Diabetic foot infections: the role of microbiology and antibiotic treatment

Variation in Systemic Antibiotic Treatment for Diabetic Foot Osteomyelitis in England and Wales: A Multi-Centre Case Review

Background: Diabetic foot osteomyelitis (DFO) is a major complication and can lead to significant morbidity and mortality. Systemic antibiotic therapy is often initiated first line to achieve quiescence of infection. To perform a multi-centre case review of systemic antibiotic intervention to treat adults with DFO in England and Wales and compare with national guidelines 'Diabetic foot problems: prevention and management'. Methods: Eight centres from England and Wales retrospectively collated data from a minimum of five adults (aged ≥ 18 years) from electronic case records. All patients were treated with systemic antibiotics following a new diagnosis of DFO (1 June 2021-31 December 2021). Results: 40 patients (35 males and 5 females) were included; the mean age was 62.3 years (standard deviation (SD) 13.0). Patients commenced systemic oral 14 (35%) or intravenous 26 (65%) antibiotic therapy following a new diagnosis of DFO. Twenty-seven (67.5%) patients were medically or surgically managed in the 12-week period with clinical quiescence of infection. Twenty-one patients (52.5%) had no recurrence of DFO infection within 12 weeks; seventeen (42.5%) of these patients had clinical quiescence of infection with systemic antibiotics alone without surgical intervention and nine (22.5%) of these cases had no recurrence of DFO. There were no cases of major amputation or death. All centres showed significant in-centre variability in systemic antibiotic management; variability was reported in the clinical and quantity indicators specifically to antibiotic selection, single versus dual therapy, mode of delivery and duration of treatment. Conclusions: This case review identifies there is existing variation when treating adults with systemic antibiotics for DFO. Further national guidance is required to standardise service delivery and care to improve patient outcomes.

Commonly associated aerobic microbial pathogens and their antibiotic susceptibility profile in diabetic foot ulcers in tertiary care centre in Western Maharashtra

PURPOSE

Diabetes mellitus (DM-II) is a metabolic disorder either due to reduced insulin production or reduced insulin sensitivity. Diabetic foot ulcer (DFU) is one of the most devastating complications of DM-II. This study was performed to assess commonly isolated micro-organisms and their anti-microbial sensitivity pattern in diabetic foot ulcers in a tertiary care centre in Western Maharashtra.

METHODS

Adult patients with a known case of DM-II with foot lesions, suspected to be a Diabetic Foot Infections (DFIs) at the tertiary care hospital from Aug 2022 to Sept 2022 were included in the study. After obtaining informed written consent, pus sample was collected with sterile swab from lesion's base and submitted to Microbiology Laboratory for aerobic culture and sensitivity.

RESULTS

Out of 56 enrolled patients, 47 (83.9%) patients tested positive for bacteriological growth and there was 'no growth' in 9 (16.07%) patients at the end of 48 h of aerobic incubation. There was male preponderance and patients were in age group of 35-85 years. The most commonly isolated micro-organisms were P. aeruginosa (17.8%), followed by S. aureus (14.2%), K. pneumonia and P. mirabilis (12.5% each). The resistance markers observed was ESBL producer, AmpC producer, MBL producer, Methicillin resistance and Inducible Clindamycin Resistance (ICR).

CONCLUSION

Due to the injudicious use of antibiotics, antibiotic resistance has been increased in all types of soft tissue infections. The empirical formula for the treatment of DFIs should be decided for given geographical reasons according to antimicrobial susceptibility profile from particular geographical area or health care institute.

Risk Factors and Characteristics of Recalcitrant Osteomyelitis After Initial Surgical and Antibiotic Treatment

OBJECTIVES

To evaluate the injury, patient, and microbiological characteristics that place patients at risk for recalcitrant fracture-related infection and osteomyelitis despite appropriate initial treatment.

DESIGN

Retrospective chart review.

SETTING

Three level I trauma centers.

PATIENTS AND PARTICIPANTS

Two hundred and fifty-seven patients undergoing surgical debridement and antibiotic therapy for osteomyelitis from 2003 to 2019.

MAIN OUTCOME MEASUREMENTS

Patients were categorized as having undergone serial bone debridement if they had 2 separate procedures a minimum of 6 weeks apart with a full course of appropriate antibiotics in between. Patient records were reviewed for age, injury location, body mass index, smoking status, comorbidities, and culture results including the presence of multidrug-resistant organisms and culture-negative osteomyelitis.

RESULTS

A total of 257 patients were identified; 49% (n = 125) had a successful single course of treatment, and 51% (n = 132) required repeat debridement for recalcitrant osteomyelitis. At the index treatment for osteomyelitis, the most common organisms in both groups were methicillin-resistant (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA). There was no significant difference in incidence of polymicrobial infection between the 2 groups (25% vs. 20%, P = 0.49). The most common organisms cultured at the time of repeat saucerization remained MRSA and MSSA; however, the same organism was cultured from both the index and repeat procedures in only 28% (n = 37) of cases. Diabetic patients, intravenous drug use status, delay to diagnosis, and open fractures of the lower leg are independent risk factors for failure of initial treatment of posttraumatic osteomyelitis.

CONCLUSIONS

Successful eradication of fracture-related infection and posttraumatic osteomyelitis is difficult and fails 51% of the time despite standard surgical and antimicrobial therapy. Although MRSA and MSSA remain the most common organisms cultured, patients who fail initial treatment for osteomyelitis often do not culture the same organisms as those obtained at the index procedure.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Distribution of Causative Microorganisms in Diabetic Foot Infections: A Ten-Year Retrospective Study in a Tertiary Care Hospital in Central Malaysia

Diabetes mellitus is a global pandemic, especially in Southeast Asia. Diabetic foot infection (DFI) is a common complication of this condition and causes significant morbidity and mortality in those affected. There is a lack of locally published data on the types of microorganisms and empirical antibiotics being prescribed. This paper highlights the importance of local microorganism culture and antibiotic prescription trends among diabetic foot patients in a tertiary care hospital in central Malaysia. This is a retrospective, cross-sectional study of data taken from January 2010 to December 2019 among 434 patients admitted with diabetic foot infections (DFIs) using the Wagner classification. Patients between the ages of 58 and 68 years old had the highest rate of infection. Pseudomonas Aeruginosa, Proteus spp., and Proteus mirabilis appeared to be the most isolated Gram-negative microorganisms, and Staphylococcus aureus, Streptococcus agalactiae, and MRSA appeared to be the most common Gram-positive microorganisms. The most common empirical antibiotics prescribed were ampicillin/sulbactam, followed by ciprofloxacin and ceftazidime, and the most common therapeutic antibiotics prescribed were ampicillin/sulbactam, ciprofloxacin, and cefuroxime. This study could be immensely pertinent in facilitating future empirical therapy guidelines for treating diabetic foot infections.

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.

An Overview of Diabetic Foot Ulcers and Associated Problems with Special Emphasis on Treatments with Antimicrobials

One of the most significant challenges of diabetes health care is diabetic foot ulcers (DFU). DFUs are more challenging to cure, and this is particularly true for people who already have a compromised immune system. Pathogenic bacteria and fungi are becoming more resistant to antibiotics, so they may be unable to fight microbial infections at the wound site with the antibiotics we have now. This article discusses the dressings, topical antibacterial treatment, medications and debridement techniques used for DFU and provides a deep discussion of DFU and its associated problems. English-language publications on DFU were gathered from many different databases, such as Scopus, Web of Science, Science Direct, Springer Nature, and Google Scholar. For the treatment of DFU, a multidisciplinary approach involving the use of diagnostic equipment, skills, and experience is required. Preventing amputations starts with patient education and the implementation of new categorization systems. The microbiota involved in DFU can be better understood using novel diagnostic techniques, such as the 16S-ribosomal DNA sequence in bacteria. This could be achieved by using new biological and molecular treatments that have been shown to help prevent infections, to control local inflammation, and to improve the healing process.

The effectiveness of systemic antibiotics for osteomyelitis of the foot in adults with diabetes mellitus: a systematic review protocol

Background

Osteomyelitis of the foot is a major complication of diabetes that can be limb and life threatening. Systemic antibiotic pharmacotherapy is often used first line to eradicate infection and allow restoration of devitalised bone.

The aim is to conduct a systematic review of the effectiveness of systemic antibiotics on osteomyelitis of the foot in adults with diabetes mellitus.

Methods

A systematic review of all interventional studies treating osteomyelitis with systemic antibiotics in participants with diabetes mellitus and an ulcer of the foot below the malleoli will be conducted. Studies not available in English and in people below the age of 18 will be excluded. Study selection will follow the Patient Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA-P guidelines). The quality of the studies will be assessed using the Cochrane risk-of-bias tool (RoB 2) for all randomised controlled trials and the Newcastle–Ottawa Scale (NOS) will be used for non-randomised controlled trials. Electronic databases will be searched with no timeline restrictions.

Data Extraction

All identified references will be imported to the Rayyan Application. Studies for eligibility will be screened by two reviewers. One reviewer will perform the data extraction and quality appraisal will be conducted by two authors. If sufficient data is available, the quality will be analysed and a meta-analysis will be performed. Data synthesis will be conducted, and meta-analysis undertaken using RevMan 5.4.1 Meta-analysis software. Non-parametric data may be compared between selective intervention and outcomes.

Discussion

The results of this systematic review will identify the effectiveness of systemic antibiotic therapy on osteomyelitis of the foot in people with diabetes based on the set outcome measure criteria. The findings will establish if there are existing consistent standards or variation in practice when treating diabetic foot osteomyelitis (DFO). The study may establish if guidelines are required to standardise practice when treating DFO with systemic antibiotic therapy. This systematic review protocol will synthesise the existing evidence on the effectiveness of systemic antibiotic therapy for treating DFO.

Trial registration

International Prospective Register for Systematic Reviews (PROSPERO) number CRD42021245424.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00554-3.

Neutralizing Staphylococcus aureus Virulence with AZD6389, a Three mAb Combination, Accelerates Closure of a Diabetic Polymicrobial Wound

Nonhealing diabetic foot ulcers (DFU), a major complication of diabetes, are associated with high morbidity and mortality despite current standard of care. Since Staphylococcus aureus is the most common pathogen isolated from nonhealing and infected DFU, we hypothesized that S. aureus virulence factors would damage tissue, promote immune evasion and alter the microbiome, leading to bacterial persistence and delayed wound healing. In a diabetic mouse polymicrobial wound model with S. aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, we report a rapid bacterial proliferation, prolonged pro-inflammatory response and large necrotic lesions unclosed for up to 40 days. Treatment with AZD6389, a three-monoclonal antibody combination targeting S. aureus alpha toxin, 4 secreted leukotoxins, and fibrinogen binding cell-surface adhesin clumping factor A resulted in full skin re-epithelization 21 days after inoculation. By neutralizing multiple virulence factors, AZD6389 effectively blocked bacterial agglutination and S. aureus-mediated cell killing, abrogated S. aureus-mediated immune evasion and targeted the bacteria for opsonophagocytic killing. Neutralizing S. aureus virulence not only facilitated S. aureus clearance in lesions, but also reduced S. pyogenes and P. aeruginosa numbers, damaging inflammatory mediators and markers for neutrophil extracellular trap formation 14 days post initiation. Collectively, our data suggest that AZD6389 holds promise as an immunotherapeutic approach against DFU complications.

IMPORTANCE Diabetic foot ulcers (DFU) represent a major complication of diabetes and are associated with poor quality of life and increased morbidity and mortality despite standard of care. They have a complex pathogenesis starting with superficial skin lesions, which often progress to deeper tissue structures up to the bone and ultimately require limb amputation. The skin microbiome of diabetic patients has emerged as having an impact on DFU occurrence and chronicity. DFU are mostly polymicrobial, and the Gram-positive bacterium Staphylococcus aureus detected in more than 95% of cases. S. aureus possess a collection of virulence factors which participate in disease progression and may facilitate growth of other pathogens. Here we show in a diabetic mouse wound model that targeting some specific S. aureus virulence factors with a multimechanistic antibody combination accelerated wound closure and promoted full skin re-epithelization. This work opens promising new avenues for the treatment of DFU.

Diabetic foot ulcer, antimicrobial remedies and emerging strategies for the treatment

According to the International Diabetes Federation's 2015 study, diabetes affects over 415 million people globally (5 million of whom die each year), and the incidence of diabetes is expected to climb to over 640 million (1 in 10) by 2040. (IDF 2015). Diabetes foot ulcers (DFU) are one of the most significant diabetic health consequences. Antimicrobial treatments, such as dressings, topical therapies, medicines, drugs, debridement procedures, molecular, cellular, and gene therapies, plant extracts, antimicrobial peptides, growth factors, devices, ozone, and energy-based therapies, would be the focus of this study. Scopus, Web of Science, Bentham Science, Science Direct, and Google Scholar were among the sources used to compile the English-language publications on DFU. DFU treatment requires a multidisciplinary approach that includes the use of proper diagnostic tools, competence, and experience. To prevent amputations, this starts with patient education and the use of new categories to steer treatment. New diagnostic methods, such as the 16S ribosomal DNA sequence in bacteria, should become available to acquire a better knowledge of the microbiota in DFUs. 

Spectrum of Bacterial Infections Associated with Diabetic Ulcer Patients

Diabetic ulceration is a multi-factorial problem which is responsible for considerable morbidity threatening the health care system. By knowing the clinical profile and bio-burden on diabetic ulcer, it is highly beneficial for health treatment. The purpose of the present study was to evaluate the diversity of major bacterial etiology in diabetic ulcer patients. The different samples like pus, swab, and infected tissues were collected from diabetic ulcer patients aseptically and samples were transported through cold chain to the laboratory. The samples were cultured in nutrient agar, mannitol salt agar, macConkey agar and blood agar. Suspected colonies were biochemically confirmed for the isolation of Staphylococcus aureus, Pseudomonas aeruginosa, E.coli and Klebsiella spp. In total 150 diabetic ulcer patients suffering from diabetic foot ulcers, gangrene, burn cases and accidental ulcer cases were analyzed. However, most of the patients developed mono-microbial infection; S.aureus was the most prevalent microbe in diabetic ulcer cases, which were positive for nucA gene.

The Effects of Antimicrobial Resistance and the Compatibility of Initial Antibiotic Treatment on Clinical Outcomes in Patients With Diabetic Foot Infection

We aimed to determine pathogen microorganisms, their antimicrobial resistance patterns, and the effect of initial treatment on clinical outcomes in patients with diabetic foot infection (DFI). Patients with DFI from 5 centers were included in this multicenter observational prospective study between June 2018 and June 2019. Multivariate analysis was performed for the predictors of reinfection/death and major amputation. A total of 284 patients were recorded. Of whom, 193 (68%) were male and the median age was 59.9 ± 11.3 years. One hundred nineteen (41.9%) patients had amputations, as the minor (n = 83, 29.2%) or major (n = 36, 12.7%). The mortality rate was 1.7% with 4 deaths. A total of 247 microorganisms were isolated from 200 patients. The most common microorganisms were Staphylococcus aureus (n = 36, 14.6%) and Escherichia coli (n = 32, 13.0%). Methicillin resistance rates were 19.4% and 69.6% in S aureus and coagulase-negative Staphylococcus spp., respectively. Multidrug-resistant Pseudomonas aeruginosa was detected in 4 of 22 (18.2%) isolates. Extended-spectrum beta-lactamase-producing Gram-negative bacteria were detected in 20 (38.5%) isolates of E coli (14 of 32) and Klebsiella spp. (6 of 20). When the initial treatment was inappropriate, Klebsiella spp. related reinfection within 1 to 3 months was observed more frequently. Polymicrobial infection (p = .043) and vancomycin treatment (p = .007) were independent predictors of reinfection/death. Multivariate analysis revealed vascular insufficiency (p = .004), hospital readmission (p = .009), C-reactive protein > 130 mg/dL (p = .007), and receiving carbapenems (p = .005) as independent predictors of major amputation. Our results justify the importance of using appropriate narrow-spectrum empirical antimicrobials because higher rates of reinfection and major amputation were found even in the use of broad-spectrum antimicrobials.

Diabetic foot infection and osteomyelitis. Are deep-tissue cultures necessary?

Introduction

Diabetic foot infections (DFIs) are common and difficult to treat. The objective of this study was to compare swab and tissue cultures as indicators of appropriate treatment of DFIs.

Methods

This is a prospective study conducted during a 4-year period. All patients with DFIs and/or diabetic foot osteomyelitis (DFO) admitted to the University Hospital of Heraklion, Greece, were included. Clinical data were collected, while cultures taken with swabs and/or tissue biopsies were used as indicators of the microbiological cause and the appropriate treatment.

Results

In total, 83 individuals (62.7% males) with mean age of 72 years, were enrolled. Coexisting osteomyelitis was present in 18.1%. From tissue and pus cultures, 131 and 176 pathogens, respectively, were isolated. Gram-positive aerobes were the most common microorganisms, followed by Gram-negatives. Infection was polymicrobial in 40 (70.2%) out of 57 patients with tissue culture and in 54 (75.0%) out of 72 with pus culture. Microbiological results from tissue cultures were compatible with those from pus at a rate of 80%, while in cases of osteomyelitis concordance reached 100%. Multidrug-resistant organisms (MDROs) were isolated from 32 (24.4%) tissue and 44 (25%) pus cultures (p=0.910). Initial empirical antimicrobial treatment was considered inappropriate in 44.6% of cases.

Conclusions

A high concordance between easily taken swab cultures and those taken by biopsy was noted, especially in DFO. This was helpful for early change to appropriate treatment in cases where MDROs were isolated and empirical treatment was inappropriate. Further research is needed to confirm this observation in clinical practice.

In Vitro and In Vivo Antibiotic Capacity of Two Host Defense Peptides

Two nonamidated host defense peptides named Pin2[G] and FA1 were evaluated against three types of pathogenic bacteria: two (Staphylococcus aureus UPD13 and Pseudomonas aeruginosa UPD3) isolated from diabetic foot ulcer patients, and another (Salmonella enterica serovar Typhimurium [ATCC 14028]) from a commercial collection. In vitro experiments showed that the antimicrobial performance of the synthetic peptides Pin2[G] and FA1 was modest, although FA1 was more effective than Pin2[G]. In contrast, Pin2[G] had superior in vivo anti-infective activity to FA1 in rabbit wound infections by the diabetic foot ulcer pathogens S. aureus UPD13 and P. aeruginosa UPD3. Indeed, Pin2[G] reduced bacterial colony counts of both S. aureus UPD13 and P. aeruginosa UPD3 by >100,000-fold after 48 to 72 h on skin wounds of infected rabbits, while in similar infected wounds, FA1 had no major effects at 72 to 96 h of treatment. Ceftriaxone was equally effective versus Pseudomonas but less effective versus S. aureus infections. Additionally, the two peptides were evaluated in mice against intragastrically inoculated S. enterica serovar Typhimurium (ATCC 14028). Only Pin2[G] at 0.56 mg/kg was effective in reducing systemic (liver) infection by >67-fold, equivalent to the effect of treatment with levofloxacin. Pin2[G] showed superior immunomodulatory activity in increasing chemokine production by a human bronchial cell line and suppressing polyinosinic-polycytidylic acid (poly[I:C])-induced proinflammatory IL-6 production. These data showed that the in vitro antimicrobial activity of these peptides was not correlated with their in vivo anti-infective activity and suggest that other factors such as immunomodulatory activity were more important.

Bacterial Diversity of Diabetic Foot Ulcers: Current Status and Future Prospectives

Diabetic foot ulcers (DFUs) and diabetic foot infections (DFIs) are associated with reduced patient quality of life, lower-extremity amputation, hospitalization, and high morbidity and mortality. Diverse bacterial communities have been identified in DFUs/DFIs, playing a significant role in infection prognosis. However, due to the high heterogeneity of bacterial communities colonized in DFUs/DFIs, culture-based methods may not isolate all of the bacterial population or unexpected microorganisms. Recently, high sensitivity and specificity of DNA (metagenomics) and RNA (metatranscriptomics) technologies have addressed limitations of culture-based methods and have taken a step beyond bacterial identification. As a consequence, new advances obtained from DNA- and RNA-based techniques for bacterial identification can improve therapeutic approaches. This review evaluated the current state of play in aetiology of DFUs/DFIs on culture and molecular approaches, and discussed the impact of metagenomic and metatranscriptomic methods in bacterial identification approaches.

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.

Diabetic Foot Infection: Causative Pathogens and Empiric Antibiotherapy Considerations—The Experience of a Tertiary Center

Most moderate-to-severe diabetic foot infections (DFIs) require hospitalization with urgent surgical approach and administration of empiric antibiotherapy. To ensure optimal antibiotic coverage, regular microbiological background updates are imperative. The purpose is to characterize the microbiological profile and the antibiotic sensitivity pattern of the DFI causative pathogens isolated within a specialized DFI unit of a tertiary hospital, in order to establish evidence-based policies regarding empirical antibiotic use. A cross-sectional study was conducted. Microbiological cultures and corresponding antibiotic sensitivity tests collected from moderate-to-severe DFIs as a first approach to the hospitalized patient were retrieved and analyzed during a 12-month period. Two groups were analyzed: inpatients that had been previously followed at the diabetic foot clinic of the hospital and inpatients without a previous contact with the hospital services. A total of 125 isolates obtained from 87 patients were deemed for analysis. Globally, a predominance of Gram-positive bacteria was observed (60%). Staphylococcus aureus was the most common pathogen. The global ratio of methicillin-sensitive S aureus to methicillin-resistant S aureus (MRSA) was 1.3:1, with similar findings in both groups. According to the antibiotic sensitivity test results, and within the recommended empiric antibiotic regimens for DFI, piperacillin/tazobactam seems to be the most suitable option. Gram-positive bacteria prevail as the main isolates in DFIs. Screening for MRSA-specific risk factors is mandatory. When going for a first empiric therapy, piperacillin/tazobactam is recommended in this institution, and an anti-MRSA agent should be added early, if necessary. We encourage continuous monitoring for the bacterial prevalence in Portuguese diabetic foot centers as it is paramount for the decision making regarding DFI protocols.

Antimicrobial susceptibility pattern of aerobes in diabetic foot ulcers in a South-Indian tertiary care hospital

PURPOSE

Diabetic foot infections (DFIs) are major public health concerns. In the view of the ever increasing burden of multidrug-resistant (MDR) organisms, improving the use of antimicrobial agents (AMAs) is a national priority. Objective of the study was to determine antimicrobial susceptibility (AMS) pattern of aerobes in DFIs.

METHODS

A cross-sectional study was conducted for a period of 3 years at Department of Surgery, Kasturba hospital, Manipal, India during which, 260 diabetic foot ulcer (DFU) patients admitted in the general surgery wards were enrolled for the study. These patients' culture specimens were observed as Gram-stained smears and cultured aerobically on blood agar and MacConkey agar plates. AMS test was performed by disc diffusion technique according to Clinical and Laboratory Standards Institute (CLSI) guidelines.

RESULTS

A total of 354 microbes were isolated from the ulcer wounds of 213 diabetic foot patients, with an average of 1.7 organisms per lesion. Monomicrobial infections were less common (n=81; 31.2%) than polymicrobial infections (n=132; 50.7%). Gram-negative bacteria were the most common among the isolates (n=192; 54.2%). Aerobic Gram-positive Cocci accounted for 162 (45.8%) of all isolates. On the other hand, Staphylococcus aureus was the most frequently isolated aerobe (n=106; 29.9%) followed by Pseudomonas aeruginosa (n=91; 25.7%).

CONCLUSION

AMS data from our study recommends that doxycycline would be the appropriate choice as single drug for empirical coverage for Gram-positive organisms. The most appropriate antibiotic for Gram-negative organisms is meropenem. One of the critical observations is the presence of Acinetobacter, an MDR isolated from DFIs, which is either relatively or totally resistant to all the AMAs tested.

Skin Wound Healing Is Accelerated by a Lipid Mixture Representing Major Lipid Components of Chamaecyparis obtusa Plant Extract

In chronic nonhealing wounds, the healing process is disrupted and wounds are often infected with bacteria. About 85% of lower extremity amputations in diabetes are attributed to deep infection of foot ulcers. Therefore, infection control is critical for wound care. In this study, we analyzed lipid composition of Chamaecyparis obtusa extract, and we describe the wound-healing properties of its combination of 10 major lipid components. A 10-lipid mixture up-regulated HBD-3 and LL-37 through the olfactory receptor 2AT4 and induced phosphorylation of extracellular signal-regulated kinases and p38 mitogen-activated protein kinases in primary human keratinocytes. In addition, the 10-lipid mixture had direct bactericidal effects against Staphylococcus aureus and Streptococcus pyogenes and protected against staphylococcal α-toxin-induced keratinocyte cell death. In an animal model, the 10-lipid mixture accelerated skin wound healing and was also effective in healing wounds superinfected with S. aureus. We suggest that the 10-lipid mixture, because of its wound-healing and antimicrobial properties, can be beneficial for wound treatment.

Skin and Soft Tissue Infections

The skin is colonized by a diverse collection of microorganisms which, for the most part, peacefully coexist with their hosts. Skin and soft tissue infections (SSTIs) encompass a variety of conditions; in immunocompromised hosts, SSTIs can be caused by diverse microorganisms-most commonly bacteria, but also fungi, viruses, mycobacteria, and protozoa. The diagnosis of SSTIs is difficult because they may commonly masquerade as other clinical syndromes or can be a manifestation of systemic disease. In immunocompromised hosts, SSTI poses a major diagnostic challenge, and clinical dermatological assessment should be initially performed; to better identify the pathogen and to lead to appropriate treatment, etiology should include cultures of lesions and blood, biopsy with histology, specific microbiological analysis with special stains, molecular techniques, and antigen-detection methodologies. Here, we reviewed the epidemiology, pathophysiology, clinical presentation, and diagnostic techniques, including molecular biological techniques, used for SSTIs, with a focus on the immunocompromised host, such as patients with cellular immunodeficiency, HIV, and diabetic foot infection.

Culture-Based Screening of Aerobic Microbiome in Diabetic Foot Subjects and Developing Non-healing Ulcers

The study was carried on diabetic foot patients to deduce clinical attributes, the occurrence of the range of aerobic microbial flora and to assess their comparative in vitro susceptibility to the customarily used antimicrobials. We also studied the potential risk factors involved in the development of non-healing ulcers. A total of 87 organisms were isolated from 70 specimens, including Escherichia coli (19.5%) among the Gram-negative and Staphylococcus aureus (18.4%) among the Gram-positive as the predominant aerobes explored. Pseudomonas aeruginosa and E. coli were predominant isolates of non-healing ulcers. The antimicrobial sensitivity pattern revealed that vancomycin (100%) and amikacin (90.4%) exhibited highest sensitivity to Gram-positive cocci, while all strains of P. aeruginosa were sensitive toward imipenem (100%). The prevalent uncontrolled glycemic status, altered lipid spectra, the existence of neuropathy, and peripheral vascular disease, suggested predisposition toward the development of non-healing lesions. The study has underlined the need for continuous surveillance of bacteria and their antimicrobial sensitivity blueprints to provide the basis for empirical therapy and to minimize the risk of complications. Further, stringent clinical evaluation, and medical history will help in revealing the risk of developing non-healing status in diabetic foot ulcers.

High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice

We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA) was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.

In-vitro diagnosis of single and poly microbial species targeted for diabetic foot infection using e-nose technology

Background

Effective management of patients with diabetic foot infection is a crucial concern. A delay in prescribing appropriate antimicrobial agent can lead to amputation or life threatening complications. Thus, this electronic nose (e-nose) technique will provide a diagnostic tool that will allow for rapid and accurate identification of a pathogen.

Results

This study investigates the performance of e-nose technique performing direct measurement of static headspace with algorithm and data interpretations which was validated by Headspace SPME-GC-MS, to determine the causative bacteria responsible for diabetic foot infection. The study was proposed to complement the wound swabbing method for bacterial culture and to serve as a rapid screening tool for bacteria species identification. The investigation focused on both single and poly microbial subjected to different agar media cultures. A multi-class technique was applied including statistical approaches such as Support Vector Machine (SVM), K Nearest Neighbor (KNN), Linear Discriminant Analysis (LDA) as well as neural networks called Probability Neural Network (PNN). Most of classifiers successfully identified poly and single microbial species with up to 90% accuracy.

Conclusions

The results obtained from this study showed that the e-nose was able to identify and differentiate between poly and single microbial species comparable to the conventional clinical technique. It also indicates that even though poly and single bacterial species in different agar solution emit different headspace volatiles, they can still be discriminated and identified using multivariate techniques.

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

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

Is it possible to sanitize athletes' shoes?

CONTEXT

Footwear should be designed to avoid trauma and injury to the skin of the feet that can favor bacterial and fungal infections. Procedures and substances for sanitizing the interior of shoes are uncommon but are important aspects of primary prevention against foot infections and unpleasant odor.

OBJECTIVE

To evaluate the efficacy of a sanitizing technique for reducing bacterial and fungal contamination of footwear.

DESIGN

Crossover study.

SETTING

Mens Sana basketball team.

PATIENTS OR OTHER PARTICIPANTS

Twenty-seven male athletes and 4 coaches (62 shoes).

INTERVENTION(S)

The experimental protocol required a first sample (swab), 1/shoe, at time 0 from inside the shoes of all athletes before the sanitizing technique began and a second sample at time 1, after about 4 weeks, April 2012 to May 2012, of daily use of the sanitizing technique.

MAIN OUTCOME MEASURE(S)

The differences before and after use of the sanitizing technique for total bacterial count at 36 °C and 22 °C for Staphylococcus spp, yeasts, molds, Enterococcus spp, Pseudomonas spp, Escherichia coli , and total coliform bacteria were evaluated.

RESULTS

Before use of the sanitizing technique, the total bacterial counts at 36 °C and 22 °C and for Staphylococcus spp were greater by a factor of 5.8 (95% confidence interval [CI] = 3.42, 9.84), 5.84 (95% CI = 3.45, 9.78), and 4.78 (95% CI = 2.84, 8.03), respectively. All the other comparisons showed a reduction in microbial loads, whereas E coli and coliforms were no longer detected. No statistically significant decrease in yeasts (P = .0841) or molds (P = .6913) was recorded probably because of low contamination.

CONCLUSIONS

The sanitizing technique significantly reduced the bacterial presence in athletes' shoes.

Molecular diagnosis of Actinomadura madurae infection by 16S rRNA deep sequencing

Next-generation DNA sequencing can be used to catalog individual organisms within complex, polymicrobial specimens. Here, we utilized deep sequencing of 16S rRNA to implicate Actinomadura madurae as the cause of mycetoma in a diabetic patient when culture and conventional molecular methods were overwhelmed by overgrowth of other organisms.

Correlations between Income inequality and antimicrobial resistance

Objectives

The aim of this study is to investigate if correlations exist between income inequality and antimicrobial resistance. This study’s hypothesis is that income inequality at the national level is positively correlated with antimicrobial resistance within developed countries.

Data collection and analysis

Income inequality data were obtained from the Standardized World Income Inequality Database. Antimicrobial resistance data were obtained from the European antimicrobial Resistance Surveillance Network and outpatient antimicrobial consumption data, measured by Defined daily Doses per 1000 inhabitants per day, from the European Surveillance of antimicrobial Consumption group. Spearman’s correlation coefficient (r) defined strengths of correlations of: > 0.8 as strong, > 0.5 as moderate and > 0.2 as weak. Confidence intervals and p values were defined for all r values. Correlations were calculated for the time period 2003-10, for 15 European countries.

Results

Income inequality and antimicrobial resistance correlations which were moderate or strong, with 95% confidence intervals > 0, included the following. Enterococcus faecalis resistance to aminopenicillins, vancomycin and high level gentamicin was moderately associated with income inequality (r= ≥0.54 for all three antimicrobials). Escherichia coli resistance to aminoglycosides, aminopenicillins, third generation cephalosporins and fluoroquinolones was moderately-strongly associated with income inequality (r= ≥0.7 for all four antimicrobials). Klebsiella pneumoniae resistance to third generation cephalosporins, aminoglycosides and fluoroquinolones was moderately associated with income inequality (r= ≥0.5 for all three antimicrobials). Staphylococcus aureus methicillin resistance and income inequality were strongly associated (r=0.87).

Conclusion

As income inequality increases in European countries so do the rates of antimicrobial resistance for bacteria including E. faecalis, E. coli, K. pneumoniae and S. aureus. Further studies are needed to confirm these findings outside Europe and investigate the processes that could causally link income inequality and antimicrobial resistance.