Changing microbiological profile of pathogenic bacteria in diabetic foot infections: time for a rethink on which empirical therapy to choose?

Analysis of Distribution and Drug Susceptibility Test Results of Pathogenic Bacteria in Diabetic Foot Ulcers

INTRODUCTION

This study aimed to determine the pathogen distribution and drug susceptibility of diabetic foot wound secretions in a tertiary hospital in a coastal area of southeastern China to guide clinical antibiotic selection.

METHODS

A retrospective analysis was conducted on 212 patients with diabetic foot hospitalized at Xiamen Third Hospital from 2018 to 2023, and foot wound secretions were collected for microbial culture and drug susceptibility testing.

RESULTS

Among 212 cases of patients with diabetic foot wound secretions, 163 cases (76.9%) were cultured with pathogenic bacteria, and a total of 207 strains of pathogenic bacteria were cultured, including 75 strains (36.23%) of Gram-positive (G+) bacteria, 118 strains of Gram-negative (G-) bacteria (57.00%), 14 strains of fungi (6.76%), 120 cases of single microorganism infection (73.62%), 43 cases of mixed infection (26.38%), and 15 strains of multidrug-resistant bacteria (7.25%). The top three pathogenic bacteria were Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. G+ bacteria were dominated by S. aureus. Drug susceptibility results showed that G+ bacteria were highly susceptible to vancomycin, linezolid, tigecycline, quinupristin/dalfopristin, rifampicin, and furotoxin, and somewhat resistant to penicillin, erythromycin, clindamycin, and cefoxitin. Among G- bacterial infections, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Proteus were the major species. Drug susceptibility testing indicated that carbapenems such as imipenem and ertapenem were the most effective antibacterial drugs against G- strains, followed by amikacin, piperacillin, and tazabactams to which these bacteria were also relatively sensitive, while resistance to penicillins and first-generation cephalosporins increased significantly. We isolated one strain of pathogenic bacteria from a Wagner grade 1 ulcer, which was G+ bacteria. In Wagner grade 2 ulcers, the distribution of pathogenic bacteria was mainly G+ bacteria. In Wagner grade 3 and 4 ulcers, the distribution of pathogenic bacteria was mainly G- bacteria, and the increased rate of mixed infection was mainly due to mixed infection of G+ and G-. Two strains of pathogenic bacteria were isolated at Wagner grade 5, which were mixed infections of G+ and G-.

CONCLUSIONS

Pathogenic bacteria in diabetic foot wounds are predominantly G- bacteria, followed by G+ bacteria. As the Wagner ulcer grade increases, the distribution of pathogenic bacteria changes from G+ bacteria to G- bacteria, and the mixed infection rate increases. G+ bacteria are highly susceptible to vancomycin, linezolid, tigecycline, quinupristin/dalfopristin, rifampicin, and furotoxin, and somewhat resistant to penicillin, erythromycin, clindamycin, and cefoxitin. G- bacteria are more sensitive to the antimicrobial drugs ertapenem, imipenem, amikacin, piperacillin tazobactam, and have high resistance to penicillin and first-generation cephalosporins.

Microbiological profile of diabetic foot infections in China and worldwide: a 20-year systematic review

Introduction

Pathogens causing diabetic foot infections (DFIs) vary by region globally; however, knowledge of the causative organism is essential for effective empirical treatment. We aimed to determine the incidence and antibiotic susceptibility of DFI pathogens worldwide, focusing on Asia and China.

Methods

Through a comprehensive literature search, we identified published studies on organisms isolated from DFI wounds from January 2000 to December 2020.

Results

Based on our inclusion criteria, we analyzed 245 studies that cumulatively reported 38,744 patients and 41,427 isolated microorganisms. DFI pathogens varied according to time and region. Over time, the incidence of Gram-positive and Gram-negative aerobic bacteria have decreased and increased, respectively. America and Asia have the highest (62.74%) and lowest (44.82%) incidence of Gram-negative bacteria, respectively. Africa has the highest incidence (26.90%) of methicillin-resistant Staphylococcus aureus. Asia has the highest incidence (49.36%) of Gram-negative aerobic bacteria with species infection rates as follows: Escherichia coli, 10.77%; Enterobacter spp., 3.95%; and Pseudomonas aeruginosa, 11.08%, with higher local rates in China and Southeast Asia. Linezolid, vancomycin, and teicoplanin were the most active agents against Gram-positive aerobes, while imipenem and cefoperazone-sulbactam were the most active agents against Gram-negative aerobes.

Discussion

This systematic review showed that over 20 years, the pathogens causing DFIs varied considerably over time and region. This data may inform local clinical guidelines on empirical antibiotic therapy for DFI in China and globally. Regular large-scale epidemiological studies are necessary to identify trends in DFI pathogenic bacteria.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023447645.

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.

Staphylococcus aureus Is the Predominant Pathogen in Hospitalised Patients with Diabetes-Related Foot Infections: An Australian Perspective

Diabetes prevalence continues to increase worldwide, which has led to a rising incidence of diabetes-related foot infections (DFIs). There is significant local variation in the microbiology of DFIs, and Pseudomonas spp. is suggested to be more prevalent in subtropical climates. The aim of this study was to investigate the local microbiological findings in patients admitted to the hospital with DFIs. This retrospective study analysed data from all adult patients diagnosed with diabetes and admitted to the hospital for the treatment of a DFI between 1 January 2021 and 31 December 2022. Both superficial wound swabs and tissue cultures were included. The Infectious Diseases Society of America classification system was used to categorise the severity of the DFI. Patient characteristics and demographics were analysed using descriptive statistics. One hundred fifty-one episodes of care were included. Most of the DFIs were classified as moderate infections 101/151 (67%). The most commonly isolated microorganism was Staphylococcus aureus (33%) followed by normal skin flora (11%) and β-haemolytic streptococci (7%). P. aeruginosa was isolated more commonly in those with chronic DFIs (10%) compared to those with acute DFIs (2%). Despite the frequent identification of S. aureus, 83% of patients received an antipseudomonal antibiotic. The introduction of multidisciplinary DFI rounds should be considered.

Glucose-Responsive Self-Healing Bilayer Drug Microneedles Promote Diabetic Wound Healing Via a Trojan-Horse Strategy

Chronic nonhealing wounds are serious complications of diabetes with a high morbidity, and they can lead to disability or death. Conventional drug therapy is ineffective for diabetic wound healing because of the complex environment of diabetic wounds and the depth of drug penetration. Here, we developed a self-healing, dual-layer, drug-carrying microneedle (SDDMN) for diabetic wound healing. This SDDMN can realize transdermal drug delivery and broad-spectrum sterilization without drug resistance and meets the multiple needs of the diabetic wound healing process. Quaternary ammonium chitosan cografted with dihydrocaffeic acid (Da) and l-arginine and oxidized hyaluronic acid-dopamine are the main parts of the self-healing hydrogel patch. Methacrylated poly(vinyl alcohol) (methacrylated PVA) and phenylboronic acid (PBA) were used as the main part of the MN, and gallium porphyrin modified with 3-amino-1,2 propanediol (POGa) and insulin were encapsulated at its tip. Under hyperglycaemic conditions, the PBA moiety in the MN reversibly formed a glucose-boronic acid complex that promoted the rapid release of POGa and insulin. POGa is disguised as hemoglobin through a Trojan-horse strategy, which is then taken up by bacteria, allowing it to target bacteria and infected lesions. Based on the synergistic properties of these components, SDDMN-POGa patches exhibited an excellent biocompatibility, slow drug release, and antimicrobial properties. Thus, these patches provide a potential therapeutic approach for the treatment of diabetic wounds.

The Influence of Honey and Hydrogel Products Therapy on Healing Time in Diabetic Foot

BACKGROUND

Diabetic foot ulcer is a serious and common complication of diabetes that often leads to significant morbidity and even amputation if not properly treated. Current treatment options, such as wound dressing, have limitations in promoting efficient healing. There is a need for effective interventions that can expedite the healing process and enhance the time required for complete healing.

METHODOLOGY

This prospective single-blinded randomized control trial studied diabetic mellitus type 2 patients with ulcer in their second-degree feet from February 2019 to February 2023 in the Diabetic Foot Center, King Fahad Specialist Hospital Al Qassim-KSA.

RESULTS

This study involved 120 patients with a mean age of 59.64 ± 10.21. And 63% to 52.5% of them were males and 57% to 47.5% were females. The mean healing time was about 12.76 ± 4.08 days. Cases were divided into 4 equal groups with altered treatment procedures: honey alone, hydrogel alone, honey, and hydrogel combination alternately (3 intervention groups), and fucidin ointment or cream alone (1 control group), with 30 participants in each group. We revealed that the mean healing times for honey alone, hydrogel alone, and honey and hydrogel alternately were 12.20, 13.97, and 10.83 days, respectively. While it was 14.03 days in the control Fucidin ointment or cream [significantly P < .05 (P = .004)].

CONCLUSION

From the findings of the present study, we noticed that faster healing time among diabetic foot cases could be accomplished by treatment with a combination of honey and hydrogel alternately. Therefore, this therapy is effective in reducing the risk of diabetic foot ulcers.

Prevalence of S. aureus and/or MRSA in hospitalized patients with diabetic foot and establishment of LAMP methods for rapid detection of the SCCmec gene

BACKGROUND

Patients with diabetic feet are prone to be infected due to the impaired immune system. However, the prognostic outcome of different microbial infections remains controversial. Identification and rapid screening of the pathogenic microorganisms that pose the greatest threat to the prognosis of patients with diabetic foot infections (DFIs) is critical.

METHODS

Clinical data were statistically analyzed, which were obtained from 522 patients with DFIs, including pathogenic bacterial culture results and treatment outcomes at the last return visit. In addition, a loop-mediated isothermal amplification (LAMP) detection method was developed to identify the prevalent subtype of methicillin-resistant Staphylococcus aureus (MRSA) in DFIs patients. This study was approved by the Ethics Committee of Nanfang Hospital (NFEC-202012-K6) and registered on ClinicalTrials.gov (NCT04916457) on June 1, 2021.

RESULTS

We found that the proportion of patients with infections of Staphylococcus aureus (S. aureus) and MRSA was 27.7% (145/522) and 33.7% (49/145), respectively. Additionally, the incidence of osteomyelitis was 46.9% (23/49) and amputation/disability was 40.8% (20/49) in patients with MRSA infection, which were significantly higher compared to patients with other types of bacterial infections such as methicillin-susceptible Staphylococcus aureus (MSSA). Notably, we demonstrated that the main prevalent subtype of MRSA in DFIs patients in our hospital was Staphylococcal chromosomal cassettes mec (SCCmec) type II. In addition, it only takes 1.5 h to complete the entire experimental procedure in this LAMP assay, providing high sensitivity (100%) and specificity (77.8%) in hospitalized patients with DFIs.

CONCLUSIONS

We demonstrated there is a very high rate of MRSA isolation in patients with DFIs and revealed that patients infected with MRSA are at a higher risk of developing osteomyelitis, and amputation or disability. Importantly, we have developed a method for quickly screening newly admitted patients for MRSA.

Parenteral Vancomycin in the Treatment of MRSA-Associated Diabetic Foot Infections: An Unnecessary Risk

Diabetic foot infections (DFIs) are a common and costly complication of diabetes. Soft tissue and bone infections in DFIs frequently lead to amputation and/or sepsis which can be costly for both the patient and the healthcare system. Staphylococcus aureus is the most commonly identified causative agent in DFIs, and people with diabetes may have an increased risk of infection with methicillin-resistant Staphylococcus aureus (MRSA). In addition to increased susceptibility to severe infection, MRSA in DFIs is associated with high rates of treatment failure, morbidity, and hospitalization costs meaning appropriate treatment is a high priority. While hospitalized patients are usually treated with intravenous (IV) vancomycin, this can be costly in terms of inpatient stays, staffing costs, and adverse events. For example, vancomycin-associated acute kidney injury not only delays hospital discharge and increases costs but is also a particular concern for patients with diabetes who already have an increased risk of kidney problems. Vancomycin-resistant strains of S. aureus have also been identified, which means that alternative treatment options may need to be explored. Treatment alternatives to IV vancomycin, including oral antibiotics, have been shown to provide similar efficacy, with reduced costs, outpatient or home-based administration, and with fewer serious adverse effects. Although infectious disease specialists often use IV vancomycin alone, or in combination, as a first-line therapeutic option, they are increasingly seeing the value of outpatient or at-home oral antibiotics as an alternative. This manuscript reviews the evidence for true costs of vancomycin therapy for MRSA-associated DFIs and examines the alternatives.

Metagenomic analysis reveals antibiotic resistance profiles in tissue samples from patients with diabetic foot infections

OBJECTIVES

Treating patients with diabetic foot infection (DFI) is challenging because of high rates of antibiotic resistance. Therefore, to administer a suitable antibiotic treatment, it is necessary to know the antibiotic resistance patterns in DFIs.

METHODS

To explore this question, we selected metagenomic data of 36 tissue samples from patients with DFI in the National Center for Biotechnology Information Sequence Read Archive database.

RESULTS

A total of 229 antibiotic-resistant gene (ARG) subtypes belonging to 20 ARG types were detected. The antibiotic resistome of 229 different genes in the tissue samples of patients with DFI comprised 24 core and 205 accessory resistance genes. Among the core antibiotic resistome, multidrug, tetracycline, macrolide-lincosamide-streptogramin, and beta-lactam resistance genes were the dominant categories. Procrustes analysis indicated that both the microbial community composition and mobile genetic elements (MGEs) were determinants of the ARGs. In the network analysis, 29 species were speculated to be potential hosts of 28 ARGs based on the co-occurrence results. Plasmids and transposons were the most common elements that co-occurred with ARGs.

CONCLUSIONS

Our study provided detailed information about antibiotic resistance patterns in DFI, which has practical implications for suggesting a more specific antibiotic choice.

Diabetic foot ulcer-a systematic review on relevant microbial etiology and antibiotic resistance in Asian countries

BACKGROUND AND AIMS

Diabetic foot ulcer (DFU) is one of the most common but uncontrolled health issues of diabetic patients that needs more therapeutic considerations. This systematic review aims to study the current status of the etiological agents responsible for DFU, their frequency in some of the most occurring Asian countries, and their antibiotic resistance pattern based on available studies.

METHODS

Here, the literature survey was conducted on all the DFU studies with the records of etiological agents and conventional therapeutic treatment published until March 2021 using Medical Literature Analysis and Retrieval System Online (MEDLINE) and Web of Science Core Collection (WoSCC) database.

RESULTS

Overall, in our study, a total of 73 studies representing 12 Asian countries worldwide have been included. We found that the highest number of studies were reported from India (45%) followed by Pakistan (11%), China, Iran and others. 71% of recent studies reported DFU being attributed to poly-microbial infections while the dominant position was significantly secured by Gram- negative bacteria (77%, p = 0.34). Staphylococcus aureus was found to be the most prevalent isolate followed by Pseudomonas and then Escherichia coli (mean value - 22%, 17%, and 15% respectively). Antibiotic sensitivity pattern was determined based on availability in terms of median resistance (MR) and interquartile range (IQR) which showed the growing resistance developed by both Gram-positive and Gram-negative isolates. Gram positive pathogens were still reported as susceptible to vancomycin (MR 0%, IQR 0-22.8%), linezolid (MR 0%, IQR 0-15.53%) and imipenem (MR 11%, IQR 0-23.53%). Carbapenem genera, colistin, and amikacin were the most effective drugs against Gram-negative pathogens.

CONCLUSION

The findings of this study highly recommend searching for alternative and complementary therapeutic regimens instead of prescribing conventional drugs blindly without investigating the progression of the stages of the ulcer, which may help reduce the medical and economic burden of this disease.

Relative Abundance and Detection of Pseudomonas aeruginosa from Chronic Wound Infections Globally

Pseudomonas aeruginosa is a difficult-to-treat pathogen that is frequently involved with chronic wound infections. Here, we conducted a literature search of world-wide studies published between 2005 and 2022 that described the microbiological profiles of chronic wound infections. For each continent, a hierarchy of pathogens was created to define the organisms that were most frequently isolated in each region. Except for South America, P. aeruginosa was the second most common organism in each major continent, with Staphylococcus aureus being the most abundant pathogen overall. When individual countries were evaluated, P. aeruginosa was the most frequently isolated organism in several Southeast Asia nations including India and Malaysia. P. aeruginosa was less commonly isolated from diabetic foot infections in North America, Europe, and Africa in comparison to other types of chronic wound infections. Additionally, the Levine wound swab technique may be a quick and painless way to isolate P. aeruginosa from wound infections, but the isolation of P. aeruginosa does not seem to be an informative predictor of the patient's clinical course. A multivariate risk assessment that accounts for the regional frequency of P. aeruginosa isolation may be an appropriate way to guide empiric management of chronic wound infections.

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.

Understanding the multifaceted etiopathogenesis of foot complications in individuals with diabetes

Diabetes mellitus, a chronic disease of metabolism, is characterized by a disordered production or cellular utilization of insulin. Diabetic foot disease, which comprises the spectrum of infection, ulceration, and gangrene, is one of the most severe complications of diabetes and is the most common cause of hospitalization in diabetic patients. The aim of this study is to provide an evidence-based overview of diabetic foot complications. Due to neuropathy, diabetic foot infections can occur in the form of ulcers and minor skin lesions. In patients with diabetic foot ulcers, ischemia and infection are the main causes of non-healing ulcers and amputations. Hyperglycemia compromises the immune system of individuals with diabetes, leading to persistent inflammation and delayed wound healing. In addition, the treatment of diabetic foot infections is challenging due to difficulty in accurate identification of pathogenic microorganisms and the widespread issue of antimicrobial resistance. As a further complicating factor, the warning signs and symptoms of diabetic foot problems can easily be overlooked. Issues associated with diabetic foot complications include peripheral arterial disease and osteomyelitis; accordingly, the risk of these complications in people with diabetes should be assessed annually. Although antimicrobial agents represent the mainstay of treatment for diabetic foot infections, if peripheral arterial disease is present, revascularization should be considered to prevent limb amputation. A multidisciplinary approach to the prevention, diagnosis, and treatment of diabetic patients, including those with foot ulcers, is of the utmost importance to reduce the cost of treatment and avoid major adverse consequences such as amputation.

Bacterial Diversity, Antibiotic Resistance, and the Risk of Lower Limb Amputation in Younger and Older Individuals With Diabetic Foot Infection

INTRODUCTION

A diabetic foot infection (DFI) contributes to high mortality and morbidity in diabetics due to its often rapid progressive and intricately treatable infection. DFIs are usually a polymicrobial infection and characterizing the entire bacterial load is still challenging. Prompt and effective treatment of DFI is nevertheless mandatory to safe limbs and lives. It is therefore crucial to know the local pathogen spectrum and its antibiotic susceptibility.

METHODS AND MATERIAL

For a 12-month period, we investigated 353 individuals with infected diabetic foot ulcer, their bacterial diversity, and antimicrobial susceptibility at fist-time visit in a Diabetic Foot Care Center in southern Germany.

RESULTS

Cultures yielded 888 species, most of them gram-positive cocci (primary Staphylococcus aureus). The gram-negative sector was mainly formed by Pseudomonas aeruginosa and Enterobacteriacae. Because the prevalence of multiresistant species was surprisingly low (0.9% of isolated strains), we suggest penicillins with β-lactamase inhibitor in case of gram-positive-dominated infection or piperacillin/tazobactam or rather carbapenems with equal efficacy when gram-negative species are involved.

Pseudomonas aeruginosa: Infections, Animal Modeling, and Therapeutics

Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen which causes many severe acute and chronic infections with high morbidity, and mortality rates as high as 40%. What makes P. aeruginosa a particularly challenging pathogen is its high intrinsic and acquired resistance to many of the available antibiotics. In this review, we review the important acute and chronic infections caused by this pathogen. We next discuss various animal models which have been developed to evaluate P. aeruginosa pathogenesis and assess therapeutics against this pathogen. Next, we review current treatments (antibiotics and vaccines) and provide an overview of their efficacies and their limitations. Finally, we highlight exciting literature on novel antibiotic-free strategies to control P. aeruginosa infections.

Diabetic Foot Infection Characteristics and Antibiotics Susceptibility Patterns in a Regional Hospital in Libya

Introduction Diabetes is a major global health problem, among the top causes of death worldwide. Diabetic foot infection (DFI) is associated with an increased risk of amputation by 155 times and a mortality rate of 57% at 5 years. This study aims to characterize DFI epidemiology in a local hospital and analyze local microbiological patterns and antibiotic susceptibility testing.

Patients and Methods This is a retrospective review of Al Jala hospital Benghazi/Libya medical records. Eligible patients were included, if they had DFI with confirmed tissue/pus samples collections was submitted to the hospital laboratory for microbiology and Antibiotics susceptibility analysis.

Results Out of 126 patients, 77 (61.1%) were men, and 49 (38.9%) were women. The mean age was 55.4 years. Incision drainage with debridement was the most common surgical procedure (77.1%). 38.88% of growth was polymicrobial. Gram-negative rods were isolated in 70.9%, and gram-positive cocci in 27.4%. The most commonly isolated bacteria were Pseudomonas aeruginosa (15.9%) and Proteus sps. (14.2%), Staphylococcus aureus (11.3%), and Escherichia coli (10.2%). Methicillin-resistant Staphylococcus aureus (MRSA) constitutes 30% of isolated S. aureus. The most common effective antibiotic for P. aeruginosa was imipenem (90%), for S. aureus was linezolid (100%), and for MRSA was linezolid, vancomycin (100%), and ciprofloxacin 88.8%. Sixty-four percent of total bacterial isolates were MDROs (gram-positive isolates 65.3%, gram-negative isolates 63.6%).

Conclusions The emergence of antibiotic-resistant bacteria is a global health concern. This study attempts to evaluate the local microbiology and antimicrobial susceptibility to tailor the treatment choice for better patient outcomes.

An all-in-one CO gas therapy-based hydrogel dressing with sustained insulin release, anti-oxidative stress, antibacterial, and anti-inflammatory capabilities for infected diabetic wounds

To effectively treat diabetic wounds, the development of versatile medical dressings that can long-term regulate blood glucose and highly effective anti-oxidative stress, antibacterial and anti-inflammatory are critical. Here, an all-in-one CO gas-therapy-based versatile hydrogel dressing (ICOQF) was developed via the dynamic Schiff base reaction between the amino groups on quaternized chitosan (QCS) and the aldehyde groups on benzaldehyde-terminated F108 (F108-CHO) micelles. CORM-401 (an oxidant-sensitive CO-releasing molecules) was encapsulated in the hydrophobic core of F108-CHO micelles and insulin was loaded in the three-dimensional network structure of ICOQF. The dynamic Schiff base bonds not only endowed ICOQF with good tissue adhesion, injectability and self-healing, but also gave it sustained and controllable insulin release ability. In addition, ICOQF could quickly generate CO in inflamed wound tissue by consuming reactive oxygen species. The generated CO could effectively anti-oxidative stress by activating the expression of heme oxygenase; antibacterial by inducing the rupture of bacterial cell membranes and mitochondrial dysfunction and inhibiting the synthesis of adenosine triphosphate; and anti-inflammatory by inhibiting the proliferation of activated macrophages and promoting the polarization of the M1 phenotype to the M2 phenotype. Due to these outstanding properties, ICOQF significantly promoted the healing of STZ-induced MRSA-infected diabetic wounds accompanied by good biocompatibility. This study clearly shows that ICOQF is a versatile hydrogel dressing with great application potential for the management of diabetic wounds. STATEMENT OF SIGNIFICANCE: The development of some versatile hydrogel dressings that can not only provide a prolonged and controlled insulin release property but also utilize a non-antibiotic treatment modality for highly effective antibacterial, anti-inflammatory, and anti-oxidative stress effects is vital for the successful treatment of diabetic wounds. Herein, we developed an all-in-one CO gas-therapy-based versatile hydrogel dressing (ICOQF) with sustained and controllable insulin release abilities. Moreover, ICOQF could not only quickly release CO in the inflamed wound tissue by consumption of reactive oxygen species but also utilize the generated CO to highly effectively anti-oxidative stress, antibacterial, and anti-inflammatory. ICOQF therapy substantially promoted the healing of STZ-induced MRSA-infected diabetic wounds. Overall, this work provides a multifunctional hydrogel dressing for the management of diabetic wounds.

Microbiological, Clinical and Radiological Aspects of Diabetic Foot Ulcers Infected with Methicillin-Resistant and -Sensitive Staphylococcus aureus

Diabetic foot ulcer (DFU) is one of the most common chronic complications of diabetes. This study aimed to assess the factors with an impact on the infection of diabetic foot ulcers by methicillin-resistant S. aureus and to evaluate the influence of methicillin resistance on the frequency of osteitis (based on classic X-ray images). A total of 863 patients suffering from DFU were analyzed during the study period. Out of 201 isolated S. aureus cases, 31 (15.4%) were methicillin-resistant (MRSA). MRSA infections were associated with a higher incidence of osteitis compared to MSSA infections (p << 0.0001), both the occurrence of smaller (<50%)) and greater (>50%) inflammatory bone changes (p << 0.0001). Furthermore, MRSA occurred significantly more frequently in men than in women (p < 0.01) and more often among patients with type 2 diabetes than among patients with type 1 diabetes (p < 0.05). MRSA were isolated statistically less often in overweight patients than in patients with normal BMI (p < 0.05). DFUs infected with MRSA were significantly more frequently associated with the presence of Pseudomonas sp. and other non-fermenting bacilli than those infected with MSSA (p < 0.05). To conclude, osteitis incidence is related to MRSA infection in patients with diabetic foot ulcers; thus, patients infected by S. aureus should be closely monitored in the course of using antibiotics and treated with narrow-spectrum antibiotics.

Diabetic foot ulcer in Southern Jordan: A cross-sectional Study of Clinical and Microbiological Aspects

Background

Materials and methods

Results

Conclusion

•

Diabetic foot ulcer is a common complication of diabetes.

•

This study is first of its kind in southern Jordan that combined clinical and microbiological aspects of diabetic foot ulcer.

•

The most frequent bacterial isolates from diabetic foot ulcers are gram negative bacteria.

•

Inappropriate previous use of antibiotics is the main determinant of multi-drug resistant isolates.

•

High rates of multi-drug resistant isolates in this study reflect the loose implementation of antibiotics dispensing regulations in Jordan.

Diabetic Foot Ulcer Infections and Pseudomonas aeruginosa Biofilm Production During the COVID-19 Pandemic

During the different waves of the coronavirus (COVID-19) pandemic, there has been an increased incidence of diabetes mellitus and diabetic foot infections. Among gram-negative bacteria, Pseudomonas aeruginosa is the predominant causative agent for diabetic foot ulcer infections in low-resource countries. P. aeruginosa possesses a variety of virulence factors, including biofilm formation. Biofilm formation is an important benchmark characteristic in the pathophysiology of diabetic foot ulceration. The main objective of the current study was to identify the most commonly isolated organisms and their antibiotic susceptibility patterns in diabetic foot patients during the COVID-19 pandemic. We also determined the genes associated with bacterial persistence and biofilm formation in the predominantly isolated organism. Accordingly, 100 wound swab samples were collected from diabetic foot patients from different hospitals in Alexandria, Egypt. Through phenotypic detection of biofilm formation, 93% (40) of the 43 P. aeruginosa isolates examined were categorized as biofilm producers. Molecular detection of the biofilm-encoding genes among the 43 P. aeruginosa isolates was as follows: algD (100%), pelF (88%) and pslD (49.7%), and this highlights a need for biofilm formation inhibitors to prevent the persistence of bacterial pathogens, and thus achieve better clinical outcomes in diabetic foot ulcer infections.

Clinical and microbiological profile of bacterial pathogens from patients with diabetic foot infections at a teaching hospital in the northeast China

Background: Diabetic foot ulcer infection (DFI) is a frequent complication of diabetes.

Objective: The aim is to determine the clinical and microbiological profiles and the antibiotic resistance phenotype, analyze the DFIs risk factors.

Methods: The present study is a retrospective, single-center study conducted at a teaching hospital in the northeast China. 242 cases of patients with diabetic foot disease Wagner grade 0–5 over 2 years were screened and the recovered data consisted of the clinical features, risk factors, etiology and drug resistant profiles.

Results: The total percentage of Gram-negative rods (GNRs) and Gram-positive cocci (GPCs) was 138 (54.92%) and 113 (45.02%). The most common isolates were Pseudomonas aeruginosa and Staphylococcus aureus, accounting for 22.37% and 19.74%, respectively. Logistic regression analysis showed that the duration of ulcer, duration of antibiotic use, Wagner classification and osteomyelitis were risk factors for multi-drug resistant (MDR) bacteria infection ( p<0.05).

Conclusion: The predominate pathogens of patients with DFI were GNRs, followed by GPCs in the region. They exhibited the different antibiotic resistance phenotype. The data provided advice on selection of highly sensitive antibiotics in the management of DFIs.

Microbial Infection and Antibiotic Susceptibility of Diabetic Foot Ulcer in China: Literature Review

OBJECTIVE

To investigate the microbial spectrum isolated from foot ulcers among diabetic patients in China, which was conducted to help clinicians choose optimal antibiotics empirically.

METHOD

The PubMed, MEDLINE, Web of Science, China Biology Medicine (CBM), China National Knowledge Infrastructure (CNKI), WanFang, and VIP databases were searched for studies published between 2015 to 2019, that report primary data on diabetic foot infection (DFI) and antibiotic susceptibility in China.

RESULT

A total of 63 articles about DFI and antibiotic susceptibility tests among diabetic patients in China were included. There were 11,483 patients with an average age of 60.2 ± 10.1 years and a mean course of 10.6 ± 5.0 years between 2010 and 2019, covering most geographical regions of China. The prevalence of Gram-positive (GP) bacteria (43.4%) was lower than that of Gram-negative (GN) (52.4%). The most prevalent pathogens isolated were Staphylococcus aureus (17.7%), Escherichia coli (10.9%), Pseudomonas aeruginosa (10.5%), Klebsiella pneumoniae (6.2%), Staphylococcus epidermidis (5.3%), Enterococcus faecalis (4.9%), and fungus (3.7%). The prevalence of polymicrobial infection was 22.8%. GP bacteria were sensitive to linezolid, vancomycin, and teicoplanin. More than 50% of GN bacteria were resistant to third-generation cephalosporins, while the resistance rates of piperacillin/tazobactam, amikacin, meropenem, and imipenem were relatively low. Among the 6017 strains of the isolated organisms, 20% had multi-drug resistance (MDR). Staphylococcus aureus (30.4%) was the most predominant MDR bacteria, followed by extended-spectrum β-lactamase (ESBL) (19.1%).

CONCLUSION

The microbial infection of foot ulcers among diabetic patients in China is diverse. The microbial spectrum is different in different geographic regions and Staphylococcus aureus is the predominant bacteria. Polymicrobial and MDR bacterial infections on the foot ulcers are common. This study could be valuable in guiding the empirical use of antibiotics for diabetic foot infections.

Clinical Uses of NPWT with Irrigation of Normal Saline in Diabetic Foot Ulcer: Outcome Assessed by DEPA Score

Introduction

Diabetic foot ulcer (DFU) is a common complication of uncontrolled diabetes. Negative pressure wound therapy (NPWT) with irrigation of normal saline is one of the methods for wound care and dressing techniques in DFU. Wound assessment is another aspect of DFU management for deciding whether the wound is prepared or not for coverage. The present study uses DEPA score as a wound assessment tool in DFU.

Materials and Methods

This case series include 11 patients with DFU who were treated using NPWT with simultaneous irrigation of normal saline.

Results

All 11 patients were male and age more than 60. Most patients have duration of diabetes for less than 10 years. Staphylococcus aureus (n = 5, 45.4%) was most common bacterial flora. Most patients in series presented with DEPA score more than 7 and after application of NPWT instillation therapy significant improvement seen with score in most of the patient with DEPA score below 6. Mean time for NPWT (irrigation) application was 15 days. Mean time of wound preparation was 18.7 days. Final surgical procedures executed in all patients, split skin grafting performed in 7 patients. 4 patients had wound coverage by reverse sural flap (2), medial plantar flap (1) and local flap coverage (1).

Conclusion

NPWT with normal saline irrigation is an effective method of wound preparation in DFU. DEPA score is an important tool for assessment of wound preparation which gives exact information for timing of wound coverage once diabetic foot wound is prepared.

The microbiology of diabetic foot infections: a meta-analysis

Background

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

Methods

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

Results

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

Conclusion

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

Supplementary Information

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

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

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

Macrophage Related Chronic Inflammation in Non-Healing Wounds

Persistent hyper-inflammation is a distinguishing pathophysiological characteristic of chronic wounds, and macrophage malfunction is considered as a major contributor thereof. In this review, we describe the origin and heterogeneity of macrophages during wound healing, and compare macrophage function in healing and non-healing wounds. We consider extrinsic and intrinsic factors driving wound macrophage dysregulation, and review systemic and topical therapeutic approaches for the restoration of macrophage response. Multidimensional analysis is highlighted through the integration of various high-throughput technologies, used to assess the diversity and activation states as well as cellular communication of macrophages in healing and non-healing wound. This research fills the gaps in current literature and provides the promising therapeutic interventions for chronic wounds.

Analysis of the microbiota in the diabetic foot ulcers: Is research standardization required?

Background: Complications of infected wounds in patients with diabetic foot ulcer (DFU) are one of the greatest challenges in modern medicine. Analysis of the microbiological profile of infected ulcers may significantly improve treatment results. The aim of the study was to determine the profile of pathogens isolated in patients with DFU and to compare the results of other centers. Materials and Methods: A retrospective study was carried out on 137 patients with DFU hospitalized at the Department of Diabetology and Internal Diseases, Medical University of Warsaw in 2011-2014. The analysis included the results of 200 microbiological cultures tested for fungi, aerobic and anaerobic bacteria. Statistical analysis was used to test differences in HbA1c values in relation to the strain of the most commonly cultured bacteria and the relationship between glycemic control and most frequently isolated pathogens. Results: Seventy-nine bacterial species were isolated in 183 positive cultures. Gram-negative bacteria predominated with the highest percentage of representatives of Enterobacterales. The most often isolated bacteria were Serratia marcescens, Pseudomonas aeruginosa, Proteus mirabilis and methicillin-susceptible Staphylococcus aureus. The Kruskal-Wallis test revealed that HbA1c concentrations were different in groups infected with different strains of bacteria (p = 0.0087). Isolation of Escherichia coli and Morganella morganii was more often associated with poor control of diabetes. Conclusions: The study revealed statistically significant differences in the frequency of microorganisms isolated from the wounds of patients with DFU. The discrepancies in the results of other studies published in this field indicate the need for standardization of the research design.

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.

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

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

Spectral and Antibiotic Susceptibility of Pathogens Isolated from Saudi Patients with Diabetic Foot Infections

Diabetic foot infections (DFIs) are a significant health issue and a common complication among patients with diabetes. To develop antibiotic therapy for these high-risk patients, the current study evaluates the scope of DFIs and identifies the causing microbes. It also measures spectrum and antibiotic susceptibility of the pathogens isolated from adults with DFIs in Saudi Arabia. To achieve the study objectives, a cross-sectional study was implemented and the baseline characteristics for 44 patients with DFIs were defined. Optimal aerobic and anaerobic microbiological techniques were utilized to culture specimens isolated from infected foot ulcers. The standard microbiological methods were employed to identify the bacterial isolates and antibiotic susceptibility testing was conducted following the procedures of the Clinical and Laboratory Standards Institute (CLSI). Results showed that 12 microorganisms were isolated from the participants’ diabetic foot ulcers. Staphylococcus Aureus was ranked first because it appeared in 29 (65.9%) cases. Streptococcus Agalactiae was ranked second and multi-microbial infections were also found. Most of the organisms were susceptible to Vancomycin, Ciprofloxacin, and Cefalexin, but they were resistant to Methicillin, Gentamicin, and Ampicillin antibiotics. Staphylococcus Aureus was most sensitive to Ciprofloxacin, while it was resistant to Methicillin. About 10% of the isolates were multidrug-resistant. The study concludes that while Vancomycin should be used empirically for Gram-positive isolates, Ciprofloxacin can be taken into consideration for most of the Gram-negatives aerobes. Based on including various microorganisms and the advent of multidrug-resistant strains, proper culture and sensitivity testing are necessary prior to the empirical therapy.

Gram-Negative Skin and Soft Tissue Infections

Skin and soft tissue infections (SSTIs) frequently are encountered in clinical practice, and gram-negative bacilli (GNB) constitute an underrated portion of their etiology. The rate of GNB-causing SSTIs is increasing, especially with the rise in antimicrobial resistance. Although the diagnosis of SSTIs mostly is clinical, rapid diagnostic modalities can shorten the time to initiating proper therapy and improving outcomes. Novel antibiotics are active against GNB SSTIs and can be of great value in the management. This review provides an overview of the role of GNB in SSTIs and summarizes their epidemiology, risk factors, outcome, and clinical management.

A Retrospective Analysis of Microbiologic Profile of Foot Infections in Patients With Diabetic End-Stage Renal Disease

Objective

Individuals with diabetes and end-stage renal disease (ESRD) are at increased risk of foot ulceration and lower extremity amputation. Although risk factors and microbiologic analysis of diabetic foot infections ( DFIs) have been extensively studied, there are limited data available for this characteristic group.

Methods

Clinical, demographic, laboratory, microbiological data, and foot examination information were collected retrospectively regarding 94 patients with ESRD who were referred for DFI between 2006 and 2016 to hyperbaric oxygen therapy.

Results

In 6 of 94 patients with ESRD (mean age 60 years; 65 males [69.1%], 29 women [30.8%]; 91 undergoing hemodialysis [96.8%], one peritoneal dialysis [1%], two [2%] recent renal transplants), the lesions were bilateral; therefore, the evaluations were made over 100 DFIs. The most common pathogens isolated in deep wound cultures were Staphylococcus aureus and Pseudomonas aeruginosa, respectively, contributing to 27 (21.2%) and 16 (12.5%) of all 127 isolates. When the distribution of the isolates according to different Wagner grades were analyzed, it was found that the proportion of Gramnegative isolates increased statistically significantly with the ascending Wagner grade (P = .004).

Conclusion

DFIs indicate a serious complication associated with a high risk of amputation, prolonged antibiotic treatment, increased hospital and procedure demands, and the cost of health care, on patients with ESRD. The familiarization of causative pathogens underlying DFIs can aid the clinicians in the choice of appropriate empirical antibiotic treatment. This study emphasizes the need for greater attention to risk factors and the microbiologic profile of DFIs in this characteristic group.

Hypertonic glucose inhibits growth and attenuates virulence factors of multidrug-resistant Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is the most common Gram-negative pathogen responsible for chronic wound infections, such as diabetic foot infections, and further exacerbates the treatment options and cost of such conditions. Hypertonic glucose, a commonly used prolotherapy solution, can accelerate the proliferation of granulation tissue and improve microcirculation in wounds. However, the action of hypertonic glucose on bacterial pathogens that infect wounds is unclear. In this study, we investigated the inhibitory effects of hypertonic glucose on multidrug-resistant P. aeruginosa strains isolated from diabetic foot infections. Hypertonic glucose represents a novel approach to control chronic wound infections caused by P. aeruginosa.

RESULTS

Four multidrug-resistant P. aeruginosa clinical strains isolated from diabetic foot ulcers from a tertiary hospital in China and the reference P. aeruginosa PAO1 strain were studied. Hypertonic glucose significantly inhibited the growth, biofilm formation, and swimming motility of P. aeruginosa clinical strains and PAO1. Furthermore, hypertonic glucose significantly reduced the production of pyocyanin and elastase virulence factors in P. aeruginosa. The expression of major quorum sensing genes (lasI, lasR, rhlI, and rhlR) in P. aeruginosa were all downregulated in response to hypertonic glucose treatment. In a Galleria mellonella larvae infection model, the administration of hypertonic glucose was shown to increase the survival rates of larvae infected by P. aeruginosa strains (3/5).

CONCLUSIONS

Hypertonic glucose inhibited the growth, biofilm formation, and swimming motility of P. aeruginosa, as well as reduced the production of virulence factors and quorum sensing gene expression. Further studies that investigate hypertonic glucose therapy should be considered in treating chronic wound infections.

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

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

A Severe Diabetic Foot Ulcer With Intermediate Cuneiform Displacement and Multidrug-Resistant Pseudomonas aeruginosa Infection: A Rare Case Report

Diabetic foot ulcer (DFU) is considered as one of the most serious and prevailing complications of diabetes mellitus, while it is the major cause of amputations in diabetic patients. Herein, we reported an acquired severe traumatic DFU with an intermediate cuneiform hairline fracture and displacement in a 55-year old male (Grade IV of Wagner classification; Grade III of IWGDF classification). The Pseudomonas aeruginosa was identified in pus culture. Data of antibiotic susceptibility testing indicated that the isolates of Pseudomonas aeruginosa were multi-drug resistant. Routine debridement, clearing displaced intermediate cuneiform and drainage were performed to facilitate the outflow of pus and pressure mitigation. Dressing with Prontosan solution and gel was applied to the wound, and meropenem was systemically administrated in addition to effective glycemic control. The DFU has been fully healed after ~40-day treatment. For this case, clearing the displaced and fractured intermediate cuneiform is essential for the heal of the DFU in addition to the common strategy for DFU treatment, i.e., the combination of debridement, pressure mitigation, wound dressing with Prontosan, antibiotic selection and effective glycemic control. This case report might have value for the treatment of complex DFU with bone fracture and displacement, reducing the risk of amputation.

Evaluation of Serum Vitamin D Levels in Diabetic Foot Infections: A Cross-Sectional Study in a Tertiary Care Center in South India

Background

The impact of diabetic foot infections is enormous in India. Studies on vitamin D levels in diabetes mellitus foot infections are scarce. The primary objective of the present study was to compare the serum vitamin D level between diabetics with foot infections and those without foot infections and the secondary objective was to assess the association between the vitamin D level and the severity of foot infections and outcomes.

Methods

The study included 176 type 2 diabetics who attended Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India, between September 2012 and June 2014. The serum vitamin D level was measured for 88 diabetics with foot infections (Group 1) and 88 without foot infections (Group 2) using the ELISA 25OH vitamin D DIAsource kit (DIAsource ImmunoAssays S.A., Belgium) and compared. Both groups were followed up for 6 months for outcomes. The qualitative variables were analyzed using the χ2 test and the quantitative variables using the Student t test. The statistical analyses were performed using SPSS, version 17.0. A P value of less than 0.05 was considered significant.

Results

The mean serum vitamin D level was not significantly different between the two groups (P=0.306). Among the patients in Group 1 who either required amputations or died, 97.44% had subnormal vitamin D levels in contrast to 59.18% in those who were grafted or achieved wound healing (P=0.001). Among those who achieved wound healing within 6 months, 78.9% had normal vitamin D levels (P=0.0006).

Conclusion

The study found no significant difference in the serum level of vitamin D between diabetics with and without foot infections. However, vitamin D deficiency was associated with a poor outcome in diabetics with foot infections.

A Study on Isolation, Characterization, and Exploration of Multiantibiotic-Resistant Bacteria in the Wound Site of Diabetic Foot Ulcer Patients

This study collected wound swab samples from 50 diabetic patients, especially in Wagner's grade 2 (28) and grade 3 (22) foot ulcers. The samples were processed and subjected to bacterial isolation and characterization. The obtained diabetic foot ulcer (DFU) bacterial isolates were also subjected to antibiotic susceptibility assay. All the collected samples were culture positive and produced a total of 85 isolates. Monomicrobial and polymicrobial infections were observed from the collected grade 2 and 3 samples, respectively. Gram's staining and morphological analyses of the obtained bacterial colony demonstrated the presence of both Gram-positive and Gram-negative bacilli, Gram-positive cocci, and Gram-negative cocco-bacilli in the wounds of diabetic patients. The bacterial profiling of 85 isolates revealed the presence of Gram-negative bacteria such as Pseudomonas aeruginosa, Escherichia coli, Proteus spp, Acinetobacter spp, Enterobacter spp, Klebsiella pneumoniae, Citrobacter spp, K oxytoca, and Stenotrophomonas spp Gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Corynebacterium spp, and Streptococcus dysgalactiae were also identified. The predominant microbial flora found in the collected samples were Staphylococcus aureus (38%) and P aeruginosa (23.2%), followed by B subtilis (21%) and Escherichia coli (18%) and other bacteria. Furthermore, the obtained antibiotic susceptibility assay data of DFU isolates have also confirmed the distribution of multiantibiotic-resistant bacteria in the wound site of diabetic patients. The findings of the present study suggest that there is a need for the discovery of novel drug(s) to alleviate antibiotic-resistant bacterial infections in DFU patients.

Combinatorial Drug Therapy for Controlling Pseudomonas aeruginosa and Its Association With Chronic Condition of Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a major complication of diabetes mellitus, major observations of DFU cases have reported on amputation of foot region, and microbial bioburden during DFU is a major cause that affects healing of the wound regions. Pathogenic microbes are routinely isolated from these wound regions, especially Staphylococcus, Pseudomonas, Klebsiella, and Escherichia coli have been reported, whereas higher prevalence of Pseudomonas species during chronic condition in the deeper part of the wound, when left untreated, leads to gangrene. Multiple drug-resistant Pseudomonas strains are a new threat because of their biofilm-forming ability, making it more potent and incurable. Acyl homoserine lactones (AHL) are a group of signaling molecules that can regulate biofilm growth, and Las and Rhl operon generally work in tandem to initiate biofilm formation by Pseudomonas species. These signaling molecules also initiate virulence factors that correlates upregulation of inflammatory responses, and AHL can be a therapeutic target in order to prevent the efficacy of multiple drug-resistant strains that form biofilm and also can be an alternative solution against control of multiple drug-resistant strains.

Bacteriology of moderate-to-severe diabetic foot infections in two tertiary hospitals of Iran

BACKGROUND

Approximately 25% of people with diabetes will experience diabetic foot ulcers (DFUs) during their lifetime. The present study was designed to determine the type of microorganisms isolated from the DFUs and their antibiotic resistance pattern, and to determine predisposing factors contributing to antibiotic resistance at the authors' wound care clinic in Qazvin, Iran.

METHODS

A cross-sectional study was conducted from May to December 2017. One specimen for microbiological studies was obtained from the deep tissue. All demographic, clinical, and laboratory data and results of ulcer culture were collected for each case. Antimicrobial susceptibility testing to different agents was carried out using the disc diffusion method. A p value < 0.05 was considered significant.

RESULTS

95 aerobic microorganisms were isolated from 105 specimens. Among Gram-positive and negative bacteria, Staphylococcus spp. and Escherichia (E). coli were the most frequent organisms isolated, respectively. Multidrug resistant (MDR) organisms constituted up to 48.4%, with 37.5% of isolated Enterococcus spp. being VRE, 48.8% of Staphylococcus spp. being methicillin-resistant, 77.8% of isolated E. coli being ESBL and 66.7% of isolated Pseudomonas being MDR. The minimum and maximum prevalence of resistance in Gram-negative bacteria were 17.6% and 87.5% for imipenem and ceftazidime, respectively. The prevalence of Gram-negative bacilli was higher in older patients (p value = 0.039) and rose markedly in patients with a higher number of hospitalizations (p value = 0.015).

CONCLUSION

Due to emergence of antibiotic resistance pathogens, culture specimens and antibiotic sensitivity testing are essential for correct management of the DFU infections and the selection of appropriate antibiotics.

Point-of-care fluorescence imaging predicts the presence of pathogenic bacteria in wounds: a clinical study

OBJECTIVE

Bacteria in chronic wounds are invisible to the naked eye and can lead to delayed wound healing. Point-of-care bacterial fluorescence imaging illuminates a wound with 405nm light, triggering bacteria to produce red fluorescence and enabling real-time bacterial localisation. Prospective, single-blind clinical trials (clinicaltrials.gov #NCT02682069, #NCT03091361) were conducted to determine the positive predictive value (PPV) of this red fluorescence for detecting bacteria in chronic wounds.

METHOD

Lower limb chronic wounds were imaged for bacterial fluorescence using the MolecuLight i:X imaging device. Regions positive for red fluorescence were discretely sampled using either biopsy or curettage to correlate red fluorescence signals to bacterial presence and analysed via gold standard quantitative polymerase chain reaction (qPCR) or via semi-quantitative culture analysis respectively.

RESULTS

A total of 60 lower limb chronic wounds were imaged. Quantitative PCR analysis of wound tissue biopsies obtained from regions of red fluorescence yielded a PPV of 100%. Total bacterial load in these areas was ≥10⁴ CFU/g. Semi-quantitative culture analysis of curettage scrapings from regions of red fluorescence yielded a PPV of 100%, with predominately moderate or heavy bacterial growth. There were nine distinct bacterial species detected, all common pathogens in chronic wounds. Staphylococcus aureus was the most prevalent species.

CONCLUSION

Bacterial fluorescence image-guided curettage or biopsy sampling positively predicts bacterial presence in wounds at potentially harmful levels, entirely eliminating the risk of false negative sampling. Fluorescence imaging of wounds offers clinicians real-time information on a wound's bacterial burden, insight which can influence treatment decisions at the point-of care.

Insight into multidrug-resistant microorganisms from microbial infected diabetic foot ulcers

AIM

This study was undertaken to inspect the preponderance of multidrug-resistant (MDR) microorganisms in microbial infected diabetic foot ulcers (DFUs) in north Egypt. Moreover, their later impact on the patients and previous antibiotic therapies were taken into consideration.

METHODS

To accomplish this goal, twenty-two of diabetic foot patients with purulent wounds were enrolled in this prospective study. These wounds were swabbed and the antibiotics susceptibility patterns of most virulent bacteria and yeast were studied. Furthermore, bacterial and yeast strains were identified using 16S rRNA and 16S rRNA nucleotide sequences, respectively, and following their phenotypic characteristics employing the VITEK 2 system.

RESULTS

Microbial profiles showed a predominance of monomicrobial infections (77.3%), while polymicrobial infections were found in 22.7%. A total of 24 bacterial isolates (15 Gram-positive and 9 Gram-negative) and four yeast isolates were perceived. Four bacteria were selected based on their resistance toward more than six of empirical antibiotics. They were identified and deposited in GenBank as Acinetobacter baumanni MT3 (KY421195), Staphylococcus aureus MT1 (KY421197), Klebsiella pneumonia MT2 (KY421196), and Staphylococcus aureus MT4 (KY421198). On the other hand, one strain belonged to yeast was opted and identified as Candida albicans MT5 (MG851796).

CONCLUSION

These findings might effectively help to avert the severe complications of diabetic foot infections (DFIs) besides our endeavours to find new antimicrobial wound dressings.

Can we predict vascular status and culture result based through wound status in diabetic foot infection?

Diabetic foot infection (DFI) should be treated by a multidisciplinary team to prevent amputation and morbid status. As physicians encountering DFI in outpatient clinic, a proper selection of antibiotic treatment and diagnostic approach for a vascular status is essential. We retrospectively investigated the patients with DFI from 2016 to 2017. All patients were examined for vascular status, wound status, and pathologic culture preceding the treatment. No statistical significance was observed between PEDIS grade 1 and 2 and 3 and 4 in culture status and culture results. Association analysis between vascular status and other variables, such as wound score and culture results, has no significant difference. Through these results, the helpful epidemiologic result of microbiology and necessity of examination for peripheral arterial disease were verified.

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.

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.

Classification, microbiology and treatment of diabetic foot infections

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

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.

Bacterial Silver Resistance Gained by Cooperative Interspecies Redox Behavior

Silver has emerged as an important therapeutic option for wound infections in recent years due to its broad-spectrum antimicrobial activity. The silver cation (Ag⁺), but not the bulk metal (Ag⁰), is highly toxic for most microorganisms, although resistance due to genetic modification or horizontal gene transfer does occur. Pseudomonas aeruginosa, however, achieves silver resistance by producing the redox-active metabolite pyocyanin that reduces Ag⁺ to nontoxic Ag⁰ Pyocyanin also possesses broad-spectrum antimicrobial activity. Many microbial species reduce pyocyanin, which reduces molecular oxygen to antimicrobial hydrogen peroxide. In this study, it was hypothesized that both Ag⁺ and oxygen would act as competing terminal electron acceptors for pyocyanin, thus acting as a universal microbial protectant from Ag⁺ while avoiding hydrogen peroxide formation. Escherichia coli and Staphylococcus aureus efficiently reduced pyocyanin and generated hydrogen peroxide, while Ag⁺ markedly reduced the amount of hydrogen peroxide produced. Although unable to reduce directly Ag⁺ to Ag⁰ on their own, E. coli and S. aureus did so when pyocyanin was present, resulting in increased survival when exposed to Ag⁺ Coincubation experiments with either E. coli or S. aureus with P. aeruginosa demonstrated increased survival for those species to Ag⁺, but only if pyocyanin was present. These data demonstrate that microorganisms that display no intrinsic silver resistance may survive and proliferate under potentially toxic conditions, provided their environment contains a suitable redox-active metabolite-producing bacterium. Chronic wounds are often polymicrobial in nature, with pyocyanin-producing P. aeruginosa bacteria frequently being present; therefore, redox-based silver resistance may compromise treatment efforts.

Pseudomonas aeruginosa infection alters the macrophage phenotype switching process during wound healing in diabetic mice

Macrophages play critical roles in wound healing process. They switch from "classically activated" (M1) phenotype in the early inflammatory phase to "alternatively activated" (M2) phenotype in the later healing phase. However, the dynamic process of macrophage phenotype switching in diabetic wounds burdened with bacteria is unclear. In this report, Pseudomonas aeruginosa, frequently detected in diabetic foot ulcers, was inoculated into cutaneous wounds of db/db diabetic mice to mimic bacterium-infected diabetic wound healing. We observed that P. aeruginosa infection impaired diabetic wound healing and quickly promoted the expression of pro-inflammatory genes (M1 macrophage markers) tumor necrosis factor-α (tnf-α), interleukin-1β (il-1β) and il-6 in wounds. The expression of markers of M2 macrophages, including il-10, arginase-1, and ym1 were also upregulated. In addition, similar gene expression patterns were observed in macrophages isolated directly from wounds. Immunostaining showed that P. aeruginosa infection increased both the ratios of M1 and M2 macrophages in wounds compared with that in control groups, which was further confirmed by in vitro culturing macrophages with P. aeruginosa and skin fibroblast conditioned medium. However, the ratios of the expression levels of pro-inflammatory genes to anti-inflammatory gene il-10 was increased markedly in P. aeruginosa infected wounds and macrophages compared with that in control groups, and P. aeruginosa prolonged the presence of M1 macrophages in the wounds. These data demonstrated that P. aeruginosa in diabetic wounds activates a mixed M1/M2 macrophage phenotype with an excessive activation of M1 phenotype or relatively inadequate activation of M2 phenotype.