observed, those were less frequently observed at the wound site. These conditions make the microorganisms eradication more difficult. The detection of a polymicrobial infection and multi-drug resistant microorganisms followed by a proper therapeutic treatment would lead to the resolution of the infection, promoting wound healing and the limitation of the spread of antibiotic resistance.

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.

The microbiology of diabetic foot infections: a meta-analysis

Background

Diabetic foot ulcers are a common complication of poorly controlled diabetes and often become infected, termed diabetic foot infection. There have been numerous studies of the microbiology of diabetic foot infection but no meta-analysis has provided a global overview of these data. This meta-analysis aimed to investigate the prevalence of bacteria isolated from diabetic foot infections using studies of any design which reported diabetic foot infection culture results.

Methods

The Medline, EMBASE, Web of Science and BIOSIS electronic databases were searched for studies published up to 2019 which contained microbiological culture results from at least 10 diabetic foot infection patients. Two authors independently assessed study eligibility and extracted the data. The main outcome was the prevalence of each bacterial genera or species.

Results

A total of 112 studies were included, representing 16,159 patients from which 22,198 microbial isolates were obtained. The organism most commonly identified was Staphylococcus aureus, of which 18.0% (95% CI 13.8–22.6%; I² = 93.8% [93.0–94.5%]) was MRSA. Other highly prevalent organisms were Pseudomonas spp., E. coli and Enterococcus spp. A correlation was identified between Gross National Income and the prevalence of Gram positive or negative organisms in diabetic foot infections.

Conclusion

The microbiology of diabetic foot infections is diverse, but S. aureus predominates. The correlation between the prevalence of Gram positive and negative organisms and Gross National Income could reflect differences in healthcare provision and sanitation. This meta-analysis has synthesised multiple datasets to provide a global overview of the microbiology of diabetic foot infections that will help direct the development of novel therapeutics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06516-7.

Biofilms in Diabetic Foot Ulcers: Impact, Risk Factors and Control Strategies

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

Treating Diabetic Foot Osteomyelitis: A Practical State-of-the-Art Update

Background and Objectives: Diabetic foot osteomyelitis (DFO) can be difficult to treat and securing optimal clinical outcomes requires a multidisciplinary approach involving a wide variety of medical, surgical and other health care professionals, as well as the patient. Results of studies conducted in the past few years have allowed experts to formulate guidelines that can improve clinical outcomes. Material and Methods: We conducted a narrative review of the literature on treat- ment of DFO, with an emphasis on studies published in the last two years, especially regarding antimicrobial therapies and surgical approached to treatment of DFO, supplemented by our own extensive clinical and research experience in this field. Results: Major amputations were once com- mon for DFO but, with improved diagnostic and surgical techniques, "conservative" surgery (foot- sparing, resecting only the infected and necrotic bone) is becoming commonplace, especially for forefoot infections. Traditional antibiotic therapy, which has been administered predominantly in- travenously and frequently for several months, can often be replaced by appropriately selected oral antibiotic regimens following only a brief (or even no) parenteral therapy, and given for no more than 6 weeks. Based on ongoing studies, the recommended duration of treatment may soon be even shorter, especially for cases in which a substantial portion of the infected bone has been resected. Using the results of cultures (preferably of bone specimens) and antimicrobial stewardship princi- ples allows clinicians to select evidence-based antibiotic regimens, often of a limited pathogen spec- trum. Intra-osseous antimicrobial and surgical approaches to treatment are also evolving in light of ongoing research. Conclusions: In this narrative, evidenced-based review, taking consideration of principles of antimicrobial stewardship and good surgical practice, we have highlighted the recent literature and offered practical, state-of-the-art advice on the antibiotic and surgical management of DFO.

How good are clinicians in predicting the presence of Pseudomonas spp. in diabetic foot infections? A prospective clinical evaluation

Introduction

The most frequently prescribed empirical antibiotic agents for mild and moderate diabetic foot infections (DFIs) are amino-penicillins and second-generation cephalosporins that do not cover Pseudomonas spp. Many clinicians believe they can predict the involvement of Pseudomonas in a DFI by visual and/or olfactory clues, but no data support this assertion.

Methods

In this prospective observational study, we separately asked 13 experienced (median 11 years) healthcare workers whether they thought the Pseudomonas spp. would be implicated in the DFI. Their predictions were compared with the results of cultures of deep/intraoperative specimens and/or the clinical remission of DFI achieved with antibiotic agents that did not cover Pseudomonas.

Results

Among 221 DFI episodes in 88 individual patients, intraoperative tissue cultures grew Pseudomonas in 22 cases (10%, including six bone samples). The presence of Pseudomonas was correctly predicted with a sensitivity of 0.32, specificity of 0.84, positive predictive value of 0.18 and negative predictive value 0.92. Despite two feedbacks of the interim results and a 2-year period, the clinicians' predictive performance did not improve.

Conclusion

The combined visual and olfactory performance of experienced clinicians in predicting the presence of Pseudomonas in a DFI was moderate, with better specificity than sensitivity, and did not improve over time. Further investigations are needed to determine whether clinicians should use a negative prediction of the presence of Pseudomonas in a DFI, especially in settings with a high prevalence of pseudomonal DFIs.

Distribution and Antibiotic Resistance Patterns of Pathogenic Bacteria in Patients With Chronic Cutaneous Wounds in China

Background: To determine the distribution and antimicrobial susceptibility pattern of pathogenic bacteria in patients with chronic cutaneous wounds on a national scale. Methods: A retrospective study was conducted using the data recorded between January 1, 2018 and January1, 2020 in 195 hospitals across China. After screening the data, 815 patients with chronic wounds were finally analyzed. The data collected included information about the patients' general condition and local cutaneous wound assessments, especially microbial culture and antibiotic susceptibility tests. The analyses were performed using SPSS Version 26. Results: The study included 815 patients (290 [35.6%] females; 63 [50-74] years). The most common causes of chronic cutaneous wounds were diabetes (183, 22.5%), infection (178, 21.8%), and pressure (140, 17.2%). Among these, 521(63.9%) samples tested yielded microbial growth, including 70 (13.4%) polymicrobial infection and 451 (86.6%) monomicrobial infection. The positive rate of microbial culture was highest in wound tissue of ulcers caused by infection (87.6%), followed by pressure (77.1%), diabetes (68.3%), and venous diseases (67.7%). Bates-Jensen wound assessment tool (BWAT) scores >25 and wounds that lasted for more than 3 months had a higher positive rate of microbial culture. BWAT scores >25 and wounds in the rump, perineum, and feet were more likely to exhibit polymicrobial infection. A total of 600 strains were isolated, of which 46.2% (277 strains) were Gram-positive bacteria, 51.3% (308 strains) were Gram-negative bacteria, and 2.5% (15 strains) were fungi. The most common bacterial isolates were Staphylococcus aureus (29.2%), Escherichia coli (11.5%), Pseudomonas aeruginosa (11.0%), Proteus mirabilis (8.0%), and Klebsiella pneumoniae (5.8%). The susceptibility tests showed that 116 cultured bacteria were Multidrug resistant (MDR) strains. The resistance rates of S. aureus were 92.0% (161/175) to penicillin, 58.3% (102/175) to erythromycin, and 50.9% (89/175) to clindamycin. Vancomycin was the most effective antibiotic (0% resistance rate) against all Gram-positive bacteria. Besides, the resistance rates of E. coli were 68.1% (47/69) to ampicillin, 68.1% (47/69) to ciprofloxacin, 60.9% (42/69) to levofloxacin. However, all the isolated Gram-negative bacteria showed low resistance rates to tigecycline (3.9%) and amikacin (3.6%). Conclusions: The distribution of bacteria isolated from chronic cutaneous wounds varies with the BWAT scores, causes, duration, and the location of wounds. Multidrug resistance is a serious health issue, and therefore antibiotics used in chronic wounds must be under strict regulation. Our findings may help clinicians in making informed decisions regarding antibiotic therapy.

Osteoarticular infections: a specific program for older patients?

BACKGROUND

With the increasing number of elderly patients, arthroplasties, fractures and diabetic foot infections, the worldwide number of osteoarticular infections (OAI) among the elderly is concomitantly expected to rise.

AIMS

We explore existing scientific knowledge about OAI in the frail elderly population.

METHODS

We performed a literature search linking OAIs to geriatric patients and comparing elderly patients (> 65 years) with average adults (range 18-65 years).

RESULTS

In this literature, financial aspects, comparison of diverse therapies on quality of life, reimbursement policies, or specific guidelines or nursing recommendations are missing. Age itself was not an independent factor related to particular pathogens, prevention of OAI, nursing care, and outcomes of OAI. However, geriatric patients were significantly more exposed to adverse events of therapy. They had more co-morbidities and more conservative surgery for OAI.

CONCLUSION

Available literature regarding OAI management among elderly patients is sparse. In recent evaluations, age itself does not seem an independent factor related to particular epidemiology, pathogens, prevention, nursing care, rehabilitation and therapeutic outcomes of OAI. Future clinical research will concern more conservative surgical indications, but certainly reduce inappropriate antibiotic use.

An Integrated HOCl-Producing E-Scaffold Is Active against Monomicrobial and Polymicrobial Biofilms

Oxidizing agents like hypochlorous acid (HOCl) have antimicrobial activity. We developed an integrated electrochemical scaffold, or e-scaffold, that delivers a continuous low dose of HOCl aimed at targeting microbial biofilms without exceeding concentrations toxic to humans as a prototype of a device being developed to treat wound infections in humans. In this work, we tested the device against 33 isolates of bacteria (including isolates with acquired antibiotic resistance) grown as in vitro biofilms alongside 12 combinations of dual-species in vitro biofilms. Biofilms were grown on the bottoms of 12-well plates for 24 h. An integrated e-scaffold was placed atop each biofilm and polarized at 1.5 V for 1, 2, or 4 h. HOCl was produced electrochemically by oxidizing chloride ions (Cl^-) in solution to chlorine (Cl₂); dissolved Cl₂ spontaneously dissociates in water to produce HOCl. The cumulative concentration of HOCl produced at the working electrode in each well was estimated to be 7.89, 13.46, and 29.50 mM after 1, 2, and 4 h of polarization, respectively. Four hours of polarization caused an average reduction of 6.13 log₁₀ CFU/cm² (±1.99 log₁₀ CFU/cm²) of viable cell counts of monospecies biofilms and 5.53 log₁₀ CFU/cm² (±2.31 log₁₀ CFU/cm²) for the 12 dual-species biofilms studied. The described integrated e-scaffold reduces viable bacterial cell counts in biofilms formed by an array of antibiotic-susceptible and -resistant bacteria alone and in combination.

Microbiological profile and antimicrobial resistance among diabetic foot infections in Lebanon

Diabetic Foot Infection (DFI) is a challenging complication of diabetes mellitus with a high burden in the Middle East where there is a marked increase in diabetes prevalence and complications. Early detection of DFI and the infectious organisms could result in the early initiation of appropriate antibiotic therapy and improved outcomes. DFI microbiological profiles differ between countries. In our region, Western guidelines are used when initiating treatment for DFI in the absence of local guidance. The purpose of our study was to determine the microbiologic profile and antimicrobial susceptibility of the DFI admissions at a large tertiary referral centre in Beirut and review other reported series in Lebanon and our region. This is a retrospective observational study of patients with DFI admitted to the American University of Beirut Medical Centre from January 2008 to June 2017. The bacteriologic isolation and antimicrobial susceptibility tests were performed according to standard microbiological methods. Between 2008 and 2017, 319 diabetic patients with DFU were admitted to AUBMC, and deep-tissue cultures were taken for 179 patients. From 179 deep tissue cultures, 314 bacterial isolates were obtained. Fifty-four percent of patients had the polymicrobial infection. Aerobic gram-negative rods (GNR) were more prevalent than gram-positive cocci (GPC) (55%, 39%, respectively). The most common isolate was Escherichia coli (15%) followed by Enterococcus (14%) and Pseudomonas aeruginosa (11%). Staphylococcus aureus isolates accounted for 9% with 50% of them being methicillin-resistant (MRSA). Among Enterobacteriaceae, 37% of isolates were fluoroquinolone-resistant, 25% were ESBL producers, and 2% were carbapenem-resistant. Antibiotic resistance was significantly associated with prior usage of antibiotics. Anaerobes were isolated in 1% and Candida species in 5% of isolates. The sensitivity, specificity, PPV, and NPV of swab culture recovery of pathogens compared with deep tissue culture were (76%, 72%, 76%, 72%) and (94%, 81%, 91%, 86%) for gram-positive and gram-negative organisms, respectively. The microbiological profile of DFI in Lebanon is comparable to other countries in the MENA region with big differences compared with the West. Therefore, it is imperative to develop local guidelines for antimicrobial treatment. The high prevalence of GNR in DFI and the high fluoroquinolone resistance should be taken into consideration when choosing empiric antibiotics. Empiric treatment for MRSA or Pseudomonas does not appear necessary except for patients with specific risk factors.

The microbiome of diabetic foot ulcers: a comparison of swab and tissue biopsy wound sampling techniques using 16S rRNA gene sequencing

Background

Health-care professionals need to collect wound samples to identify potential pathogens that contribute to wound infection. Obtaining appropriate samples from diabetic foot ulcers (DFUs) where there is a suspicion of infection is of high importance. Paired swabs and tissue biopsies were collected from DFUs and both sampling techniques were compared using 16S rRNA gene sequencing.

Results

Mean bacterial abundance determined using quantitative polymerase chain reaction (qPCR) was significantly lower in tissue biopsies (p = 0.03). The mean number of reads across all samples was significantly higher in wound swabs \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \Big(\overline{X} $$\end{document}(X¯ = 32,014) compared to tissue (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overline{X} $$\end{document}X¯ = 15,256, p = 0.001). Tissue biopsies exhibited greater overall diversity of bacteria relative to swabs (Shannon’s H diversity p = 0.009). However, based on a presence/absence analysis of all paired samples, the frequency of occurrence of bacteria from genera of known and potential pathogens was generally higher in wound swabs than tissue biopsies. Multivariate analysis identified significantly different bacterial communities in swabs compared to tissue (p = 0.001). There was minimal correlation between paired wound swabs and tissue biopsies in the number and types of microorganisms. RELATE analysis revealed low concordance between paired DFU swab and tissue biopsy samples (Rho = 0.043, p = 0.34).

Conclusions

Using 16S rRNA gene sequencing this study identifies the potential for using less invasive swabs to recover high relative abundances of known and potential pathogen genera from DFUs when compared to the gold standard collection method of tissue biopsy.

Frequency and Antimicrobial Susceptibility Patterns of Diabetic Foot Infection of Patients from Bandar Abbas District, Southern Iran

Diabetic foot infection is among the most common complications of diabetes mellitus which significantly causes hospitalization and is the most prevalent etiology of nontraumatic amputation worldwide. The current study aimed at assessing the frequency and antimicrobial susceptibility patterns of diabetic foot infection of patients from the Bandar Abbas area, in the south of Iran. In this study, a total of 83 diabetic patients with diabetic infected foot wounds referring to Shahid Mohammadi Hospital, Bandar Abbas, from 2017 to 2018 were assessed. Samples were obtained from wound sites and evaluated by aerobic culture and also an antibiogram test for antibiotic susceptibility. Factors including age, sex, type of diabetes, the medication used for diabetes, previous history of diabetic foot infection, duration of wound incidence, fever, and laboratory indices were recorded for each subject. The most prevalent detected bacteria were Escherichia coli (20.5%), Enterococcus sp. (16.9%), Klebsiella sp. (12%), Staphylococcus aureus (8.4%), Enterobacter sp. (7.2%), and Acinetobacter sp. (6%). The results of antibiogram tests revealed the most and the least antibiotic sensitivity for E. coli sp. as meropenem and ciprofloxacin, for Enterococcus sp. as gentamicin and ciprofloxacin, for Klebsiella sp. as amikacin and cotrimoxazole, and for Enterobacter sp. as cotrimoxazole and both amikacin and ciprofloxacin. Staphylococcus aureus was sensitive to vancomycin and doxycycline, and Acinetobacter sp. was 100% resistant to all antibiotics except amikacin and gentamycin. A significant statistical association was found between the C-reactive protein and the patients' diabetic foot infection organisms (P=0.019). Findings of the study revealed E. coli sp. as the most common bacteria which are infecting the foot lesions in the studied population. The highest antibiotic susceptibility was seen for vancomycin, linezolid, and carbapenem.

Principles and practice of antibiotic stewardship in the management of diabetic foot infections

PURPOSE OF REVIEW

Systemic antibiotic therapy in persons with a diabetic foot infection (DFI) is frequent, increasing the risk of promoting resistance to common pathogens. Applying principles of antibiotic stewardship may help avoid this problem.

RECENT FINDINGS

We performed a systematic review of the literature, especially seeking recently published studies, for data on the role and value of antibiotic stewardship (especially reducing the spectrum and duration of antibiotic therapy) in community and hospital populations of persons with a DFI.

SUMMARY

We found very few publications specifically concerning antibiotic stewardship in persons with a DFI. The case-mix of these patients is substantial and infection plays only one part among several chronic problems. As with other types of infections, attempting to prevent infections and avoiding or reducing the spectrum and duration of antibiotic therapy are perhaps the best ways to reduce antibiotic prescribing in the DFI population. The field is complex and necessitates knowledge over the current scientific literature and clinical experience. On a larger scale, clinical pathways, guidelines, and recommendations are additionally supportive.

Admission Time Deep Swab Specimens Compared With Surgical Bone Sampling in Hospitalized Individuals With Diabetic Foot Osteomyelitis and Soft Tissue Infection

Whether deep swab cultures taken at admission reliably identify pathogens compared to surgical bone specimens in hospitalized individuals with diabetic foot osteomyelitis and soft tissue infection is unclear. Comparison of microbiological isolates between a deep wound swab (DWS) taken at the time of admission through the actively infected, discharging ulcer probing to the bone and the subsequent surgical bone sample (SBS) taken during surgical debridement was made. A total of 63 subjects (age 60.8 ± 13.5 years, 75% male, 80% Type 2 diabetes, HbA1C 8.9%±2.2%) were included. The proportion of Gram-positive (DWS 49% v SBS 52%) and Gram-negative (DWS 60% v SBS 60%) isolates was similar between the techniques. However, the overall concordance of isolates between the two techniques was only fair (κ=0.302). The best concordance was observed for Staphylococcus aureus (κ=0.571) and MRSA (κ=0.644). There was a correlation between number of isolates in SBS with prior antibiotic therapy of any duration (r= -0.358, p=0.005) and with the duration of ulceration (r=0.296, p=0.045); no clinical correlations were found for DWS. Prior antibiotic therapy (p=0.03) and duration of ulceration <8 weeks (p=0.025) were predictive of negative growth on SBS. In conclusion, we found only a fair concordance between deep wound swabs acquired at admission and surgical bone specimens in those presenting with a severe diabetic foot infection and features of osteomyelitis. Ensuring early surgical debridement of all infected tissue and obtaining bone specimens should be considered a clinical priority, which may also reduce the likelihood of negative growth on SBS.

Comparative Microbiological and Whole-Genome Analysis of Staphylococcus aureus Populations in the Oro-Nasal Cavities, Skin and Diabetic Foot Ulcers of Patients With Type 2 Diabetes Reveals a Possible Oro-Nasal Reservoir for Ulcer Infection

Patients with type 2 diabetes are at higher risk for periodontal disease and diabetic foot ulcer infections (DFUIs), the latter of which are predominantly caused by staphylococcal bacteria. Staphylococci have also been detected in the mouth, nose and gums (the oro-nasal cavity) of patients with periodontal disease and can move between the mouth and nose. The present study investigated if the oro-nasal cavity and/or periodontal pockets (PPs) in diseased gum tissue can provide a microbial reservoir for DFUIs. Eighteen patients with type 2 diabetes and at least three natural teeth (13 patients with ulcers and 5 patients without ulcers) underwent non-invasive microbiological sampling of PP, oro-nasal, skin and ulcer sites. Staphylococci were recovered using selective chromogenic agar, definitively identified and subjected to DNA microarray profiling, whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Staphylococcus aureus and Staphylococcus epidermidis were recovered from both the oro-nasal and ulcer sites of 6/13 and 5/13 patients with ulcers, respectively. Molecular typing based on the staphylococcal protein A (spa) gene and DNA microarray profiling indicated that for each patient investigated, S. aureus strains from oro-nasal and ulcer sites were identical. Comparative cgMLST confirmed that isolates from multiple anatomical sites of each individual investigated grouped into closely related, patient-distinct clusters (Clusters 1-7). Isolates belonging to the same cluster exhibited an average of 2.9 allelic differences (range 0-11). In contrast, reference genomes downloaded from GenBank selected as representatives of each sequence type identified in the present study exhibited an average of 227 allelic differences from the most closely related isolate within each cluster.

Microbial Community Distribution and Core Microbiome in Successive Wound Grades of Individuals with Diabetic Foot Ulcers

Diabetic foot ulcer (DFU) is a major complication of diabetes with high morbidity and mortality rates. The pathogenesis of DFUs is governed by a complex milieu of environmental and host factors. The empirical treatment is initially based on wound severity since culturing and profiling the antibiotic sensitivity of wound-associated microbes is time-consuming. Hence, a thorough and rapid analysis of the microbial landscape is a major requirement toward devising evidence-based interventions. Toward this, 122 wound (100 diabetic and 22 nondiabetic) samples were sampled for their bacterial community structure using both culture-based and next-generation 16S rRNA-based metagenomics approach. Both the approaches showed that the Gram-negative microbes were more abundant in the wound microbiome. The core microbiome consisted of bacterial genera, including Alcaligenes, Pseudomonas, Burkholderia, and Corynebacterium in decreasing order of average relative abundance. Despite the heterogenous nature and extensive sharing of microbes, an inherent community structure was apparent, as revealed by a cluster analysis based on Euclidean distances. Facultative anaerobes (26.5%) were predominant in Wagner grade 5, while strict anaerobes were abundant in Wagner grade 1 (26%). A nonmetric dimensional scaling analysis could not clearly discriminate samples based on HbA1c levels. Sequencing approach revealed the presence of major culturable species even in samples with no bacterial growth in culture-based approach. Our study indicates that (i) the composition of core microbial community varies with wound severity, (ii) polymicrobial species distribution is individual specific, and (iii) antibiotic susceptibility varies with individuals. Our study suggests the need to evolve better-personalized care for better wound management therapies.IMPORTANCE Chronic nonhealing diabetic foot ulcers (DFUs) are a serious complication of diabetes and are further exacerbated by bacterial colonization. The microbial burden in the wound of each individual displays diverse morphological and physiological characteristics with unique patterns of host-pathogen interactions, antibiotic resistance, and virulence. Treatment involves empirical decisions until definitive results on the causative wound pathogens and their antibiotic susceptibility profiles are available. Hence, there is a need for rapid and accurate detection of these polymicrobial communities for effective wound management. Deciphering microbial communities will aid clinicians to tailor their treatment specifically to the microbes prevalent in the DFU at the time of assessment. This may reduce DFUs associated morbidity and mortality while impeding the rise of multidrug-resistant microbes.

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.

Management of diabetic foot infections in the light of recent literature and new international guidelines

Introduction: In May 2019 the International Working Group on the Diabetic Foot (IWGDF) launched their quadrennially updated guidelines on the management of diabetic foot infections (DFIs). Concomitantly, the number of new publications regarding DFI increased.Areas covered: The IWGDF committee developed and addressed key questions and produced evidence-based recommendations related to diagnosing and treating DFIs. This narrative review provides an overview of this new guideline and also of other recently published literature in the field of DFIs.Expert opinion: The 2019 IWGDF guidelines provide an authoritative, international, evidence-based approach to diagnosing and treating DFIs. The 27 recommendations are supported by systematic reviews of both diagnosis and interventions. Our review of this guideline, along with other recent publications in the field, allows us to offer state-of-the-art guidance for caring for these difficult infections. As the evidence base for management of DFIs remains suboptimal, we need further research to improve the management of DFIs.

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.

Optimization of the antibiotic management of diabetic foot infections: protocol for two randomized controlled trials

BACKGROUND

Few studies have addressed the appropriate duration of antibiotic therapy for diabetic foot infections (DFI) with or without amputation. We will perform two randomized clinical trials (RCTs) to reduce the antibiotic use and associated adverse events in DFI.

METHODS

We hypothesize that shorter durations of postdebridement systemic antibiotic therapy are noninferior (10% margin, 80% power, alpha 5%) to existing (long) durations and we will perform two unblinded RCTs with a total of 400 DFI episodes (randomization 1:1) from 2019 to 2022. The primary outcome for both RCTs is remission of infection after a minimal follow-up of 2 months. The secondary outcomes for both RCTs are the incidence of adverse events and the overall treatment costs. The first RCT will allocate the total therapeutic amputations in two arms of 50 patients each: 1 versus 3 weeks of antibiotic therapy for residual osteomyelitis (positive microbiological samples of the residual bone stump); or 1 versus 4 days for remaining soft tissue infection. The second RCT will randomize the conservative approach (only surgical debridement without in toto amputation) in two arms with 50 patients each: 10 versus 20 days of antibiotic therapy for soft tissue infections; and 3 versus 6 weeks for osteomyelitis. All participants will have professional wound debridement, adequate off-loading, angiology evaluation, and a concomitant surgical, re-educational, podiatric, internist and infectiology care. During the surgeries, we will collect tissues for BioBanking and future laboratory studies.

DISCUSSION

Both parallel RCTs will respond to frequent questions regarding the duration of antibiotic use in the both major subsets of DFIs, to ensure the quality of care, and to avoid unnecessary excesses in terms of surgery and antibiotic use.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04081792. Registered on 4 September 2019.

Comparative Microbiological and Whole-Genome Analysis of Staphylococcus aureus Populations in the Oro-Nasal Cavities, Skin and Diabetic Foot Ulcers of Patients With Type 2 Diabetes Reveals a Possible Oro-Nasal Reservoir for Ulcer Infection

Patients with type 2 diabetes are at higher risk for periodontal disease and diabetic foot ulcer infections (DFUIs), the latter of which are predominantly caused by staphylococcal bacteria. Staphylococci have also been detected in the mouth, nose and gums (the oro-nasal cavity) of patients with periodontal disease and can move between the mouth and nose. The present study investigated if the oro-nasal cavity and/or periodontal pockets (PPs) in diseased gum tissue can provide a microbial reservoir for DFUIs. Eighteen patients with type 2 diabetes and at least three natural teeth (13 patients with ulcers and 5 patients without ulcers) underwent non-invasive microbiological sampling of PP, oro-nasal, skin and ulcer sites. Staphylococci were recovered using selective chromogenic agar, definitively identified and subjected to DNA microarray profiling, whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Staphylococcus aureus and Staphylococcus epidermidis were recovered from both the oro-nasal and ulcer sites of 6/13 and 5/13 patients with ulcers, respectively. Molecular typing based on the staphylococcal protein A (spa) gene and DNA microarray profiling indicated that for each patient investigated, S. aureus strains from oro-nasal and ulcer sites were identical. Comparative cgMLST confirmed that isolates from multiple anatomical sites of each individual investigated grouped into closely related, patient-distinct clusters (Clusters 1-7). Isolates belonging to the same cluster exhibited an average of 2.9 allelic differences (range 0-11). In contrast, reference genomes downloaded from GenBank selected as representatives of each sequence type identified in the present study exhibited an average of 227 allelic differences from the most closely related isolate within each cluster.

Molecular Imaging of Diabetic Foot Infections: New Tools for Old Questions

Diabetic foot infections (DFIs) are a common, complex, and costly medical problem with increasing prevalence. Diagnosing DFIs is a clinical challenge due to the poor specificity of the available methods to accurately determine the presence of infection in these patients. However, failure to perform an opportune diagnosis and provide optimal antibiotic therapy can lead to higher morbidity for the patient, unnecessary amputations, and increased healthcare costs. Novel developments in bacteria-specific molecular imaging can provide a non-invasive assessment of the infection site to support diagnosis, determine the extension and location of the infection, guide the selection of antibiotics, and monitor the response to treatment. This is a review of recent research in molecular imaging of infections in the context of DFI. We summarize different clinical and preclinical methods and the translational implications aimed to improve the care of patients with DFI.

Diabetic Foot Ulcers: Current Advances in Antimicrobial Therapies and Emerging Treatments

Diabetic foot ulcers (DFUs) are very important diabetes-related lesions that can lead to serious physical consequences like amputations of limbs and equally severe social, psychological, and economic outcomes. It is reported that up to 25% of patients with diabetes develop a DFU in their lifetime, and more than half of them become infected. Therefore, it is essential to manage infection and ulcer recovery to prevent negatives outcomes. The available information plays a significant role in keeping both physicians and patients aware of the emerging therapies against DFUs. The purpose of this review is to compile the currently available approaches in the managing and treatment of DFUs, including molecular and regenerative medicine, antimicrobial and energy-based therapies, and the use of plant extracts, antimicrobial peptides, growth factors, ozone, devices, and nano-medicine, to offer an overview of the assessment of this condition.

Non-antibiotic antimicrobial interventions and antimicrobial stewardship in wound care

Control of wound infection today relies largely on antibiotics, but the continual emergence of antibiotic-resistant microorganisms threatens a return to the pre-antibiotic era when physicians used antiseptics to prevent and manage infection. Some of those antiseptics are still used today, and others have become available. A diverse variety of non-antibiotic antimicrobial interventions are found on modern formularies. Unlike the mode of action of antibiotics, which affect specific cellular target sites of pathogens, many non-antibiotic antimicrobials affect multiple cellular target sites in a non-specific way. Although this reduces the likelihood of selecting for resistant strains of microorganisms, some have emerged and cross-resistance between antibiotics and antiseptics has been detected. With the prospect of a post-antibiotic era looming, ways to maintain and extend our antimicrobial armamentarium must be found. In this narrative review, current and emerging non-antibiotic antimicrobial strategies will be considered and the need for antimicrobial stewardship in wound care will be explained.

Correlation between superficial and intra-operative specimens in diabetic foot infections: results of a cross-sectional Tunisian study

Objective

To determine the correlation between superficial, and intra-operative specimens in diabetic foot infections (DFIs).

Methods

We conducted a cross-sectional study in patients with DFIs hospitalized in a Tunisian teaching hospital. Superficial specimens were collected for all patients, and intra-operative specimens were collected in operated patients. The specimens were processed using standard microbiology techniques. Antimicrobial susceptibility testing was carried out according to the protocol established by the European Committee on Anti-microbial Susceptibility Testing. Intra-operative and superficial specimens were considered correlated if they isolated the same microorganism(s), or if they were both negative.

Results

One hundred twelve patients, 81 males and 31 females, mean age 56 years, were included. Superficial samples were positive in 77% of cases, and isolated 126 microorganisms. Among the positive samples, 71% were monomicrobial. The most frequently isolated microorganisms were Enterobacteriaceae (53%), followed by streptococci (21%) and Staphylococcus aureus (17%). Nine microorganisms (7%) were multi-drug resistant. Intra-operative samples were positive in 93% of cases. Superficial specimens were correlated to intra-operative specimens in 67% of cases. Initial antibiotic therapy was appropriate in 70% of cases. The lower-extremity amputation and the mortality rates were 41% and 1%, respectively.

Conclusion

In our study, DFIs were most frequently caused by Enterobacteriaceae and superficial specimens were correlated to intra-operative specimens in only two thirds of cases. Clinicians should emphasize on the systematic practice of intraoperative specimens in all patients with DFIs treated surgically, while well-performed superficial specimens could be useful for prescribing appropriate antibiotic therapy in other patients.

Co-occurrence of Anaerobes in Human Chronic Wounds

Chronic wounds are wounds that have failed to heal after 3 months of appropriate wound care. Previous reports have identified a diverse collection of bacteria in chronic wounds, and it has been postulated that bacterial profile may contribute to delayed healing. The purpose of this study was to perform a microbiome assessment of the Wound Healing and Etiology (WE-HEAL) Study cohort, including underlying comorbidities less commonly studied in the context of chronic wounds, such as autoimmune diseases, and investigate possible relationships of the wound microbiota with clinical healing trends. We examined chronic wound specimens from 60 patients collected through the WE-HEAL Study using 16S ribosomal RNA gene sequencing. A group of co-occurring obligate anaerobes was identified from taxonomic analysis guided by Dirichlet multinomial mixtures (DMM) modeling. The group includes members of the Gram-positive anaerobic cocci (GPAC) of the Clostridia class (i.e., Anaerococcus, Finegoldia, and Peptoniphilus) and additional strict anaerobes (i.e., Porphyromonas and Prevotella). We showed that the co-occurring group of obligate anaerobes not only co-exists with commonly identified wound species (such as Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas, Corynebacterium, and Streptococcus), but importantly, they could also predominate the wound microbiota. Furthermore, examination of clinical comorbidities of the WE-HEAL specimens showed that specific obligate and facultative anaerobes were significantly reduced in wounds presented with autoimmune disease. With respect to future healing trends, no association with the wound microbiome community or the abundance of individual wound species could be established. In conclusion, we identified a co-occurring obligate anaerobic community type that predominated some human chronic wounds and underrepresentation of anaerobes in wounds associated with autoimmune diseases. Possible elucidation of host environments or key factors that influence anaerobe colonization warrants further investigation in a larger cohort.

Risk Factors for Below-the-Knee Amputation in Diabetic Foot Osteomyelitis After Minor Amputation

BACKGROUND

Below-the-knee amputation (BKA) can be a detrimental outcome of diabetic foot osteomyelitis (DFO). Ideal treatment of DFO is controversial, but studies suggest minor amputation reduces the risk of BKA. We evaluated risk factors for BKA after minor amputation for DFO.

METHODS

This is a retrospective cohort of patients discharged from Denver Health Medical Center from February 1, 2012, through December 31, 2014. Patients who underwent minor amputation for diagnosis of DFO were eligible for inclusion. The outcome evaluated was BKA in the 6 months after minor amputation.

RESULTS

Of 153 episodes with DFO that met the study criteria, 11 (7%) had BKA. Failure to heal surgical incision at 3 months (P < .001) and transmetatarsal amputation (P = .009) were associated with BKA in the 6 months after minor amputation. Peripheral vascular disease was associated with failure to heal but not with BKA (P = .009). Severe infection, bacteremia, hemoglobin A_1c, and positive histopathologic margins of bone and soft tissue were not associated with BKA. The median antibiotic duration was 42 days for positive histopathologic bone resection margin (interquartile range, 32-47 days) and 16 days for negative margin (interquartile range, 8-29 days). Longer duration of antibiotics was not associated with lower risk of BKA.

CONCLUSIONS

Patients who fail to heal amputation sites in 3 months or who have transmetatarsal amputation are at increased risk for BKA. Future studies should evaluate the impact of aggressive wound care or whether failure to heal is a marker of another variable.

Remission in diabetic foot infections: Duration of antibiotic therapy and other possible associated factors

AIM

To determine the most appropriate duration of antibiotic therapy for diabetic foot infections (DFIs).

METHODS

Using a clinical pathway for adult patients with DFIs (retrospective cohort analysis), we created a cluster-controlled Cox regression model to assess factors related to remission of infection, emphasizing antibiotic-related variables. We excluded total amputations as a result of DFI and DFI episodes with a follow-up time of <2 months.

RESULTS

Among 1018 DFI episodes in 482 patients, we identified 392 episodes of osteomyelitis, 626 soft tissue infections, 246 large abscesses, 322 episodes of cellulitis and 335 episodes of necrosis; 313 cases involved revascularization. Patients underwent surgical debridement for 824 episodes (81%), of which 596 (59%) required amputation. The median total duration of antibiotic therapy was 20 days. After a median follow-up of 3 years, 251 of the episodes (24.7%) were followed by ≥1 additional episode(s). Comparing patients with and without additional episodes, risk of recurrence was lower in those who underwent amputation, had type 1 diabetes, or underwent revascularization. On multivariate analysis including the entire study population, risk of remission was inversely associated with type 1 diabetes (hazard ratio [HR] 0.3, 95% confidence interval [CI] 0.2-0.6). Neither duration of antibiotic therapy nor parenteral treatment affected risk of recurrence (HR 1.0, 95% CI 0.99-1.01 for both). Similarly, neither >3 weeks versus <3 weeks of therapy, nor >1 week versus <1 week of intravenous treatment affected recurrence. In stratified analyses for both soft tissue DFIs or osteomyelitis separately, we did not observe associations of antibiotic duration with microbiological or clinical recurrences of DFI. The HRs were 1.0 (95% CI 0.6-1.8) for an antibiotic duration >3 weeks overall and 0.6 (95% CI 0.2-1.3) for osteomyelitis cases only. Plotting of duration of antibiotic therapy failed to identify any optimal threshold for preventing recurrences.

CONCLUSIONS

Our analysis found no threshold for the optimal duration or route of administration of antibiotic therapy to prevent recurrences of DFI. These limited data might support possibly shorter treatment duration for patients with DFI.

Performance of the automated multiplex PCR Unyvero implant and tissue infections system in the management of diabetic foot osteomyelitis

AIM

We evaluated the performance of Unyvero implant and tissue infections system (ITI) application (Curetis) to diagnose Diabetic Foot Osteomyelitis (DFOM).

PATIENTS & METHODS

The study was conducted in the Diabetic Foot reference center of Nîmes University Hospital (France) from 1 December 2016 to 31 May 2017. We compared the Unyvero ITI PCR to conventional culture and alternative molecular approaches.

RESULTS

A total of 79 patients with DFOM were included: 177 microorganisms were isolated by culture, 146 detected by PCR, resulting in a concordance level of 66.7% (65.0-68.4). Discrepant results were obtained for 45 samples, with 59 microorganisms being detected by PCR only (18 samples) or by culture only (27 samples).

CONCLUSION

Unyvero ITI PCR represents an interesting additional diagnosis solution to manage DFOM.

Epidemiology of Diabetic Foot Infection in the Metro-Detroit Area With a Focus on Independent Predictors for Pathogens Resistant to Recommended Empiric Antimicrobial Therapy

Background

The polymicrobial nature of diabetic foot infection (DFI) and the emergence of antimicrobial resistance have complicated DFI treatment. Current treatment guidelines for deep DFI recommend coverage of methicillin-resistant Staphylococcus aureus (MRSA) and susceptible Enterobacteriaceae. This study aimed to describe the epidemiology of DFI and to identify predictors for DFI associated with multidrug-resistant organisms (MDROs) and pathogens resistant to recommended treatment (PRRT).

Methods

Adult patients admitted to Detroit Medical Center from January 2012 to December 2015 with DFI and positive cultures were included. Demographics, comorbidities, microbiological history, sepsis severity, and antimicrobial use within 3 months before DFI were obtained retrospectively. DFI-PRRT was defined as a DFI associated with a pathogen resistant to both vancomycin and ceftriaxone. DFI-MDRO pathogens included MRSA in addition to PRRT.

Results

Six-hundred forty-eight unique patients were included, with a mean age of 58.4 ± 13.7 years. DFI-MDRO accounted for 364 (56%) of the cohort, and 194 (30%) patients had DFI-PRRT. Independent predictors for DFI-PRRT included history of PRRT in a diabetic foot ulcer, antimicrobial exposure in the prior 90 days, peripheral vascular disease, and chronic kidney disease. Long-term care facility residence was independently associated with DFI due to ceftriaxone-resistant Enterobacteriaceae, and recent hospitalization was an independent predictor of DFI due to vancomycin-resistant Enterococcus.

Conclusions

An unexpectedly high prevalence of DFI-PRRT pathogens was identified. History of the same pathogen in a prior diabetic foot ulcer and recent antimicrobial exposure were independent predictors of DFI-PRRT and should be considered when selecting empiric DFI therapy.

Classification, microbiology and treatment of diabetic foot infections

Diabetic foot ulcers (DFUs) are a common complication of type-1 and type-2 diabetes. About 10-15% of patients with diabetes develop foot ulcers. A validated foot ulcer classification system that will support the development of treatment strategis is necessary for clinicians managing DFUs. More than 10 classification systems have been described by researchers. Another important aspect of the management of DFUs is the proper identification of causative pathogens that trigger infections. While conventional diagnostic methods, such as swabs, cultures and biopsies are more widely used, novel molecular techniques have been exploring bacterial identification and quantification. Knowledge of the microbial aetiologies in diabetic foot infections, and understanding of antibiotic resistance, is critical for the effective management and treatment of these infected wounds. Initial antibiotic regimens are usually selected empirically. A set of common principles may help avoid selecting either an unnecessarily broad or inappropriately narrow antibiotic treatment regimen. In this review we provide a comprehensive summary and description of classification systems of diabetic foot infections, and a comprehensive discussion of microbiology.

Exploring the Microbiota of Diabetic Foot Infections With Culturomics

The purpose of this prospective observational study was to evaluate the richness and diversity of bacteria in samples from diabetic foot infections using a culturomics approach. Bacterial culture findings from wound samples were analyzed together with clinical characteristics and treatment outcomes. We included 43 patients admitted to a French referral center with a moderate to severe diabetic foot infection. The 30,000 colonies identified yielded 53 different bacterial species. The global α-Shannon diversity was 3.34 and the bacterial richness per patient was 4 ± 2. Of all the identified bacterial species, 19 (35.8%) had never been previously cultured or identified by molecular methods from diabetic foot ulcers. Most of the samples were polymicrobial (N = 38; 88.3%). Of all the isolated species, the most prevalent were Staphylococcus aureus (N = 28; 52.8%), Enterococcus faecalis (N = 24; 45.2%), Enterobacter cloacae (N = 12; 22.6%), Staphylococcus lugdunensis (N = 10; 18.7%), Staphylococcus epidermidis (N = 6; 11.3%), Proteus mirabilis (N = 6; 11.3%), and Finegoldia magna (N = 5; 9.4%). The only factor associated with wound improvement after a 1-month follow-up was the presence of E. faecalis (p = 0.012) when compared with patients without wound improvement. This study confirms the complementary role of culturomics in the exploration of complex microbiota. Further studies on a larger scale are needed to fully understand the clinical importance of the microbiota of diabetic foot infections.

A randomized, controlled study to investigate the efficacy and safety of a topical gentamicin-collagen sponge in combination with systemic antibiotic therapy in diabetic patients with a moderate or severe foot ulcer infection

BACKGROUND

An adjunctive topical therapy with gentamicin-sponges to systemic antibiotic therapy might improve the healing of infected diabetic foot ulcers (DFUI).

METHODS

Single-center, investigator-blinded pilot study, randomizing (1:1) the gentamicin-sponge with systemic antibiotic versus systemic antibiotics alone for patients with DFUI.

RESULTS

We included 88 DFUI episodes with 43 patients in the gentamicin-sponge arm and 45 in the control arm. Overall, 64 (64/88; 73%) witnessed total clinical cure, 13 (15%) significant improvement, and 46 (52%) showed total eradication of all pathogens at the final visit. Regarding final clinical cure, there was no difference in favour of the gentamicin-sponges (26/45 vs. 31/43; p = 0.16). However, the gentamicin-sponge arm tended to a more rapid healing. In multivariate analysis adjusting for the case-mix, the variable "gentamicin-sponge" was not significantly associated with "cure and improvement". Gentamicin-sponges were very well tolerated, without any attributed adverse events.

CONCLUSIONS

The gentamicin-sponge was very well tolerated, but did not significantly influence overall cure.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT01951768 ). Date 2 April 2013.

Diabetic Foot Infections: Update on Management

PURPOSE OF REVIEW

Diabetic foot infections (DFIs) are common in patients with diabetes mellitus complicated by foot ulcers and can be classified in different categories based on their severity. In this report, we present the diagnosis and management of DFIs according to their classification.

RECENT FINDINGS

While appropriate antibiotic regiments and surgical techniques for the treatment of DFIs are well established, new technologies and techniques for example in medical imaging, wound care modalities, and supplementary therapy approaches show potentially promising results in preventing DFIs. As with every complex disease, fine tuning DFI management can be challenging as it requires careful evaluation of different parameters. It demands timely action, close collaboration of different specialties, and patient cooperation.