Bacterial diversity and inflammatory response at first-time visit in younger and older individuals with diabetic foot infection (DFI)

Prevalence of multidrug-resistant bacterial infections in diabetic foot ulcers: A meta-analysis

Multidrug-resistant (MDR) bacterial infections have become increasingly common in recent years due to the increased prevalence of diabetic foot ulcers (DFUs). We carried out a meta-analysis aimed at investigating the prevalence of MDR bacteria isolated from DFUs and analysing the risk factors for MDR bacterial infection in patients with DFUs. The PubMed/Medline, Web of Science, Embase, Cochrane Library, Ovid, Scopus, and ProQuest databases were searched for studies published up to November 2023 on the clinical outcomes of MDR bacteria in DFUs. The main outcome was the prevalence of MDR bacteria in DFUs. A total of 21 studies were included, representing 4885 patients from which 2633 MDR bacterial isolates were obtained. The prevalence of MDR bacteria in DFUs was 50.86% (95% confidence interval (CI): 41.92%-59.78%). The prevalence of MDR gram-positive bacteria (GPB) in DFUs was 19.81% (95% CI: 14.35%-25.91%), and the prevalence of MDR gram-negative bacteria (GNB) in DFUs was 32.84% (95% CI: 26.40%-39.62%). MDR Staphylococcus aureus (12.13% (95% CI: 8.79%-15.91%)) and MDR Enterococcus spp. (3.33% (95% CI: 1.92%-5.07%)) were the main MDR-GPB in DFUs. MDR Escherichia coli, MDR Pseudomonas aeruginosa, MDR Enterobacter spp., MDR Klebsiella pneumoniae, and MDR Proteus mirabilis were the main MDR-GNB in DFUs. The prevalence rates were 6.93% (95% CI: 5.15%-8.95%), 6.01% (95% CI: 4.03%-8.33%), 3.59% (95% CI: 0.42%-9.30%), 3.50% (95% CI: 2.31%-4.91%), and 3.27% (95% CI: 1.74%-5.21%), respectively. The clinical variables of diabetic foot ulcer patients infected with MDR bacteria and non-MDR bacteria in the included studies were analysed. The results showed that peripheral vascular disease, peripheral neuropathy, nephropathy, osteomyelitis, Wagner's grade, previous hospitalization and previous use of antibacterial drugs were significantly different between the MDR bacterial group and the non-MDR bacterial group. We concluded that there is a high prevalence of MDR bacterial infections in DFUs. The prevalence of MDR-GNB was greater than that of MDR-GPB in DFUs. MDR S. aureus was the main MDR-GPB in DFUs, and MDR E. coli was the main MDR-GNB in DFUs. Our study also indicated that peripheral vascular disease, peripheral neuropathy, nephropathy, osteomyelitis, Wagner's grade, previous hospitalization, and previous use of antibacterial drugs were associated with MDR bacterial infections in patients with DFUs.

Correlation between inflammatory factors, autophagy protein levels, and infection in granulation tissue of diabetic foot ulcer

OBJECTIVE

To observe the expression of inflammatory factors and autophagy-related proteins in granulation tissue of diabetic foot ulcer (DFU) patients and analyze their relationship with infection.

METHODS

This is a retrospective cohort study. One hundred and fifty-two patients with DFU in our hospital from July 2020 to March 2022 were selected as the DFU group, including 98 cases in infection stage group and 54 cases in infection control group. The patients were further graded as the mild (51 cases), the moderate (65 cases), and the severe infection group (36 cases) according to the Wagner grading criteria. Sixty-seven patients with foot burns during the same period were selected as the control group. The distribution of pathogenic bacteria on the ulcer surface was examined using fully automated bacterial analyzer. The expression of inflammatory factors (procalcitonin [PCT], tumor necrosis factor-α [TNF-α], and interleukin-6 [IL-6]) was valued by real-time fluorescence quantitative PCR (qRT-PCR). Protein expression was measured by immunohistochemistry (IHC). The correlation was analyzed by Pearson.

RESULTS

The surface infection of DFU patients was mostly induced by gram-negative and gram-positive bacteria, with Pseudomonas aeruginosa predominating among the Gram-negative bacteria and Staphylococcus aureus among the gram-positive bacteria. The infection stage group had higher content of PCT, TNF-α, and IL-6 and lower content of Beclin-1 and LC3 than the infection control group (p < .001). The levels of PCT, TNF-α, and IL-6 in the DFU patients with cardiovascular events were higher than those in the nonoccurrence group (p < .001). Glycated hemoglobin in patients with DFU was positively correlated with PCT, TNF-α, and IL-6 levels (p < .05), and negatively correlated with Beclin-1 and LC3 levels (p < .001).

CONCLUSION

P. aeruginosa and S. aureus were predominant bacterial in DFU infections. Inflammatory factor and autophagy protein expression were closely correlated with the degree of infection.

Impact of Psychological Distress on Physiological Indicators of Healing Prognosis in Patients with Chronic Diabetic Foot Ulcers: A Longitudinal Study

Objective: Diabetic foot ulcers (DFUs) are devastating complications of diabetes, responsible for a high number of amputations worldwide. Due to its impact on chronic inflammation, psychological distress may negatively impact the healing process. Thus, this study evaluated the influence of psychological distress on physiological indicators of healing prognosis and the potential of stress-reducing therapies for DFU healing. Approach: Patients with chronic DFU were recruited and assessed at enrollment and 2 months later. According to psychological scores at enrollment, participants were allocated into groups without (group 1) or with (group 3) psychological distress. Participants who reported clinical distress were then randomly allocated into a control (no stress-reducing intervention-group 4) or experimental (with stress-reducing interventions-group 5) group. Subsequently, indicators of healing prognosis were measured. Results: Groups 1 and 3 presented no differences in the Perfusion, Extent, Depth, Infection and Sensation score, glycated hemoglobin, or inflammatory and angiogenic markers. However, the immune cell ratio was increased by more than twofold in group 3, compared with group 1. Importantly, the expression of circulating microRNAs was significantly increased in group 3 (miR-21-5p, miR-155-5p, miR-146a-5p, and miR-221-3p [p < 0.05]), compared with group 1. Two months later, group 5 displayed a significant improvement in the Perceived Stress Scale and Hospital Anxiety and Depression Scale scores (p < 0.01), and the immune cell ratio was decreased by more than 2.5-fold. Innovation: This study helped to identify which variables and psychological interventions are more successful in promoting DFU healing. Conclusion: Psychological distress influenced clinical and physiological parameters, leading to compromised DFU healing and consequently underlining the potential of adjuvant stress-reducing approaches.

Innovative Functional Biomaterials as Therapeutic Wound Dressings for Chronic Diabetic Foot Ulcers

The imbalance of local and systemic factors in individuals with diabetes mellitus (DM) delays, or even interrupts, the highly complex and dynamic process of wound healing, leading to diabetic foot ulceration (DFU) in 15 to 25% of cases. DFU is the leading cause of non-traumatic amputations worldwide, posing a huge threat to the well-being of individuals with DM and the healthcare system. Moreover, despite all the latest efforts, the efficient management of DFUs still remains a clinical challenge, with limited success rates in treating severe infections. Biomaterial-based wound dressings have emerged as a therapeutic strategy with rising potential to handle the tricky macro and micro wound environments of individuals with DM. Indeed, biomaterials have long been related to unique versatility, biocompatibility, biodegradability, hydrophilicity, and wound healing properties, features that make them ideal candidates for therapeutic applications. Furthermore, biomaterials may be used as a local depot of biomolecules with anti-inflammatory, pro-angiogenic, and antimicrobial properties, further promoting adequate wound healing. Accordingly, this review aims to unravel the multiple functional properties of biomaterials as promising wound dressings for chronic wound healing, and to examine how these are currently being evaluated in research and clinical settings as cutting-edge wound dressings for DFU management.

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.

Clinical Features, Inflammatory Markers, and Limb Salvage in Older Adults with Diabetes-Related Foot Infections

Little information exists about diabetic foot infections (DFIs) in older patients. We hypothesize that older patients with DFIs have different clinical features and worse outcomes than younger patients. We conducted a prospective observational study consisting of a cohort of patients with diabetes and moderate to severe DFIs. Patients included in the cohort were dichotomized into two groups using percentile 75 (P75) of age as the cut-off value. Patients aged > P75 presented with more comorbidities and foot-related complications, a higher rate of peripheral arterial disease (PAD), worse renal function (higher values of blood urea nitrogen and creatinine, and lower values of estimated glomerular filtration rate), and lower values of HbA1c compared with younger patients. Infection severity, microbiological features, and inflammatory markers were similar in both groups. In the multivariate analysis, minor amputations were associated with age > P75 (OR = 2.8, 95% CI 1.3-5.9, p <0.01), necrosis (OR = 4.2, 95% CI 1.8-10.1, p < 0.01), and CRP values (OR = 1.045, 95% CI 1.018-1.073, p < 0.01). Major amputations were associated with a history of amputation (OR = 4.7, 95% CI 1.3-16.7, p = 0.01), PAD (OR = 4.3, 95% CI 1.2-14.6, p = 0.01), and albumin values (OR = 0.344, 95% CI 0.130-0.913, p = 0.03). In conclusion, limb salvage can be achieved in older patients with diabetes-related foot infections at the same rate as in younger patients, despite the fact that they have more comorbidities and foot-related complications, a higher rate of PAD, and worse renal function.

Distribution of microbes and antimicrobial susceptibility in patients with diabetic foot infections in South China

BACKGROUND

To investigate the distribution of microbes and drug susceptibility in patients with diabetic foot infections (DFI) and provide guidance for clinical empirical treatment and the rational selection of antibacterial drugs.

METHODS

Retrospective analysis of the pathogenic bacterium distribution and antimicrobial susceptibility isolated from 581 DFI patients with different Wagner grades.

RESULTS

The 534 positive samples included 473 cases (88.58%)) of monomicrobial infections and 61 cases (11.42%) of polymicrobial infections before antibiotic therapy. A total of 656 strains were cultivated, including 387 (58.99%) strains of gram-positive organisms (GPOs), 235 (35.82%) gram-negative bacilli (GNB), and 21 (3.20%) fungal strains. Polymicrobial infections mainly occurred in patients with Wagner grade 3-4 ulcers. GPOs were predominant in Wagner grades 1-3 (grade 1: 96.67%, grade 2: 76.52%, grade 3 62.81%), and the most common was Staphylococcus aureus (grade 1: 31.66%, grade 2: 33.04%, grade 3 35.53%). GNB were predominant in grades 4-5 (grade 4: 51.46%, grade 5:60%), and the most common GNB in Wagner grades 4-5 was Proteus (grade 4:27.88%, grade 5: 42.86%), while the most common GPO was Enterococcus (grade 4:34.48%, grade 5:25.00%). Staphylococcus (including MRSA) and Enterococcus were still highly sensitive to vancomycin, linezolid, and tigecycline. Most GNB were still highly sensitive to meropenem, tigecycline, ertapenem, and amikacin. Proteus was most sensitive to amikacin (97.14%), followed by meropenem (92%) and ertapenem (80%).

CONCLUSION

The distribution of microbes and antimicrobial susceptibility in DFI patients varied with different Wagner grades. The most appropriate antimicrobial therapy should be selected based on the pathogen culture and antimicrobial susceptibility.

Keeping an eye on the diabetic foot: The connection between diabetic eye disease and wound healing in the lower extremity

Diabetic eye disease is strongly associated with the development of diabetic foot ulcers (DFUs). DFUs are a common and significant complication of diabetes mellitus (DM) that arise from a combination of micro- and macrovascular compromise. Hyperglycemia and associated metabolic dysfunction in DM lead to impaired wound healing, immune dysregulation, peripheral vascular disease, and diabetic neuropathy that predisposes the lower extremities to repetitive injury and progressive tissue damage that may ultimately necessitate amputation. Diabetic retinopathy (DR) is caused by cumulative damage to the retinal mic-rovasculature from hyperglycemia and other diabetes-associated factors. The severity of DR is closely associated with the development of DFUs and the need for lower extremity revascularization procedures and/or amputation. Like the lower extremity, the eye may also suffer end-organ damage from macrovascular compromise in the form of cranial neuropathies that impair its motility, cause optic neuropathy, or result in partial or complete blindness. Additionally, poor perfusion of the eye can cause ischemic retinopathy leading to the development of proliferative diabetic retinopathy or neovascular glaucoma, both serious, vision-threatening conditions. Finally, diabetic corneal ulcers and DFUs share many aspects of impaired wound healing resulting from neurovascular, sensory, and immunologic compromise. Notably, alterations in serum biomarkers, such as hemoglobin A1c, ceruloplasmin, creatinine, low-density lipoprotein, and high-density lipoprotein, are associated with both DR and DFUs. Monitoring these parameters can aid in prognosticating long-term outcomes and shed light on shared pathogenic mechanisms that lead to end-organ damage. The frequent co-occurrence of diabetic eye and foot problems mandate that patients affected by either condition undergo reciprocal comprehensive eye and foot evaluations in addition to optimizing diabetes management.

Factors Associated with Infection Severity of Diabetic Foot Ulcers: A Cross-Sectional Study

Background: Infection in the ulcerated foot is a foremost cause of morbidity, constituting the biggest proportion of hospitalization and amputation among patients with diabetic foot ulcers. Assessment of infection severity lays a foundation for making treatment decisions, for which the IDSA/IWGDF classification is recommended. Different factors may cause various severity of infection. However, few investigations have been conducted concerning factors associated with infection severity of diabetic foot ulcers. Objective: To investigate factors associated with infection severity of diabetic foot ulcers. Methods: This cross-sectional study involved 150 subjects hospitalized in the Department of Endocrinology of Sun Yat-sen Memorial Hospital in Guangdong Province between July 2020 and September 2021. The IDSA/IWGDF classification was adopted to assess ulcer infection severity. Demographic and disease information, laboratory reports, and ulcer assessment results were evaluated for an association with the infection severity. The generalized linear model was performed to conduct multivariate analyses of the factors associated with the severity of foot infection. Results: The prevalence of mild, moderate, and severe infected diabetic foot was 23.3%, 64.7% and 10.2%, respectively. The results of generalized linear models showed a correlation between Alb (OR = -1.74, 95%CI1.12-6.58, p = .023), CRP (OR = 2.13, 95%CI1.38-7.21, p = .014), PCT (OR = 2.01, 95%CI1.29-7.64, p = .013), microbial type (OR = 2.04, 95%CI1.43-7.83, p = .004) and ulcer infection severity. Conclusion: Alb, CRP, PCT and microbial type were among the factors influencing infection severity of diabetic foot ulcers.

Limb Salvage in Severe Diabetic Foot Infection

Severe diabetic foot infections (DFI) are both limb threatening and life threatening and associated with negative impact on health-related quality of life. Most severe DFIs require surgical intervention, and the goal of treatment should be preservation of limb function in addition to eradication of infection. Minor amputations are required in approximately 40% and major amputations in approximately 20% of patients. Significant risk factors for lower extremity amputation included male gender, smoking, previous amputation, osteomyelitis, peripheral artery disease, retinopathy, severe infections, gangrene, neuroischemic diabetic foot infections, leukocytosis, positive wound cultures, and isolation of gram-negative bacteria.

Changing Bacterial Etiology and Antimicrobial Resistance Profiles as Prognostic Determinants of Diabetic Foot Infections: A Ten-Year Retrospective Cohort Study

Background: In this single-center study, we analyzed a retrospective cohort of patients with diabetic foot infections (DFIs) between 2011 and 2020. Patients and Methods: The first and second five-year periods were compared. A poor prognosis was defined as a primary composite end point including re-infection, major amputation, or mortality at six months. Results: A total of 484 patients were enrolled. Overall, 269 patients had the primary composite end point. A substantial decrease was detected in the second five-year period in terms of re-infection (n = 132, 66.0% vs. n = 68, 23.9%; p < 0.001) and mortality (n = 22, 11.0% vs. n = 7, 2.5%; p < 0.001). A total of 798 micro-organisms were isolated from 484 patients. A substantial increase was detected in polymicrobial infections (48.5% vs. 65.1%; p = 0.001) as well as Streptococcus spp. (2.5% vs. 9.2%; p = 0.003), Corynebacterium spp. (9.5% vs. 22.9%; p < 0.001), and extended-spectrum β-lactamase (ESBL) producing Escherichia coli (3.0% vs. 12.7%; p < 0.001) in the second five-year period, whereas the prevalence of multi-drug-resistanct (MDR) Pseudomonas aeruginosa (17.0% vs. 10.2%; p = 0.029) and carbapenem-resistant Acinetobacter baumannii (7.5% vs. 2.8%; p = 0.017) decreased. Multivariable regression analysis revealed that MDR Pseudomonas aeruginosa (odds ratio [OR], 1.917; 95% confidence interval [CI], 1.074-3.420; p = 0.028) and carbapenem-resistant Acinetobacter baumannii (OR, 3.069; 95% CI, 1.114-8.453; p = 0.030) were independent predictors for poor prognosis. Conclusions: This 10-year cohort study provides reassuring information about the changing epidemiology of DFIs and the prognostic determinants in patients with DFIs.

Microbiology of Diabetic Foot Infections in a Tertiary Care Hospital in São Paulo, Brazil

Diabetic foot infections (DFIs) are one of the causes of hospitalization in diabetic patients and, when this occurs, empirical antibiotic therapy is necessary. We have conducted a retrospective study of patients with DFI that required hospitalization to evaluate microbiologic profile and the susceptibility pattern of these infections. We evaluated 320 patients, of which 223 (69.7%) were male with a media age of 71 years with 276 isolates. Gram-positive bacteria were responsible for 188 (68.1%) of the isolates, while Gram-negative bacilli were responsible for 88 (31.9%). E. faecalis was the most prevalent pathogen, followed by S. aureus and coagulase negative Staphylococci. Among Gram-negative pathogens, P. aeruginosa was the most prevalent agent. Regarding the susceptibility profile, we found ampicillin-sensitive enterococci in 89% of the cases, oxacillin-sensitive S. aureus in 47%, but in coagulase-negative staphylococci, oxacillin was sensible only in 20%. The susceptibility profile of Gram-negatives was very good with 76% susceptibility of P. aeruginosa to ceftazidime and meropenem. The other prevalent Enterobacterales had great susceptibility to ceftazidime, piperacillin-tazobactam and 100% susceptibility to meropenem, with the exception of K. pneumoniae, which had 75% susceptibility to meropenem. Knowledge of microbiological profile and susceptibility patterns of patients with DFIs is useful to guide empirical therapy.

The Antimicrobial Effects of Bacterial Cellulose Produced by Komagataeibacter intermedius in Promoting Wound Healing in Diabetic Mice

As a conventional medical dressing, medical gauze does not adequately protect complex and hard-to-heal diabetic wounds and is likely to permit bacterial entry and infections. Therefore, it is necessary to develop novel dressings to promote wound healing in diabetic patients. Komagataeibacter intermedius was used to produce unmodified bacterial cellulose, which is rarely applied directly to diabetic wounds. The produced cellulose was evaluated for wound recovery rate, level of inflammation, epidermal histopathology, and antimicrobial activities in treated wounds. Diabetic mices' wounds treated with bacterial cellulose healed 1.63 times faster than those treated with gauze; the values for the skin indicators in bacterial cellulose treated wounds were more significant than those treated with gauze. Bacterial cellulose was more effective than gauze in promoting tissue proliferation with more complete epidermal layers and the formation of compact collagen in the histological examination. Moreover, wounds treated with bacterial cellulose alone had less water and glucose content than those treated with gauze; this led to an increase of 6.82 times in antimicrobial protection, lower levels of TNF-α and IL-6 (39.6% and 83.2%), and higher levels of IL-10 (2.07 times) than in mice wounds treated with gauze. The results show that bacterial cellulose produced using K. intermedius beneficially affects diabetic wound healing and creates a hygienic microenvironment by preventing inflammation. We suggest that bacterial cellulose can replace medical gauze as a wound dressing for diabetic patients.

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.

Bioactive Antimicrobial Peptides as Therapeutic Agents for Infected Diabetic Foot Ulcers

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