Deep tissue biopsy vs. superficial swab culture monitoring in the microbiological assessment of limb-threatening diabetic foot infection

Wound, pressure ulcer, and burn guidelines - 3: Guidelines for the diagnosis and treatment of diabetic ulcers and gangrene, second edition

The Japanese Dermatological Association aimed to prepare a second edition of guidelines for the management of diabetic ulcer/gangrene with emphasis on the diagnosis and treatment of skin symptoms. This new edition serves as a tool to improve the quality of the diagnosis and treatment in each patient and, further, to improve the level of care for such skin conditions. All sections have been updated by collecting documents published since the publication of the first edition. In the antibacterial drug treatment for bacterial infection of ulcers, oral administration was added after consideration. In the treatment of antibacterial drugs for bacterial infection of ulcers, not only infusion but also oral administration was mentioned. In addition, clinical questions (CQs) for imaging tests for diagnosing ischemia of the limbs were newly created. The titles of some CQs were changed to conform to the actual clinical setting. (i) The content has been updated by adding and collecting documents for all sections; (ii) we have additionally included oral antibiotic treatment for bacterial infection of ulcers; (iii) we have added CQs pertaining to imaging tests for diagnosing ischemia of the limbs; and (iv) we have revised the titles of some CQs to conform to the actual clinical setting. In particular, the recommendation levels of dressing materials newly covered by Japanese national health insurance are mentioned. In addition, CQs regarding the initial treatment of electrical (CQ15) and chemical burns (CQ16), and the use of escharotomy (CQ22) have been created.

Are Deep Tissue Cultures a Reliable Alternative to Bone Biopsy for Diagnosing Diabetic Foot Osteomyelitis? A Comparative Diagnostic Study

Background: Diabetic foot osteomyelitis (DFO) is a serious complication of diabetic foot ulcers (DFUs) that contributes to high morbidity and an increased risk of lower extremity amputation. While bone biopsy cultures are considered the gold standard for identifying causative pathogens, their invasive nature limits widespread clinical use. This study evaluates the microbiological concordance between deep tissue and bone cultures in diagnosing DFO. Methods: A retrospective analysis was conducted on 107 patients with DFO who underwent simultaneous deep tissue and bone biopsy cultures. Patient demographics, ulcer classification, and microbiological culture results were recorded. The agreement between deep tissue and bone cultures was assessed to determine the diagnostic utility of deep tissue sampling. Results: The overall concordance between deep tissue and bone cultures was 51.8%. Staphylococcus aureus was the most frequently isolated pathogen in both culture types and had the highest agreement rate (44.4%). Concordance rates were lower for Gram-negative bacteria (31.9%) and other Gram-positive microorganisms (24.2%). In 21.2% of the cases, pathogens were isolated only from deep tissue cultures, while 16.5% had positive bone cultures but negative deep tissue cultures. Conclusions: Deep tissue cultures demonstrate moderate microbiological concordance with bone biopsy in the diagnosis of DFO, particularly in cases with monomicrobial Staphylococcus aureus infection. While bone biopsy remains the gold standard, deep tissue cultures may be a practical alternative when bone sampling is not feasible or for patients unsuitable for surgery. However, their limited reliability in detecting Gram-negative and polymicrobial infections underscores the need for more accurate, less invasive diagnostic tools. Future research should focus on validating molecular and advanced diagnostic methods to improve clinical decision-making and patient outcomes in DFO.

Bacterial Profile and Antimicrobial Resistance Patterns of Diabetic Foot Infections in a Major Research Hospital of Turkey

Background/Aim: Diabetic foot infection (DFI) occurs frequently in patients, followed up with diabetic foot ulcers (DFU). For this reason, antibiotic treatment is often used in patients followed with DFU. Inappropriate use of antibiotics and increasing antibiotic resistance threaten public health. We aimed to investigate the microbial spectrum and antimicrobial resistance patterns isolated from diabetic foot infections in Turkey and help clinicians to choose optimal antibiotics empirically. Materials and Methods: This study was planned as a retrospective, single-center, cross-sectional study. Two hundred sixty-two patients whose causative microorganism was isolated in culture of tissue between 1 January 2021 and 31 December 2022 were included in this study. Bacterial profile and antimicrobial resistance patterns were analyzed. Results: Four hundred thirty two isolates from 262 patients isolated in culture of tissue were evaluated. Of these microorganisms, 57.60% were Gram-negative, 41.20% were Gram-positive bacteria, and 1.2% were Candida spp. The most frequently detected Gram-positive microorganism was Staphylococcus spp. Gram-negative microorganisms were Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). Polymicrobial infections were observed in 40.5% of the patients. Methicillin-resistant Staphylococcus spp. rate was 51.3%, while extended-spectrum beta-lactamase (ESBL) resistance for E. coli was 66.7%. Conclusions: Due to increasing antibiotic resistance rates, treatment of common infections becomes more difficult. Knowledge of the microbiological profile and antibiotic resistance patterns of patients with DFIs is useful to guide empirical therapy.

Do barrier dressings reduce cardiac implantable device infection: Protocol for a randomized controlled trial (BARRIER-PROTECT)

Background

Cardiac implantable electronic device (CIED) procedures can be associated with serious complications, including infection with significant mortality and morbidity, necessitating removal of the device and prolonged hospitalization. One potential pathophysiological mechanism is pocket contamination at the time of device implantation. Therefore, steps taken to prevent contamination at this stage can potentially reduce CIED infections.The barrier dressing, an adhesive material applied to the skin, has the potential to reduce the colonization of the surgical site with host flora that can predispose to infection. There are a limited number of randomized prospective studies on barrier dressing use during various surgeries, but it has never been systematically studied in CIED implantation.

Objectives

Do Barrier Dressings Reduce Cardiac Implantable Device Infection? (BARRIER-PROTECT trial; NCT04591366) is a single-centre, prospective, double-armed, single-blinded, randomized controlled trial designed to evaluate the use of an intra-operative adhesive barrier dressing to reduce the risk of end-of-procedure pocket swab positivity. We hypothesize that adhesive draping during implant procedures will reduce the risk of contamination from the skin flora. Also, we aim to investigate if the end-of-procedure pocket swab culture positivity can be used as a potential surrogate marker of CIED infection.

Methods and Design

Patients undergoing a second or later procedure on the same device pocket (pulse generator change, lead/pocket revision or upgrade) will be enrolled. Eligible and consenting patients will be equally randomized to the use of barrier dressing or not using an automated web-based system. Patients, but not the operator, will be blinded to the arm. The person performing the pocket swabs will also be blinded. The primary endpoint is the end-of-procedure pocket swab culture positivity. The main secondary endpoint is the CIED infection rate.

Discussion

This is the first randomized controlled trial to assess the effectiveness of using a barrier adhesive draping on reducing the end-of-procedure pocket swab culture positivity. In this study, we are exploring a low-cost intervention that may significantly reduce CIED infection. Also, having a valid surrogate marker for CIED infection at the time of implant will facilitate design of future clinical trials.

Wound swabs versus biopsies to detect methicillin resistant Staphylococcus aureus in experimental equine wounds

OBJECTIVE

To compare: (1) the load and diversity of cultivatable bacterial species isolated from tissue biopsies with cultures from surface swabs, and (2) the ability of each technique to detect methicillin-resistant Staphylococcus aureus (MRSA) in a model of MRSA-infected equine wounds.

STUDY DESIGN

Experimental in vivo study.

ANIMALS

Three light-breed adult horses.

METHODS

Four 2.5 × 2.5 cm full-thickness skin wounds were created on the dorsolateral aspect of each forelimb. Five days later, each wound was inoculated with a pure culture of MRSA (ATCC 43300). One hundred microlitres of 0, 5 × 108 , 5 × 109 or 5 × 1010 colony forming units (CFU)/ml was used to inoculate each wound. Surface swabs (Levine technique) and tissue biopsy samples (3 mm punch biopsy) were obtained at 2, 7, 14, and 21 days after inoculation. Quantitative aerobic culture was performed using routine clinical techniques.

RESULTS

A similar bacterial profile was identified from the culture of each wound-sampling technique and there was moderate correlation (R = 0.49, P < .001) between the bacterial bioburdens. Agreement was fair (κ = 0.31; 95% CI, 0.129-0.505) between the sampling techniques in identification of MRSA. Methicillin-resistant Staphylococcus aureus was isolated more frequently (P = .016) from cultures of tissue biopsies (79%; 76/96) than from surface swabs (62%; 60/96).

CONCLUSION

Bacterial load and diversity did not differ between sampling techniques but MRSA was detected more often from the cultures of tissue biopsies.

CLINICAL SIGNIFICANCE

Tissue biopsy should be preferred to culture swab in wounds where MRSA is suspected.

Rapid microbiological diagnosis based on 16S rRNA gene sequencing: A comparison of bacterial composition in diabetic foot infections and contralateral intact skin

Diabetic foot infections (DFIs) represent a frequent complication of diabetes and a major cause of amputations. This study aimed to evaluate the utility of 16S rRNA gene sequencing for the rapid microbiological diagnosis of DFIs and to consistently characterize the microbiome of chronic diabetic foot ulcers (DFUs) and intact skin. Wound samples were collected by ulcer swabbing and tissue biopsy, and paired swabs of intact skin were collected from 10 patients with DFIs (five were moderately infected, and the other five were severely infected). Samples were analyzed by conventional culture and using Personal Genome Machine (PGM) 16S rRNA sequencing technology. The results showed that PGM technology detected significantly more bacterial genera (66.1 vs. 1.5 per wound sample, p < 0.001); more obligate anaerobes (52.5 vs. 0%, p < 0.001) and more polymicrobial infections (100.0 vs. 55.0%, p < 0.01) than conventional cultures. There was no statistically significant difference in bacterial richness, diversity or composition between the wound swabs and tissues (p > 0.05). The bacterial community on intact skin was significantly more diverse than that in DFUs (Chao1 value, p < 0.05; Shannon index value, p < 0.001). Gram-positive bacteria (67.6%) and aerobes (59.2%) were predominant in contralateral intact skin, while Gram-negative bacteria (63.3%) and obligate anaerobes (50.6%) were the most ubiquitous in DFUs. The most differentially abundant taxon in skin was Bacillales, while Bacteroidia was the bacterial taxon most representative of DFUs. Moreover, Fusobacterium (ρ = 0.80, p < 0.01) and Proteus (ρ = 0.78, p < 0.01) were significantly correlated with the duration of DFIs. In conclusion, PGM 16S rRNA sequencing technology could be a potentially useful technique for the rapid microbiological diagnosis of DFIs. Wound swabbing may be sufficient for sampling bacterial pathogens in DFIs compared with biopsy which is an invasive technique. The empirical use of broad-spectrum antibiotics covering Gram-negative obligate anaerobes should be considered for the treatment of moderate or severe DFIs.

Routine bacterial culture of proximal bone specimens during minor amputation in patients with diabetes-related foot infections has little clinical utility in predicting re-operation or ulcer healing

BACKGROUND

Trans-phalangeal and trans-metatarsal amputation, collectively termed 'minor amputations' are important procedures for managing infections of diabetes-related foot ulcers (DFU). Following minor amputation, international guidelines recommend a prolonged course of antibiotics if residual infected bone on intra-operative bone samples are identified, but the quality of the evidence underpinning these guidelines is low. In this study, we examined the concordance of microbiological results from proximal bone cultures compared to results from superficial wound swabs in relation to patient outcomes; with the aim of determining the utility of routinely obtaining marginal bone specimens.

METHODS

Data was retrospectively collected on 144 individuals who underwent minor amputations for infected DFU at a large Australian tertiary hospital. Concordance was identified for patients with both superficial wound swabs and intra-operative bone samples available. Patient outcomes were monitored up to 6 months post-amputation. The primary outcome was complete healing at 6 months; and secondary outcome measures included further surgery and death. Mann Whitney U testing was performed for bivariate analyses of continuous variables, Chi-Squared testing used for categorical variables and a logistic regression was performed with healing as the dependent variable.

RESULTS

A moderate-high degree of concordance was observed between microbiological samples, with 38/111 (35%) of patients having discordant wound swab and bone sample microbiology. Discordant results were not associated with adverse outcomes (67.2% with concordant results achieved complete healing compared with 68.6% patients with discordant results; P = 0.89). Revascularisation during admission (0.37 [0.13-0.96], P = 0.04) and amputation of the 5th ray (0.45 [0.21-0.94], P = 0.03) were independent risk factors for non-healing.

CONCLUSION

There was a moderate-high degree of concordance between superficial wound swab results and intra-operative bone sample microbiology in this patient cohort. Discordance was not associated with adverse outcomes. These results suggest there is little clinical utility in routinely collecting proximal bone as an adjunct to routine wound swabs for culture during minor amputation for an infected DFU.

The association between bacteria and outcome and the influence of sampling method, in people with a diabetic foot infection

Purpose

Different bacteria lead to divers diabetic foot infections (DFIs), and some bacteria probably lead to higher amputation and mortality risks. We assessed mortality and amputation risk in relation to bacterial profiles in people DFI and investigated the role of sampling method.

Methods

We included people (> 18 years) with DFI in this retrospective study (2011–2020) at a Dutch tertiary care hospital. We retrieved cultures according to best sampling method: (1) bone biopsy; (2) ulcer bed biopsy; and (3) swab. We aggregated data into a composite determinant, consisting of unrepeated bacteria of one episode of infection, clustered into 5 profiles: (1) Streptococcus and Staphylococcus aureus; (2) coagulase-negative Staphylococcus, Cutibacterium, Corynebacterium and Enterococcus; (3) gram-negative; (4) Anaerobic; and (5) less common gram-positive bacteria. We calculated Hazard Ratio’s (HR’s) using time-dependent-Cox regression for the analyses and investigated effect modification by sampling method.

Results

We included 139 people, with 447 person-years follow-up and 459 episodes of infection. Sampling method modified the association between bacterial profiles and amputation for profile 2. HR’s (95% CI’s) for amputation for bacterial profiles 1–5: 0.7 (0.39–1.1); stratified analysis for profile 2: bone biopsy 0.84 (0.26–2.7), ulcer bed biopsy 0.89 (0.34–2.3), swab 5.9*(2.9–11.8); 1.3 (0.78–2.1); 1.6 (0.91–2.6); 1.6 (0.58–4.5). HR’s (95% CI’s) for mortality for bacterial profiles 1–5: 0.89 (0.49–1.6); 0.73 (0.38–1.4); 2.6*(1.4–4.8); 1.1(0.58–2.2); 0.80(0.19–3.3).

Conclusions

In people with DFI, there was no association between bacterial profiles in ulcer bed and bone biopsies and amputation. Only in swab cultures, low-pathogenic bacteria (profile 2), were associated with a higher amputation risk. Infection with gram-negative bacteria was associated with a higher mortality risk. This study underlined the possible negative outcome of DFI treatment based on swabs cultures.

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.

Emerging Diabetic Foot Ulcer Microbiome Analysis Using Cutting Edge Technologies

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

Analysis of risk factors for multidrug-resistant organisms in diabetic foot infection

BACKGROUND

To study the bacteriological characteristics, risk factors, and treatment of multi-drug resistance (MDR) organisms in patients with diabetic foot infection.

METHODS

Patients with diabetic foot ulcer admitted to hospital from June 2018 to December 2019 (n = 180) were selected as clinical subjects. Demographic information, routine blood test, wound culture and sensitivity were collected. Risk factors of MDR bacteria were analyzed.

RESULTS

Among 180 patients with diabetic foot ulcer, 146 were positive in bacterial culture, with 84 positive in MDR bacteria. A total of 182 strains were isolated, with 104 strains being multi-drug resistant. Body mass index, glycosylated hemoglobin, fasting blood glucose, triglyceride, course of ulcer, size of ulcer, peripheral neuropathy, peripheral vascular disease, osteomyelitis, peripheral blood leukocyte count, percentage of neutrophils, and previous use of antibiotics were the related factors of infection of MDR bacteria in diabetic foot ulcer patients (P < 0.05). The leukocyte count and neutrophil ratio of MDR-bacilli were lower than those of non MDR-bacilli (P < 0.05).

CONCLUSION

The risk of MDR bacteria in diabetic foot infection is high. It is necessary to evaluate the risk of multidrug-resistant bacteria by characterizing the course of disease, metabolic control, local ulcer and other aspects in order to formulate an effective treatment plan. The decrease of leukocyte count and neutrophil ratio may be related to damage of the host immune response.

Methicillin-Resistant Staphylococcus aureus (MRSA) Infection of Diabetic Foot Ulcers at a Tertiary Care Hospital in Accra, Ghana

Aim: This study investigated the spectrum of bacteria infecting the ulcers of individuals with diabetes at the Korle Bu Teaching Hospital in Accra, Ghana, focusing on Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA), with respect to their prevalence, factors predisposing to their infection of the ulcers, and antimicrobial resistance patterns. Methodology: This cross-sectional study was conducted at The Ulcer Clinic, Department of Surgery, Korle Bu Teaching Hospital, involving 100 diabetic foot ulcer patients. The ulcer of each study participant was swabbed and cultured bacteriologically, following standard procedures. Antimicrobial susceptibility testing was done for all S. aureus isolated, using the Kirby-Bauer method. Results: In total, 96% of the participants had their ulcers infected—32.3% (n = 31) of these had their ulcers infected with one bacterium, 47.9% (n = 46) with two bacteria, 18.8% (n = 18) with three bacteria, and 1.0% (n = 1) with four bacteria. The prevalence of S. aureus and MRSA were 19% and 6%, respectively. The distribution of the other bacteria was as follows: coagulase-negative Staphylococci (CoNS) (54%), Escherichia coli (24%), Pseudomonas spp. (19%), Citrobacter koseri and Morganella morgana (12% each), Klebsiella oxytoca (11%), Proteus vulgaris (8%), Enterococcus spp. (6%), Klebsiella pneumoniae (5%), Proteus mirabilis and Enterobacter spp. (4%), Klebsiella spp. (2%), and Streptococcus spp. (1%). The resistance rates of S. aureus decreased across penicillin (100%, n = 19), tetracycline (47.4%, n = 9), cotrimoxazole (42.1%, n = 8), cefoxitin (31.6%, n = 6), erythromycin and clindamycin (26.3% each, n = 5), norfloxacin and gentamicin (15.8% each, n = 3), rifampicin (10.5%, n = 2), linezolid (5.3%, n = 1), and fusidic acid (0.0%, n = 0). The proportion of multidrug resistance was 47.4% (n = 9). Except for foot ulcer infection with coagulase-negative Staphylococci, which was protective of S. aureus infection of the ulcers (OR = 0.029, p = 0.001, 95% CI = 0.004–0.231), no predictor of S. aureus, MRSA, or polymicrobial ulcer infection was identified. Conclusions: The prevalence of S. aureus and MRSA infection of the diabetic foot ulcers were high, but lower than those of the predominant infector, coagulase-negative Staphylococci and the next highest infecting agent, E. coli. Diabetic foot ulcers’ infection with coagulase-negative Staphylococci protected against their infection with S. aureus. The prevalence of multidrug resistance was high, highlighting the need to further intensify antimicrobial stewardship programmes.

Virulence and Drug-Resistance of Staphylococcus aureus Strains Isolated from Venous Ulcers in Polish Patients

Infected chronic venous ulcers (VUs) represent a major health problem. We analysed the aerobic microbiome in the VUs, the virulence, and drug-resistance of Staphylococcus aureus (SA) strains. Swabs from 143 outpatients and inpatients Polish subjects were collected. SA strains were tested for drug sensitivity using a phenotyping method and for methicillin-resistant SA (MRSA) and macrolide-lincosamide-streptogramin B (MLSB) resistance using PCR. We analysed virulence genes, the genetic similarity of strains, and performed Staphylococcal cassette chromosome mec typing and Staphylococcal protein A typing. SA was isolated as a single one in 34.9% of cases, 31.5% paired with another pathogen, and 33.6% S. aureus combined with at least two other strains. The majority of SA isolates (68.5%) possessed the virulence lukE gene. Drug resistance was significantly common in hospitalised than in ambulatory patients (OR 3.8; 95%CI 1.8–7.91). MLSB (altogether in 19.6% isolates) were observed mostly in non-hospitalised patients (OR 9.1; 95%CI 1.17–71.02), while MRSA was detected in 11.9% of strains equally. Hospitalisation and patient’s age group (aged > 78.0 or < 54.5 years) were significant predictors of the multi-drug resistant SA (MDR-SA). Over 30% of the infected VUs were associated with multi-species biofilms and presence of potentially highly pathogenic microorganisms. Elderly hospitalised patients with chronic venous ulcers are prone to be infected with a MDR-SA.

Characterization of staphylococci sampled from diabetic foot ulcer of Jordanian patients

AIMS

The aim of this study was to isolate and characterize staphylococcal isolates from diabetic foot ulcers (DFU) in Jordanian patients.

METHODS AND RESULTS

Selected aerobic pathogens recovered from DFU specimens and patients' nares with a focus on staphylococci were investigated. Antimicrobial susceptibilities and the prevalence of methicillin-resistant staphylococci (MRS) were determined. SCCmec types and toxigenic characteristics were analysed and spa typing was performed for methicillin-resistant Staphylococcus aureus (MRSA) isolates. The relationship between toxigenic characteristics of MRSA and the Wagner ulcer grading system was statistically analysed. A total number of 87 DFU patients were recruited for the study. The DFU cultures were polymicrobial. Members of the genus Staphylococcus were the most common among DFU-associated isolates found in 48·3% (n = 42) of all patients enrolled. Coagulase-negative staphylococci (CoNS) comprised 63·3% of staphylococci isolated from DFUs predominated by Staphylococcus epidermidis in both DFU (7·6%) and nares (39·2%). Staphylococcus aureus was isolated from DFUs and nares in 14·2 and 9·8%, respectively, while 93 and 70% of these isolates were MRSA. Most of MRSA carried SCCmec type IV (76·2%) while SCCmec elements were non-typeable in most methicillin resistant coagulase negative staphylococci (MR-CoNS) (61·9%). The most frequent MRSA spa type was t386 (23·8%). Most MRSA and MR-CoNS exhibited resistance towards aminoglycosides, fluoroquinolones and macrolides and susceptibility towards vancomycin, mupirocin and linezolid. No association was found between the possession of pvl, tst, sea and hlg toxins and Wagner ulcer grading system (P value >0·05).

CONCLUSIONS

This analysis of Jordanian DFU culture demonstrated its polymicrobial nature with predominance of Staphylococcus sp.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first of its type to assess the microbiology of DFU among Jordanian patients. The results will help in the appropriate application of antimicrobial chemotherapy in the management of DFU.

Diagnostic Accuracy of Bone Culture Versus Biopsy in Diabetic Foot Osteomyelitis

OBJECTIVE

To compare the diagnostic accuracy of bone culture (microbiology) and biopsy (histology) in patients with acute or chronic diabetic foot osteomyelitis (DFO).

METHODS

This cross-sectional study involved patients for whom providers had a clinical suspicion of DFO. Two bone samples were taken: one for microbiologic testing and another for histologic testing. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated for bone culture results in relation to the probability of DFO diagnosis.

RESULTS

Fifty-two patients were included; 69% had positive bone culture results, and 90.4% had positive histology results (P = .013), and of those 90.4%, 25.5% had acute and 74.5% had chronic DFO. The sensitivity of the microbiologic bone culture result was 0.70, the specificity was 0.40, the positive predictive value was 0.92, and the negative predictive value was 0.13.

CONCLUSIONS

Histology provides more accurate diagnosis of DFO than microbiology, especially for patients with chronic DFO. These patients could be underdiagnosed because of false-negative results provided by bone culture. Providers should perform both tests to confirm the presence of DFO.

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.

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.

Imaging in Chronic Wound Diagnostics

Significance: Chronic wounds affect millions of patients worldwide, placing a huge burden on health care resources. Although significant progress has been made in the development of wound treatments, very few advances have been made in wound diagnosis. Recent Advances: Standard imaging methods like computed tomography, single-photon emission computed tomography, magnetic resonance imaging, terahertz imaging, and ultrasound imaging have been widely employed in wound diagnostics. A number of noninvasive optical imaging modalities like optical coherence tomography, near-infrared spectroscopy, laser Doppler imaging, spatial frequency domain imaging, digital camera imaging, and thermal and fluorescence imaging have emerged over the years. Critical Issues: While standard diagnostic wound imaging modalities provide valuable information, they cannot account for dynamic changes in the wound environment. In addition, they lack the capability to predict the healing outcome. Thus, there remains a pressing need for more efficient methods that can not only indicate the current state of the wound but also help determine whether the wound is on track to heal normally. Future Directions: Many imaging probes have been fabricated and shown to provide real-time assessment of tissue microenvironment and inflammatory responses in vivo. These probes have been demonstrated to noninvasively detect various changes in the wound environment, which include tissue pH, reactive oxygen species, fibrin deposition, matrix metalloproteinase production, and macrophage accumulation. This review summarizes the creation of these probes and their potential implications in wound monitoring.

Prospective evaluation of the influence of sampling method on bacterial culture results and antimicrobial selection in 52 dogs with infected wounds

OBJECTIVE

To determine the influence of sampling methods on culture results and selection of antimicrobials for treating infected wounds in dogs.

DESIGN

Prospective study from January to July 2016.

SETTING

Three private multispecialty referral centers.

ANIMALS

Fifty-two client-owned dogs with infected wounds.

INTERVENTIONS

Each wound was sampled for culture by 3 methods: swabbing prior to preparation (dirty swabs), swabbing after debridement and sterile lavage (clean swabs), and biopsy. Bacterial species and phenotypes were compared. Three clinicians unaware of patient, wound, and sampling information selected antimicrobial drugs based on culture and sensitivity reports. Antimicrobials were divided into class I, II, or III based on established guidelines. The number, highest class of antimicrobial chosen, and inter-investigator agreement were examined.

MEASUREMENTS AND MAIN RESULTS

Identical populations of bacteria were isolated for all 3 sampling techniques in only 31% of wounds. Significantly fewer bacterial species were isolated from biopsy samples (1.87 bacterial species per wound ± 1.14) than from clean swab samples (2.29 ± 1.18; P = 0.009) but not dirty swab samples (2.29 ± 1.29; P = 0.06). The recovery frequency for gram-positive bacteria was lower for biopsy compared to either swabbing technique (P = 0.001 for both comparisons). No difference was observed between clean and dirty swabbing techniques for any parameter examined. Sampling technique did not affect the proportion of wounds with anaerobic, gram-negative, or multi-drug resistant bacteria. The number (P = 0.28) and highest class of antimicrobial (P = 0.9) selected per wound did not differ between the 3 sampling techniques (P = 0.28). Clinician agreement was 83-90% depending on sampling technique.

CONCLUSION

Although there were some differences in bacteria isolated from biopsy samples compared to swab samples from infected wounds, technique did not influence the number and highest class of antimicrobial selected by clinicians. Wound debridement prior to sampling by swabbing did not alter the number or type of bacteria isolated, nor the number or the highest class of antimicrobial selected by clinicians.

Use of Focused Ultrasound (Sonication) for the Diagnosis of Infections in Neurosurgical Operations: A Systematic Review and Meta-Analysis

OBJECTIVE

Postoperative infections are one of the most devastating complications in neurosurgery, and their results are even more disastrous when biocompatible implants are involved. As the application of these implants increases, the need for a sensitive and efficient method to detect pathogens becomes imperative. The application of sonication appears to be a viable option.

METHODS

A systematic review and meta-analysis of the available literature was conducted, looking for studies reporting findings from the application of sonication following neurosurgical operations. To be included, an article needed to contain information about the material that was subjected to sonication, indication of other culture methods that were applied, and information about the isolated pathogens.

RESULTS

Six studies comprising 437 patients were included in the meta-analysis. Potential superiority of sonication over conventional microbiologic methods was found in the detection of gram-positive bacteria and in particular of coagulase-negative Staphylococcus species. A sensitivity of 0.87 and a specificity of 0.57 were calculated.

CONCLUSIONS

Regardless of the potential of sonication, it is still not a panacea. Additional studies are expected to provide significant insight into the indications and limitations of this technique.

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.

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.

Surgical Diabetic Foot Debridement: Improving Training and Practice Utilizing the Traffic Light Principle

Comprehensive management of a severe diabetic foot infection focus on clear treatment pathways. Including rapid, radical debridement of all infection in addition to intravenous antibiotics and supportive measures. However, inexperienced surgeons can often underestimate the extent of infection, risking inadequate debridement, repeated theatre episodes, higher hospital morbidity, and hospital length of stay (LOS). This study aims to assess protocolized diabetic-foot-debridement: Red-Amber-Green (RAG) model as part of a value-based driven intervention. The model highlights necrotic/infected tissue (red-zone, nonviable), followed by areas of moderate damage (amber-zone), healthy tissue (green-zone, viable). Sequential training of orthopedic surgeons supporting our emergency service was undertaken prior to introduction. We compared outcomes before/after RAG introduction (pre-RAG, n = 48; post- RAG, n = 35). Outcomes measured included: impact on number of debridement/individual admission, percentage of individuals requiring multiple debridement, and length-of-hospital-stay as a function-of-cost. All-patients fulfilled grade 2/3, stage-B, of the Texas-Wound-Classification. Those with evidence of ischemia were excluded. The pre-RAG-group were younger (53.8 ± 11.0 years vs 60.3 ± 9.2 years, P = .01); otherwise the 2-groups were matched: HbA1c, white blood cell count, and C-reactive protein. The post-RAG-group underwent significantly lower numbers of debridement's (1.1 ± 0.3 vs 1.5 ± 0.6/individual admission, P = .003); equired fewer visits to theatre (8.6% vs 38%, P = .003), their LOS was reduced (median LOS pre-RAG 36.0 vs post-RAG 21.5 days, P = .02). RAG facilitates infection clearance, fewer theatre-episodes, and shorter LOS. This protocolized-management-tools in acute severely infected diabetic foot infection offers benefits to patients and health-care-gain.

The Significant Association between Polymicrobial Diabetic Foot Infection and Its Severity and Outcomes

Background

Foot infection is a major complication of diabetes mellitus (DM) and its agents are usually polymicrobial. This study aims to describe the agent and determine the association between polymicrobial infections and the severity of diabetic foot infections (DFI) and their outcomes.

Methods

This retrospective cohort study was conducted during one year and it involved 104 patients. Their records were reviewed and assessed. The causative agents and its sensitivity pattern were noted. The results were presented as descriptive statistic and analysed.

Results

A total of 133 microorganisms were isolated with 1.28 microorganisms per lesion. The microorganism isolated were 62% (n = 83) GN (Gram-negative) and 38% (n = 50) GP (Gram-positive). GN microorganisms include Pseudomonas spp (28%), Proteus spp (11%), Klebsiella spp (8%) and E. coli (4%). Staphylococcus aureus (54%) was predominant among GP, followed by Group B Streptococci (26%) and Enterococcus spp (6%). Thirty patients (28.8%) had polymicrobial infections. The association between the quantity of microorganisms and severity of DFI was significant. Among severe DFI cases, 77.8% with polymicrobial microorganisms underwent amputation compared to 33.3% with monomicrobial infection.

Conclusion

GN microorganisms were predominantly isolated from DFIs and remained sensitive to widely used agents. Polymicrobial infections were associated with DFI severity.

Tuberculous cellulitis in an immunocompetent patient

Mycobacterial skin infections are rare, with a wide spectrum of clinical features in immunocompromised individuals. Overall, they represent <2% of all forms of extrapulmonary tuberculosis. Tuberculous cellulitis is considered a skin manifestation of miliary tuberculosis. We present a case of tuberculous cellulitis in an immunocompetent patient.

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.

Concordance in diabetic foot ulceration: a cross-sectional study of agreement between wound swabbing and tissue sampling in infected ulcers

BACKGROUND

There is inadequate evidence to advise clinicians on the relative merits of swabbing versus tissue sampling of infected diabetic foot ulcers (DFUs).

OBJECTIVES

To determine (1) concordance between culture results from wound swabs and tissue samples from the same ulcer; (2) whether or not differences in bacterial profiles from swabs and tissue samples are clinically relevant; (3) concordance between results from conventional culture versus polymerase chain reaction (PCR); and (4) prognosis for patients with an infected DFU at 12 months' follow-up.

METHODS

This was a cross-sectional, multicentre study involving patients with diabetes and a foot ulcer that was deemed to be infected by their clinician. Microbiology specimens for culture were taken contemporaneously by swab and by tissue sampling from the same wound. In a substudy, specimens were also processed by PCR. A virtual 'blinded' clinical review compared the appropriateness of patients' initial antibiotic regimens based on the results of swab and tissue specimens. Patients' case notes were reviewed at 12 months to assess prognosis.

RESULTS

The main study recruited 400 patients, with 247 patients in the clinical review. There were 12 patients in the PCR study and 299 patients in the prognosis study. Patients' median age was 63 years (range 26-99 years), their diabetes duration was 15 years (range 2 weeks-57 years), and their index ulcer duration was 1.8 months (range 3 days-12 years). Half of the ulcers were neuropathic and the remainder were ischaemic/neuroischaemic. Tissue results reported more than one pathogen in significantly more specimens than swabs {86.1% vs. 70.1% of patients, 15.9% difference [95% confidence interval (CI) 11.8% to 20.1%], McNemar's p-value < 0.0001}. The two sampling techniques reported a difference in the identity of pathogens for 58% of patients. The number of pathogens differed in 50.4% of patients. In the clinical review study, clinicians agreed on the need for a change in therapy for 73.3% of patients (considering swab and tissue results separately), but significantly more tissue than swab samples required a change in therapy. Compared with traditional culture, the PCR technique reported additional pathogens for both swab and tissue samples in six (50%) patients and reported the same pathogens in four (33.3%) patients and different pathogens in two (16.7%) patients. The estimated healing rate was 44.5% (95% CI 38.9% to 50.1%). At 12 months post sampling, 45 (15.1%) patients had died, 52 (17.4%) patients had a lower-extremity ipsilateral amputation and 18 (6.0%) patients had revascularisation surgery.

LIMITATIONS

We did not investigate the potential impact of microbiological information on care. We cannot determine if the improved information yield from tissue sampling is attributable to sample collection, sample handling, processing or reporting.

CONCLUSIONS

Tissue sampling reported both more pathogens and more organisms overall than swabbing. Both techniques missed some organisms, with tissue sampling missing fewer than swabbing. Results from tissue sampling more frequently led to a (virtual) recommended change in therapy. Long-term prognosis for patients with an infected foot ulcer was poor.

FUTURE WORK

Research is needed to determine the effect of sampling/processing techniques on clinical outcomes and antibiotic stewardship.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

CODIFI (Concordance in Diabetic Foot Ulcer Infection): a cross-sectional study of wound swab versus tissue sampling in infected diabetic foot ulcers in England

OBJECTIVE

To determine the extent of agreement and patterns of disagreement between wound swab and tissue samples in patients with an infected diabetic foot ulcer (DFU).

DESIGN

Multicentre, prospective, cross-sectional study.

SETTING

Primary and secondary care foot ulcer/diabetic outpatient clinics and hospital wards across England.

PARTICIPANTS

Inclusion criteria: consenting patients aged ≥18 years; diabetes mellitus; suspected infected DFU.

EXCLUSION CRITERIA

clinically inappropriate to take either sample.

INTERVENTIONS

Wound swab obtained using Levine's technique; tissue samples collected using a sterile dermal curette or scalpel.

OUTCOME MEASURES

Coprimary: reported presence, and number, of pathogens per sample; prevalence of resistance to antimicrobials among likely pathogens. Secondary: recommended change in antibiotic therapy based on blinded clinical review; adverse events; sampling costs.

RESULTS

400 consenting patients (79% male) from 25 centres.Most prevalent reported pathogens were Staphylococcus aureus (43.8%), Streptococcus (16.7%) and other aerobic Gram-positive cocci (70.6%). At least one potential pathogen was reported from 70.1% of wound swab and 86.1% of tissue samples. Pathogen results differed between sampling methods in 58% of patients, with more pathogens and fewer contaminants reported from tissue specimens.The majority of pathogens were reported significantly more frequently in tissue than wound swab samples (P<0.01), with equal disagreement for S. aureus and Pseudomonas aeruginosa. Blinded clinicians more often recommended a change in antibiotic regimen based on tissue compared with wound swab results (increase of 8.9%, 95% CI 2.65% to 15.3%). Ulcer pain and bleeding occurred more often after tissue collection versus wound swabs (pain: 9.3%, 1.3%; bleeding: 6.8%, 1.5%, respectively).

CONCLUSION

Reports of tissue samples more frequently identified pathogens, and less frequently identified non-pathogens compared with wound swab samples. Blinded clinicians more often recommended changes in antibiotic therapy based on tissue compared with wound swab specimens. Further research is needed to determine the effect of the additional information provided by tissue samples.

TRIAL REGISTRATION NUMBER

ISRCTN52608451.

Effects of pH on the Antibiotic Resistance of Bacteria Recovered from Diabetic Foot Ulcer Fluid An In Vitro Study

BACKGROUND

This study investigated the resistance of bacteria isolated from diabetic foot ulcers (DFUs) to antibiotics frequently used in the management of the diabetic foot infections, at a range of pH values (pH 6.5, 7.5, and 8.5) known to exist in DFU wound fluid. This study aimed to determine whether changes (or atypical stasis) in wound fluid pH modulate the antibiotic resistance of DFU isolates, with potential implications in relation to the suppression/eradication of bacterial infections in DFUs.

METHODS

Thirty bacterial isolates were recovered from DFU wound fluid, including Staphylococcus spp, Staphylococcus aureus, Escherichia coli, Streptococcus spp, Pseudomonas spp, and Pseudomonas aeruginosa. The resistances of these isolates to a panel of antibiotics currently used in the treatment of infected or potentially infected DFUs, ie, ciprofloxacin, amoxicillin-clavulanate, doxycycline, and piperacillin-tazobactam, at the previously mentioned pH values were determined by a modification of the Kirby-Bauer assay.

RESULTS

The resistance of DFU isolates to clinically relevant antibiotics was significantly affected by the pH levels in DFU wound fluid.

CONCLUSIONS

These findings highlight the importance of a more comprehensive understanding of the conditions in DFUs to inform clinical decision making in the selection and application of antibiotics in treating these difficult-to-heal wounds. The scale of the differences in the efficacies of antibiotics at the different pH values examined is likely to be sufficient to suggest reconsideration of the antibiotics of choice in the treatment of DFU infection.

Complications during the treatment of diabetic foot osteomyelitis

AIM

To identify complications of medical treatment in patients with diabetic foot osteomyelitis (DFO).

METHODS

We reviewed 143 records of consecutive patients admitted with DFO, confirmed by bone histopathology or culture. Complications monitored included acute kidney injuries (AKI), development of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), gastrointestinal complications, and venous catheter related complications during a 12months follow-up period.

RESULTS

Forty-seven AKI episodes were reported during follow-up; half occurred during the first hospitalization with involvement of antimicrobial therapy in 14 events (29.8%). Patients with AKI were more likely to have recurrent ulcerations (69.2% vs. 45.2%, p=0.02), recurrent infections (38.5% vs. 17.3%, p=0.01), and recurrent hospitalizations (43.6% vs. 28.8%, p=0.02) during follow-up. Only 14 MRSA isolates were found in bone samples at baseline (9.8%). Resistant strains of MRSA and VRE were identified in twenty-one patients (14.7%) during follow-up. Patients re-hospitalized for infection were more likely to have resistant bacterial strains (52.6% vs. 25.8%, p=0.02).

CONCLUSIONS

In this study, the rates of VRE and MRSA in bone biopsies of patients with DFO were lower than in previous reports. Acute kidney injury occurred frequently in our patient population but might not be associated with antibiotic exposure.

Microbiology and Antimicrobial Therapy for Diabetic Foot Infections

In addition to being the prime factor associated with amputation, diabetic foot infections (DFIs) are associated with major morbidity, increasing mortality, and reduced quality of life. The choice of appropriate antibiotics is very important in order to reduce treatment failure, antimicrobial resistance, adverse events, and costs. We reviewed articles on microbiology and antimicrobial therapy and discuss antibiotic selection in Korean patients with DFIs. Similar to Western countries, Staphylococcus aureus is the most common pathogen, with Streptococcus, Enterococcus, Enterobacteriaceae and Pseudomonas also prevalent in Korea. It is recommended that antibiotics are not prescribed for clinically uninfected wounds and that empirical antibiotics be selected based on the clinical features, disease severity, and local antimicrobial resistance patterns. Narrow-spectrum oral antibiotics can be administered for mild infections and broad-spectrum parenteral antibiotics should be administered for some moderate and severe infections. In cases with risk factors for methicillin-resistant S. aureus or Pseudomonas, empirical antibiotics to cover each pathogen should be considered. The Health Insurance Review and Assessment Service standards should also be considered when choosing empirical antibiotics. In Korea, nationwide studies need to be conducted and DFI guidelines should be developed.

Inflammatory markers as risk factors for infection with multidrug-resistant microbes in diabetic foot subjects

BACKGROUND

Diabetic foot ulcers (DFUs), a dreadful microvascular complication of diabetes is responsible for substantial increase in morbidity and mortality. Infection, not a cause, but a consequence in DFUs that accounts for minor or major limb loss. The current study aimed to evaluate the microbial etiology of infected diabetic foot ulcers in northern tertiary care hospital, assessment of risk factors and role of inflammatory markers involved in colonization of multidrug-resistant organisms (MDROs) and their impact on the outcome.

METHODS

Pus aspirates and soft tissue samples from 65 patients with infected DFUs were collected and processed for aerobic culture analysis. Serum concentrations of IL-6 and TNF-α were determined by enzyme linked immuno-sorbent assay.

RESULTS

Aerobic gram-negative isolates were more commonly present (74.7%), followed by gram-positive aerobes (25.2%). Fifty-seven percent patients were positive for MDROs. IL-6 (pg/mL) was significantly lower in diabetic patients with MDROs infected foot ulcers than without (47.0±17.2 vs. 78.3±22.1 vs. p=<0.001) and TNF-α (pg/mL) was also significantly diminished in MDROs infected subjects than without (144.2±25.8 vs. 168.7±20.9, p<0.001) respectively.

CONCLUSIONS

In this study diabetic foot wounds harbored by MDROs were associated with longer duration of ulcer and increased ulcer size. Poor glycemic control was also a confounding factor in mounting MDROs infected ulcers. The declined levels WBCs and neutrophils as well as of cytokines IL-6 and TNF-alpha explains compromised immune responses of host in multi drug resistant infections.

Infrared skin thermometry: an underutilized cost-effective tool for routine wound care practice and patient high-risk diabetic foot self-monitoring

PURPOSE

To provide information about the use of infrared skin thermometry for routine wound care practice and patient high-risk diabetic foot self-monitoring.

TARGET AUDIENCE

This continuing education activity is intended for physicians and nurses with an interest in skin and wound care.

OBJECTIVES

After participating in this educational activity, the participant will be able to:1. Describe infrared thermometer use and the authors' study findings.2. Summarize studies that have evaluated the use of infrared thermometers for measuring skin temperature of the diabetic foot.

ABSTRACT

The aim of this article is to provide practitioners with an overview of infrared skin thermometry for everyday wound care practice. Thermometers have the potential for home use by patients with neuropathy to self-detect damage from repetitive trauma that will increase the risk of foot ulceration.

A post-planktonic era of in vitro infectious models: issues and changes addressed by a clinically relevant wound like media

Medical science is pitted against an ever-increasing rise in antibiotic tolerant microorganisms. Concurrently, during the past decade, biofilms have garnered much attention within research and clinical practice. Although the significance of clinical biofilms is becoming very apparent, current methods for diagnostics and direction of therapy plans in many hospitals do not reflect this knowledge; with many of the present tools proving to be inadequate for accurately mimicking the biofilm phenomenon. Based on current findings, we address some of the fundamental issues overlooked by clinical labs: the paradigm shifts that need to occur in assessing chronic wounds; better simulation of physiological conditions in vitro; and the importance of incorporating polymicrobial populations into biofilm models. In addition, this review considers using a biofilm relevant in vitro model for cultivating and determining the antibiotic tolerance and susceptibility of microorganisms associated with chronic wounds. This model presents itself as a highly rapid and functional tool that can be utilized by hospitals in an aim to improve bedside treatments.

Modern Orthopedic Inpatient Care of the Orthopedic Patient With Diabetic Foot Disease

In this article, we describe emergency and elective pathways within our orthopedic multidisciplinary inpatient care of patients with diabetic foot problems. We performed a retrospective cohort review of 19 complex patients requiring orthopedic surgical treatment of infected ulceration or Charcot feet or deformity at our institution. A total of 30 admissions (19 emergency, 11 elective) were included. The pathways were coordinated by a multidisciplinary team and comprised initial assessment and investigation and a series of key events, which consisted of emergency and elective surgery together with the introduction, and change of intravenous antibiotics when indicated. Patients had rigorous microbiological assessment, in the form of deep ulcer swabs, operative tissue specimens, joint aspirates, and blood cultures according to their clinical presentation as well as close clinical and biochemical surveillance, which expedited the prompt institution of key events. Outcomes were assessed using amputation rates and patient satisfaction. In the emergency group, there were 5.6 ± 3.0 (mean ± SD) key events per admission, including 4.2 ± 2.1 antibiotic changes. In the elective group, there were 4.8 ± 1.4 key events per inpatient episode, with 3.7 ± 1.3 antibiotic changes. Overall, there were 3 minor amputations, and no major amputations. The podiatric and surgical tissue specimens showed a wide array of Gram-positive, Gram-negative, aerobic and anaerobic isolates and 15% of blood cultures showed bacteremia. When 9 podiatric specimens were compared with 9 contemporaneous surgical samples, there was concordance in 2 out of 9 pairs. We have described the successful modern care of the orthopedic diabetic foot patient, which involves close clinical, microbiological, and biochemical surveillance by the multidisciplinary team directing patients through emergency and elective pathways. This has enabled successful surgical intervention involving debridement, pressure relief, and stabilization, with low rates of amputation.

Neuropathic Minimally Invasive Surgeries (NEMESIS):: Percutaneous Diabetic Foot Surgery and Reconstruction

Patients with peripheral neuropathy associated with ulceration are the nemesis of the orthopedic foot and ankle surgeon. Diabetic foot syndrome is the leading cause of peripheral neuropathy, and its prevalence continues to increase at an alarming rate. Poor wound healing, nonunion, infection, and risk of amputation contribute to the understandable caution toward this patient group. Significant metalwork is required to hold these technically challenging deformities. Neuropathic Minimally Invasive Surgeries is an addition to the toolbox of management of the diabetic foot. It may potentially reduce the risk associated with large wounds and bony correction in this patient group.

Sample procurement for cultures of infected wounds: a systematic review

OBJECTIVE

Identifying the responsible pathogen is required in order to select optimum antimicrobial therapy for infected wounds, but the best techniques to use remain the subject of debate. Our aim was to assess the evidence on the value of wound swabs compared with biopsies.

METHOD

We conducted a systematic literature review with the terms 'wound infection', 'wound swab', 'wound swab technique', 'wound biopsy', 'wound culture', 'wound swab comparison', 'Levine swab technique', 'microbiological technique', 'specimen handling', 'bacterial load', 'perioperative care', 'swab', and 'culture'. We examined yields in identifying relevant pathogens, summarised salient features of qualifying studies, and defined knowledge gaps and endpoints that future studies should address.

RESULTS

Studies have been inconsistent, lacking specificity regarding wound types, clinical features, and sampling methods. We found moderate quality evidence that punch biopsies provide qualitative and quantitative information about the bacterial load and tissue reaction with nearly 100% sensitivity, 90% specificity and 95% accuracy for predicting wound closure. Biopsies are relatively invasive, costly, require skilled operators, and potentially exacerbate infection. Needle aspiration samples a limited portion and may enter uninfected tissue and extend infection. Wound swabs are minimally invasive, easier to perform and widely employed in clinical practice, but techniques vary. In comparative studies, the Levine technique was superior to the Z-swab techniques, and biopsies were more sensitive for antibiotic-resistant wounds than Levine or Levine-like swabs, suggesting that swabs may be useful for initial wound monitoring, but biopsies are preferred when antibiotic resistance is suspected.

CONCLUSION

The Levine swab is superior to the Z-swab technique and may be useful for initial wound monitoring, but quantitative biopsies are preferred for evaluation of antibiotic-resistant wounds and to monitor the response to treatment. There is limited evidence on the role of wound swabs for detecting wound colonisation versus infection and the impact of culture-guided therapy on such clinical outcomes as eradication of infection and accelerated healing. Future studies should specify patient populations, wound types, sampling protocols, and outcomes based on culture yield and treatment results, using rigorous statistical methodology.

Deep tissue biopsy vs. superficial swab culture, including microbial loading determination, in the microbiological assessment of Skin and Soft Tissue Infections (SSTIs)

Thirty-two patients affected by SSTIs including DFIs were enrolled between 2013 and 2014. Superficial swab was obtained before and after cleansing with sterile saline, and after ultrasonic debridement; deep tissue biopsy was obtained from ulcer base. Samples were diluted with 1 mL of saline, serial 10-fold dilutions to 10^-6 were made and 50 μL of each dilution was plated onto appropriate media. Bacteria were identified by Vitek II system. Microbial load was expressed as CFU/mL. Statistical analysis was performed by χ2. Incidence of Gram positives was higher than Gram negatives (S. aureus and P. aeruginosa being the most frequent); concordance (same bacteria isolated before and after debridement) never exceeded 60%. Ultrasonic debridement significantly reduced bacterial load or even suppressed bacterial growth. While reliability of superficial swab is poor for microbiological diagnosis of SSTIs, swabbing after ultrasonic debridement and biopsy of the ulcer base may be equally reliable.

Infection in the Neuroischemic Foot

Infection in the neuroischemic foot can lead to cellulitis, which often progresses to necrosis as a result of septic vasculitis. Therefore, it is important to diagnose infection early. However, the signs and symptoms of infection are diminished in the neuroischemic foot. Microbiological investigation is essential. Severe infection needs intravenous antibiotic therapy and urgent assessment of the need for surgical drainage and debridement. Infected neuroischemic feet need vascular assessment and intervention where appropriate. It is important to maintain strict metabolic control and optimize cardiovascular function. Recent modern approaches based on multi-disciplinary clinics have resulted in improved results in the management of infection in the ischemic diabetic foot.

Pitfalls in diagnosing diabetic foot infections

Although the diagnosis of a diabetic foot infection is made based on clinical symptoms and signs, we also use blood laboratory, microbiological and radiological studies to make treatment decisions. All of these diagnostic studies have pitfalls that can lead to a delay in diagnosis. Such delays will likely lead to further tissue damage and to a higher chance of amputation. One of these pitfalls is that some clinicians rely on microbiological, rather than clinical data, to diagnose infection. Though subjective by nature, clinical signs predict outcome of foot infections accurately. Another pitfall is that microbiological data can be misleading. All wounds harbour microorganisms; therefore, a positive wound culture does not mean that a wound is infected. Furthermore, the outcome of cultures of wound swabs does not correlate well with culture results of tissue biopsies. Therapy guidance by wound swab will likely lead to overtreatment of non-pathogenic organisms. Genotyping might have a role in identifying previously unrecognized (combinations of) pathogens in diabetic foot infection, bacteria in sessile phenotype and non-culturable pathogens, e.g. in cases where antibiotics have already been administered. One more pitfall is that the diagnosis of osteomyelitis remains difficult. Although the result of percutaneous bone biopsy is the reference standard for osteomyelitis, some other diagnostic modalities can aid in the diagnosis. A combination of several of these diagnostic tests is probably a good strategy to achieve a higher diagnostic accuracy. Relying on a single test will likely lead to misidentification of patients with osteomyelitis with associated overtreatment and undertreatment.

A Comparison of Tissue versus Swab Culturing of Infected Diabetic Foot Wounds

Objective. To compare the efficacy of swabbing versus tissue biopsy for microbiological diagnosis of diabetic foot infection. Methods. This was a prospective trial. Fifty-six patients with diabetic foot infection were divided into the following 3 groups according to the PEDIS grading system: grade 2 (n = 10), grade 3 (n = 29), and grade 4 (n = 17). Two specimens were collected from each wound for microbial culturing after debridement, including a superficial swab and a deep tissue punch biopsy specimen. Results. Swab culturing identified all of the microorganisms isolated from the corresponding deep tissue specimens in 9/10 of grade 2 wounds (90.0%), and this proportion decreased to 12/29 (41.4%) and 7/17 (41.2%) for grades 3 and 4 wounds, respectively (p = 0.02). Moreover, the sensitivity for identifying Gram-negative bacteria, such as E. coli and Citrobacter, by swabbing was low (33.3%). In addition, some Gram-negative bacteria, such as Serratia and Ralstonia pickettii, were isolated from deep tissues but not from swabs. Conclusions. Swab culturing may be reliable for identification of pathogens in diabetic foot wounds classified as grade 2. However, it is advisable to culture deep tissue specimens for wounds of grade ≥3 because swab culturing is associated with a high risk of missing pathogens, especially Gram-negative bacteria.

Isolation and Antibiotic Susceptibility of the Microorganisms Isolated from Diabetic Foot Infections in Nemazee Hospital, Southern Iran

Background. Diabetic foot infections (DFIs) are a major public health issue and identification of the microorganisms causing such polymicrobial infections is useful to find out appropriate antibiotic therapy. Meanwhile, many reports have shown antibiotic resistance rising dramatically. In the present study, we sought to determine the prevalence of microorganisms detected on culture in complicated DFIs in hospitalized patients and their antibiotic sensitivity profiles. Methods. A cross-sectional study was conducted for a period of 24 months from 2012 to 2014 in Nemazee Hospital, Shiraz, Iran. The demographic and clinical features of the patients were obtained. Antimicrobial susceptibility testing to different agents was carried out using the disc diffusion method. Results. During this period, 122 aerobic microorganisms were isolated from DFIs. Among Gram-positive and Gram-negative bacteria, Staphylococcus spp. and E. coli were the most frequent organisms isolated, respectively. Of the isolates, 91% were multidrug while 78% of S. aureus isolates were methicillin resistant. 53% of Gram-negative bacteria were positive for extended-spectrum β-lactamase. Conclusion. Given the involvement of different microorganisms and emergence of multidrug resistant strains, clinicians are advised to consider culture before initiation of empirical therapy.

Indications and practical implementation of microbiologic diagnostics in patients with chronic wounds

Microbiology diagnostics are frequently performed in patients with chronic wounds. However, there is currently a lack of uniformity with respect to indications as well as the practical implementation of such workup. The fact that diagnostic results may be significantly affected by the sampling technique used as well as the preceding (wound) preparation underscores the need for uniform standards, which have been missing so far. In Germany, bacteriologic wound swabs are routinely performed, particularly with the intent to screen for multiresistant pathogens. For this indication, prior wound cleansing should be avoided, and sampling using the Essen Rotary technique provides a quick and easy-to-use option. If there is clinical suspicion of an infection, wound cleansing with sterile saline solution (0.9 %) and/or sterile cotton gauze should be carried out prior to obtaining bacteriologic swabs. While routine diagnostic biopsies are generally not required in chronic wound patients, they may be useful in case of clinically suspected wound infections, particularly in patients with deep ulcerations, diabetic foot syndrome, severe soft tissue infection, or fistula tissue. Moreover, biopsies are indispensable in the microbiology workup of specific pathogens such as mycobacteria, Leishmania, actinomycetes, Nocardia ssp. or molds.