Risk factors for methicillin-resistant Staphylococcus aureus in diabetic foot infections

Deciphering Diabetic Foot Wounds: A Comprehensive Review on Classification, Multidrug Resistance, Microbial Insights, Management & Treatment Strategies, and Advanced Diagnostic Tools

Diabetic foot wounds and infections pose a significant and evolving challenge in diabetes care. Diabetic wound healing has become a major global concern for a very long time. Continuous research has been conducted to increase the healing process in diabetic ulcers to the rate of amputation. Wound healing is prolonged in diabetic patients due to various conditions, such as high glucose levels, neuropathy, poor blood circulation, and prolonged inflammation around the limbs, which causes the healing to be delayed compared to normal patients. Understanding the complexity of chronic foot wounds and the management and proper treatment would lead to a decrease in the risk of amputation. The medical team all over the world is constantly researching to lower the risk. This review paper offers a compelling journey through the multifaceted world of diabetic foot wounds and infections. It underscores the urgency of understanding classification, tackling multidrug resistance, and harnessing microbial insights to revolutionize the treatment and management of diabetic foot complications. Furthermore, it unveils state-of-the-art diagnostics, heralding a brighter future in the battle against this debilitating complication of diabetes.

Emerging Frontiers in In Situ Forming Hydrogels for Enhanced Hemostasis and Accelerated Wound Healing

With a surge in the number of accidents and chronic wounds worldwide, there is a growing need for advanced hemostatic and wound care solutions. In this regard, in situ forming hydrogels have emerged as a revolutionary biomaterial due to their inherent properties, which include biocompatibility, biodegradability, porosity, and extracellular matrix (ECM)-like mechanical strength, that render them ideal for biomedical applications. This review demonstrates the advancements of in situ forming hydrogels, tracing their evolution from injectable to more sophisticated forms, such as sprayable and 3-D printed hydrogels. These hydrogels are designed to modulate the pathophysiology of wounds, enhancing hemostasis and facilitating wound repair. The review presents different methodologies for in situ forming hydrogel synthesis, spanning a spectrum of physical and chemical cross-linking techniques. Furthermore, it showcases the adaptability of hydrogels to the dynamic requirements of wound healing processes. Through a detailed discussion, this article sheds light on the multifunctional capabilities of these hydrogels such as their antibacterial, anti-inflammatory, and antioxidant properties. This review aims to inform and inspire continued advancement in the field, ultimately contributing to the development of sophisticated wound care solutions that meet the complexity of clinical needs.

Methicillin-resistant Staphylococcus aureus in diabetic and non-diabetic foot infections

To identify the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection, reinfection and clinical outcomes. Four hundred forty-six patients that were admitted to the hospital with moderate or severe foot infections were retrospectively reviewed. Tissue and bone cultures were obtained from the index hospital admission. Conversion was defined as methicillin susceptible Staphylococcus aureus in the first culture and subsequently MRSA when there was a reinfection. The incidence of MRSA was 7.8% (n = 35), with no significant difference between soft tissue infections (7.7%) and osteomyelitis (8.0%). MRSA incidence was 9.4 times higher in non-diabetics (23.8% vs. 3.2%, p = <0.01). The incidence of reinfection was 40.8% (n = 182). Conversion to MRSA was seen in 2.2% (n = 4) total, occurring in 5.4%. Non-diabetics were 20.1 times more likely to have MRSA reinfection than people with diabetes (28.6% vs. 1.9%, p < 0.001). MRSA patients had a higher proportion of healed wounds (82.4% vs. 69.3%, p = 0.02). There were no differences in other clinical outcomes in MRSA vs. other infections in reinfection (28.6% vs. 24.3%, p = 0.11), amputation (48.6% vs. 52.0%, p = 0.69) or hospitalization (28.6% vs. 42.6, p = 0.11). The incidence of MRSA for the first infection (7.8%), reinfection (6.0%) and conversion to MRSA (2.2%) was low. MRSA was 9.4 times more common in people without diabetes.

MRSA infection, re-infection and clinical outcomes in diabetic foot infections

The aim was to investigate methicillin-resistant Staphylococcus aureus (MRSA) incidence, conversion and outcomes in diabetic foot infections (DFIs). This is a pooled patient-level analysis of combined data sets from two randomised clinical trials including 219 patients admitted to the hospital with moderate or severe DFIs. Intraoperative bone and tissue cultures identified bacterial pathogens. We identified pathogens at index infections and subsequent re-infections. We identified MRSA conversion (MSSA to MRSA) in re-infections. MRSA incidence in index infections was 10.5%, with no difference between soft tissue infections (STIs) and osteomyelitis (OM). MRSA conversion occurred in 7.7% of the re-infections in patients who initially had MSSA in their cultures. Patients with re-infection were 2.2 times more likely to have MRSA compared to the first infection (10.5% vs. 25.8%, relative risk [RR] = 2.2, p = 0.001). Patients with MRSA had longer antibiotic treatment during the 1-year follow-up, compared to other pathogens (other 49.8 ± 34.7 days, MRSA 65.3 ± 41.5 days, p = 0.04). Furthermore, there were no differences in healing, time to heal, length of stay, re-infection, amputation, re-ulceration, re-admission, surgery after discharge and amputation after discharge compared to other pathogens. The incidence of MRSA at the index was 10.5% with no difference in STI and OM. MRSA incidence was 25.8% in re-infections. The RR of having MRSA was 2.2 times higher in re-infections. Patients with MRSA used more antibiotics during the 1-year follow-up. Furthermore, there were no differences in clinical outcomes compared to other bacterial pathogens.

The Global Prevalence of Methicillin-Resistant Staphylococcus Aureus in Patients with Diabetic Foot Ulcers: A Systematic Review and Meta-Analysis

Objective

Diabetic foot ulcer (DFU) frequently leads to infections, with infected DFUs being a common cause of amputation. Infection by methicillin-resistant Staphylococcus aureus (MRSA) notably increases the necessity for amputation and surgical debridement in affected individuals. Consequently, determining the prevalence and trends of MRSA in patients with DFU is of critical importance. This study aimed to assess the global prevalence and to identify trends in the occurrence of MRSA in tissue or wound swab samples from DFU patients.

Methods

We conducted a comprehensive literature search across PubMed, Embase, Scopus, and Ovid, spanning from the inception of these databases to July 2023, imposing no language restrictions. The inclusion criteria required that the studies report on 30 or more patients with DFU. Additionally, we categorized our analysis based on geographic region, publication date, and the economic status of the patient's domicile. Our primary endpoint was to ascertain the prevalence of MRSA in DFUs. This systematic review has been registered at (https://www.crd.york.ac.uk/prospero/), with the identifier CRD 42023444360.

Results

Our analysis encompassed 40 studies involving 12,924 patients across 20 countries. We found that the overall prevalence of MRSA in DFU was 17% (95% Confidence Interval [CI] 0.14-0.20). Regional prevalence varied significantly: in South America, it was 61% (95% CI 0.46-0.76), in North America 20% (95% CI 0.12-0.27), in Europe 19% (95% CI 0.14-0.25), in Africa 13% (95% CI 0.06-0.20), and in other subgroups 11% (95% CI 0.08-0.15). The prevalence of MRSA in DFUs also differed according to the economic status of the countries: 19% (95% CI 0.15-0.23) in high-income countries, 24% (95% CI 0.1-0.37) in upper-middle-income countries, 11% (95% CI 0.07-0.15) in lower-middle-income countries, and 20% (95% CI 0.13-0.27) in low-income countries. Notably, there has been a decline in MRSA prevalence, from 25% before 2010 to 9% thereafter.

Conclusion

This meta-analysis reveals a decreasing yet still significant global prevalence of MRSA in DFUs. This trend has important implications for antimicrobial resistance and underscores the need for developing targeted programs focusing on infection prevention and exploring alternative therapeutic strategies.

Nasal MRSA carriage is a risk factor for development of antibiotic resistance in diabetic foot ulcers and is significantly higher than diabetic and non-diabetic individuals without foot ulcer

BACKGROUND

Diabetic foot ulcer (DFU) is a major complication of diabetes often impacted by polymicrobial infection in the wound site. Diabetic patients are immunocompromised in nature and hence vulnerable to infection once the skin barrier is breached. Microbiological culture-based methods show that Staphylococcus aureus (SA) is the most frequently isolated bacteria from the DFU wounds. SA and its most clinically important antibiotic resistant variant methicillin-resistant S. aureus (MRSA) are commonly found in the nasal vestibule and colonization of SA as well as MRSA in any wound site can aggravate the condition. We hypothesize that the presence of nasal MRSA carriage can serve as a potential risk factor contributing to the emergence of antibiotic resistance in diabetic foot ulcer wounds.

METHODS

In the present study, we have compared the carriage of SA and MRSA in nasal cavity and foot skin among DFU patients (D+F+, n = 50), diabetic patients without any ulcer (D+F-, n = 50), and healthy controls (D-F-, n = 40) by using bacterial culture and PCR based methods. The D+F+, D+F- and D-F-individuals were further categorized based on the presence or absence of MRSA and clinical parameters were compared between MRSA+ ve and MRSA-ve individuals in each of the three groups mentioned above.

RESULTS

Our results show that, (a) nasal MRSA carriage is significantly higher (p < 0.05) in D+F+ group than the D+F- and D-F- and significantly associated with wound MRSA carriage in D+ F+ individuals (O.R. = 4.09; 95% C.I. = 1.12-15.05) and (b) the HbA1C level is significantly higher (p < 0.02) in wound MRSA positive, compared to MRSA negative D+F+ patients. Interestingly more than half of the MRSA (64%) isolated from DFU wound were identified to be multidrug resistant.

CONCLUSION

These findings strongly suggest that nasal MRSA carriage can act as a risk factor for development of antibiotic resistance in diabetic foot ulcers and it is therefore important to screen nasal and wound sites of these patients regularly. We have also developed a rapid multiplex PCR assay to detect MRSA from clinical isolates or microbial DNA isolated from clinical samples in the hospital settings.

What’s old is new again: Insights into diabetic foot microbiome

Diabetes is a chronic disease that is considered one of the most stubborn global health problems that continues to defy the efforts of scientists and physicians. The prevalence of diabetes in the global population continues to grow to alarming levels year after year, causing an increase in the incidence of diabetes complications and health care costs all over the world. One major complication of diabetes is the high susceptibility to infections especially in the lower limbs due to the immunocompromised state of diabetic patients, which is considered a definitive factor in all cases. Diabetic foot infections continue to be one of the most common infections in diabetic patients that are associated with a high risk of serious complications such as bone infection, limb amputations, and life-threatening systemic infections. In this review, we discussed the circumstances associated with the high risk of infection in diabetic patients as well as some of the most commonly isolated pathogens from diabetic foot infections and the related virulence behavior. In addition, we shed light on the different treatment strategies that aim at eradicating the infection.

Impact of Nares Swabs in the Operative Management of Distal Lower Extremity Infections

Associations between nares surveillance cultures and lower extremity wound cultures remains a topic of discussion in the literature and in clinical practice. Reports are limited due to the questionable accuracy of bedside foot cultures. A retrospective review of our institution's lower extremity wounds requiring surgical management distal to the tibial tuberosity was conducted. Deep intraoperative tissue cultures collected in a sterile operating field were referenced against nares cultures from the same hospitalization. Accuracy, sensitivity, and specificity of nares cultures for predicting methicillin-resistant Staphylococcus aureus (MRSA) infection were determined. Four hundred and forty unique patients with both nares and wound cultures met inclusion criteria. Comorbid diagnoses revealed 66.82%, 30.68%, and 32.27% of patients had diabetes mellitus, chronic kidney disease, and/or peripheral arterial disease, respectively. Sensitivity and specificity were found to be 53.13% and 96.13%, respectively. Prevalence of MRSA in a lower extremity wound was 14.9%, and accuracy of nares culture was 90.04% (CI: 86.91%-92.65%). A review of 30 false negative cases was conducted. Using exclusion criteria of a hospital admission within 60 days of presentation, history of MRSA infection, and/or presentation from a long-term care facility, negative predictive value of MRSA nares colonization was 99.51%. A case of necrotizing fasciitis accounted for one outlier. This data demonstrates that nares surveillance swabs have excellent diagnostic performance in ruling out MRSA infections in foot and ankle wounds. Further analysis is required to determine whether this performance is improved in specialized subgroups or dependent on temporal proximity.

Bacterial Interactions in the Context of Chronic Wound Biofilm: A Review

Chronic wounds, defined by their resistance to care after four weeks, are a major concern, affecting millions of patients every year. They can be divided into three types of lesions: diabetic foot ulcers (DFU), pressure ulcers (PU), and venous/arterial ulcers. Once established, the classical treatment for chronic wounds includes tissue debridement at regular intervals to decrease biofilm mass constituted by microorganisms physiologically colonizing the wound. This particular niche hosts a dynamic bacterial population constituting the bed of interaction between the various microorganisms. The temporal reshuffle of biofilm relies on an organized architecture. Microbial community turnover is mainly associated with debridement (allowing transitioning from one major representant to another), but also with microbial competition and/or collaboration within wounds. This complex network of species and interactions has the potential, through diversity in antagonist and/or synergistic crosstalk, to accelerate, delay, or worsen wound healing. Understanding these interactions between microorganisms encountered in this clinical situation is essential to improve the management of chronic wounds.

Exploring the Role of Staphylococcus aureus in Inflammatory Diseases

Staphylococcus aureus is a very common Gram-positive bacterium, and S. aureus infections play an extremely important role in a variety of diseases. This paper describes the types of virulence factors involved, the inflammatory cells activated, the process of host cell death, and the associated diseases caused by S. aureus. S. aureus can secrete a variety of enterotoxins and other toxins to trigger inflammatory responses and activate inflammatory cells, such as keratinocytes, helper T cells, innate lymphoid cells, macrophages, dendritic cells, mast cells, neutrophils, eosinophils, and basophils. Activated inflammatory cells can express various cytokines and induce an inflammatory response. S. aureus can also induce host cell death through pyroptosis, apoptosis, necroptosis, autophagy, etc. This article discusses S. aureus and MRSA (methicillin-resistant S. aureus) in atopic dermatitis, psoriasis, pulmonary cystic fibrosis, allergic asthma, food poisoning, sarcoidosis, multiple sclerosis, and osteomyelitis. Summarizing the pathogenic mechanism of Staphylococcus aureus provides a basis for the targeted treatment of Staphylococcus aureus infection.

Predictive Value of MRSA Nares Colonization in Diabetic Foot Infections: A Systematic Review and Bivariate Random Effects Meta-Analysis

The primary objective of this study was to assess the negative predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs in MRSA diabetic foot infections. MEDLINE and Cochrane Library were searched from inception to May 1, 2020. The following search string was used: (methicillin-resistant S. aureus OR MRSA) AND (nasal OR nares) AND (diabetic OR foot OR diabetic foot infections). All studies that contained data comparing MRSA nasal swab positivity to wound cultures from diabetic foot infections and met the inclusion criteria were included. Among the 86 relevant studies, 6 studies with 8706 diabetic patients were included. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline extension for Diagnostic Test Accuracy reviews was followed. The primary meta-analysis outcomes were the negative and positive predictive values of MRSA nasal swabs for MRSA diabetic foot infections. The pooled specificity and pooled sensitivity were determined by generating hierarchical summary receiver characteristic operating curves. In the bivariate meta-analysis, involving the 6 studies, pooled sensitivity and specificity was 41.7% (95% confidence interval = 32.9, 51) and 94.1% (95% confidence interval = 89.5, 96.8), respectively. In low-moderate MRSA prevalence levels (<15%), negative predictive value of MRSA nasal swab was >90% and positive predictive value was <55%. This meta-analysis suggests that in patients with diabetic foot infections, the nasal swab MRSA screen has a poor positive predictive value but an excellent negative predictive value in regions of low to moderate prevalence of MRSA diabetic foot infections.

Emerging Diabetic Foot Ulcer Microbiome Analysis Using Cutting Edge Technologies

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

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Topical Application of Ozonated Oils for the Treatment of MRSA Skin Infection in an Animal Model of Infected Ulcer

Simple Summary

Methicillin-resistant Staphylococcus aureus is often found in skin lesions infected in particular in diabetic foot ulcers, in which the prevalence can reach 40%. Clinical methicillin-resistant Staphylococcus aureus is generally resistant to most classes of antibiotics and therefore it is necessary to develop new antimicrobial agents. Ozone has a recognized bactericidal activity and has been widely used as a clinical therapeutic agent for chronic wounds, such as ulcers and other injuries, due to its ability to heal wounds. This is a preliminary study that reports the effectiveness of ozonated oils on the eradication of skin infection in vivo. The study provides further insights into the antibacterial effect of ozone in infected skin ulcers in diabetic rats and also, the potential wound healing effect of ozonated oils. Furthermore, this is the first study investigating the efficacy of ozone in the eradication of diabetic foot ulcers infected by methicillin-resistant Staphylococcus aureus. Our results indicate that topical application of ozonated oils infected skin in rats have significant antimicrobial activity as well as wound healing capacity. Achieving the healing of infected diabetic foot wounds has become a challenge and ozonated oils may be used to treat these infections.

Abstract

Diabetic foot ulcers are a common cause of morbidity in diabetic patients. One of the main pathogens found in these ulcers is methicillin-resistant Staphylococcus aureus (MRSA). MRSA often carries resistance to several classes of antibiotics and their infections are becoming harder to treat. Therefore, new alternatives are urgently needed. Thus, this study aimed to investigate the capacity of topical ozonated oil application on the treatment of early-stage skin infected with MRSA in an animal model. Ozonated oil was prepared from a mixture of oils subjected to a gas stream of O₂/O₃ mixture. Sixteen Wistar rats were inoculated by an intradermic injection of MRSA suspension, producing an abscess lesion. After 3 days, the skin epidermis was removed to open the wound. Group 1 received an application of oil mixture without ozone treatment and Group 2 received an application of ozonated oil. After the treatment period, skin was collected, colony-forming units (CFU) of bacteria were quantified and the histological analysis of the skin was carried out. Skin samples from the control 1 and 2 had a bacterial load was of 1.1 × 10⁵ and 5.7 × 10³ CFU/mL, respectively. Group 2 showed better wound healing from mild to moderate epidermal regeneration. Topical application of ozonated vegetable oil in MRSA-infected skin in rats showed a small reduction of the bacterial load and better wound healing.

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.

Skin and Soft Tissue Infections in Patients with Diabetes Mellitus

Skin and soft tissue infections are common in diabetics. Diabetic foot infection usually results from disruption of the skin barrier, trauma, pressure, or ischemic wounds. These wounds may become secondarily infected or lead to development of adjacent soft tissue or deeper bone infection. Clinical assessment and diagnosis of these conditions using a multidisciplinary management approach, including careful attention to antibiotic selection, lead to the best outcomes in patient care.

Risk factors for methicillin-resistant Staphylococcus aureus and extended-spectrum ß-lactamase producing Enterobacterales in patients with diabetic foot infections requiring hospital admission

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) may complicate the treatment of diabetic foot infections (DFIs). The aim of this study was to determine the risk factors for these pathogens in DFIs.

METHODS

This was a prospective observational study of 167 consecutive adult patients with DFIs. The diagnosis and severity of DFIs were based on the Infectious Disease Society of America (IDSA) classification system. Multivariate analyses were performed in order to identify risk factors for MRSA and ESBL-E infections.

RESULTS

S. aureus was the most isolated pathogen (n=82, 37.9 %) followed by Escherichia coli (n= 40, 18.5%). MRSA accounted for 57.3% of all S. aureus and 70% of Klebsiella pneumoniae and 25% of E. coli were ESBL producers, respectively. Deep ulcer [OR 8,563; 95% CI (1,068-4,727)], previous use of fluoroquinolones [OR 2,78; 95% CI (1,156-6,685)] and peripheral vasculopathy [OR 2,47; 95% CI (1.068-4.727)] were the independent predictors for MRSA infections; and osteomyelitis [OR 6,351; 95% CI (1,609-25,068)] and previous use of cephalosporins [OR 5,824; 95% CI (1,517-22,361)] for ESBL-E infections.

CONCLUSIONS

MRSA and ESBL-E have adquired a great clinical relevance in DFIs. The availability of their risk factors is very convenient to choose the empirical treatment in severe forms.

Diabetic Foot Infections: Local Prevalence of and Case-Control Study of Risk Factors for Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa

We identified deep diabetic foot infections by culture and conducted a case–control study examining the risk factors for moderate to severe methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PsA) diabetic foot infections. Our MRSA prevalence was lower than literature values; PsA was higher. Gangrene may be predictive of Pseudomonas infection.

Challenges and New Therapeutic Approaches in the Management of Chronic Wounds

Chronic non-healing wounds are estimated to cost the US healthcare $28-$31 billion per year. Diabetic ulcers, arterial and venous ulcers, and pressure ulcers are some of the most common types of chronic wounds. The burden of chronic wounds continues to rise due to the current epidemic of obesity and diabetes and the increase in elderly adults in the population who are more vulnerable to chronic wounds than younger individuals. This patient population is also highly vulnerable to debilitating infections caused by opportunistic and multi-drug resistant pathogens. Reduced microcirculation, decreased availability of cytokines and growth factors that promote wound closure and healing, and infections by multi-drug resistant and biofilm forming microbes are some of the critical factors that contribute to the development of chronic non-healing wounds. This review discusses novel approaches to understand chronic wound pathology and methods to improve chronic wound care, particularly when chronic wounds are infected by multi-drug resistant, biofilm forming microbes.

A retrospective analysis of the microbiology of diabetic foot infections at a Scottish tertiary hospital

Background

This study represents the first Scottish retrospective analysis of the microbiology of diabetic foot infections (DFIs). The aims were to compare the microbiological profile of DFIs treated at a Scottish tertiary hospital to that in the literature, gather data regarding antimicrobial resistance and investigate potential trends between the microbiological results and nature or site of the clinical sample taken and age or gender of the patients.

Methods

A retrospective analysis of wound microbiology results was performed, data were obtained from one multidisciplinary outpatient foot clinic during the 12 months of the year 2017. Seventy-three patients and 200 microbiological investigations were included. In cases of soft tissue infection, the deepest part of a cleansed and debrided wound was sampled. In cases of osteomyelitis a bone biopsy was obtained. Factors influencing the pattern of microbial growth or prevalence of Staphylococcus aureus were investigated.

Results

Of the 200 microbiological investigations, 62% were culture positive, of which 37.9% were polymicrobial and 62.1% monomicrobial. Among the monomicrobial results (n = 77), most were Gram positive isolates (96.1%) and the most frequently isolated bacteria was S. aureus (84.4%). No methicillin-resistant S. aureus was reported. The prevalence of S. aureus in DFIs was associated with increasing age (p = 0.021), but no evidence of association with gender, anatomical sample site or sample material was found.

Conclusion

The microbiological profile of DFIs in Scotland resembles that reported elsewhere in the UK. In this context, Gram positive organisms, primarily S. aureus, are most frequently isolated from DFIs. The S. aureus isolates identified were largely susceptible to antibiotic therapy. An association between increasing patient age and the prevalence of S. aureus in DFIs was observed.

Emergence of community-acquired methicillin-resistant Staphylococcus aureus EMRSA-15 clone as the predominant cause of diabetic foot ulcer infections in Portugal

Methicillin-resistant Staphylococcus aureus (MRSA) are often found in infected diabetic foot ulcers, in which the prevalence may reach 40%. These complications are one of the main causes of morbidity in diabetic patients. The objectives of this study were to investigate the prevalence and antimicrobial resistance of MRSA strains in infected diabetic foot ulcers and to characterize their genetic lineages. Samples collected from 42 type 2 diabetic patients, presenting infected foot ulcers, were seeded onto ORSAB plates with 2 mg/L of oxacillin for MRSA isolation. Susceptibility to 14 antimicrobial agents was tested by the Kirby-Bauer disk diffusion method. The presence of resistance genes, virulence factors, and the immune evasion cluster system was studied by PCR. All isolates were characterized by MLST, accessory gene regulator (agr), spa, and staphylococcal chromosomal cassette mec (SCCmec) typing. Twenty-five MRSA strains were isolated. All isolates showed resistance to penicillin and cefoxitin. Sixteen isolates showed phenotypic resistance to erythromycin being 7 co-resistant to clindamycin. Resistance to trimethoprim-sulfamethoxazole was found in 2 isolates harboring the dfrA and dfrG genes. The IEC genes were detected in 80% of isolates, 16 of which were ascribed to IEC-type B. Isolates were assigned to 12 different spa types. The MLST analysis grouped the isolates into 7 sequence types being the majority (68%) ascribed to SCCmec type IV. In this study, there was a high prevalence of the EMRSA-15 clone presenting multiple resistances in diabetic foot ulcers making these infections complicated to treat leading to a higher morbidity and mortality in diabetic patients.

The prevalence of methicillin-resistant Staphylococcus aureus among diabetic patients: a meta-analysis

AIMS

Diabetic patients have multiple risk factors for colonisation with methicillin-resistant Staphylococcus aureus (MRSA), a nosocomial pathogen associated with significant morbidity and mortality. This meta-analysis was conducted to estimate the prevalence of MRSA among diabetic patients.

METHODS

The MEDLINE, Embase, BIOSIS, and Web of Science databases were searched for studies published up to May 2018 that reported primary data on the prevalence of MRSA in 10 or more diabetic patients. Two authors independently assessed study eligibility and extracted the data. The main outcomes were the pooled prevalence rates of MRSA colonisation and infection among diabetic populations.

RESULTS

Eligible data sets were divided into three groups containing data about the prevalence of MRSA colonisation or in diabetic foot or other infections. From 23 data sets, the prevalence of MRSA colonisation among 11577 diabetics was 9.20% (95% CI, 6.26-12.63%). Comparison of data from 14 studies that examined diabetic and non-diabetic patients found that diabetics had a 4.75% greater colonisation rate (P < 0.0001). From 41 data sets, the prevalence of MRSA in 10994 diabetic foot infection patients was 16.78% (95% CI, 13.21-20.68%). Among 2147 non-foot skin and soft-tissue infections, the MRSA prevalence rate was 18.03% (95% CI, 6.64-33.41).

CONCLUSIONS

The prevalence of MRSA colonisation among diabetic patients is often higher than among non-diabetics; this may make targeted screening attractive. In the UK, many diabetic patients may already be covered by the current screening policies. The prevalence and impact of MRSA among diabetic healthcare workers requires further research. The high prevalence of MRSA among diabetic foot infections may have implications for antimicrobial resistance, and should encourage strategies aimed at infection prevention or alternative therapies.

Development of predictive nomograms for clinical use to quantify the risk of isolating resistance prone organisms in patients with infected foot ulcers

Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) have been considered prevalent pathogens in foot infections. However, whether empiric therapy directed against these organisms is necessary, and in whom to consider treatment, is rather unclear. The aim of this study was to develop predictive algorithms for forecasting the probability of isolating these organisms in the infected wounds of patients in a population where the prevalence of resistant pathogens is low. This was a retrospective study of regression model-based risk factor analysis that included 140 patients who presented with infected, culture positive foot ulcers to two urban hospitals. A total of 307 bacteria were identified, most frequently MRSA (11.1%). P. aeruginosa prevalence was 6.5%. In the multivariable analysis, amputation (odds ratio (OR) 5.75, 95% confidence interval (CI) 1.48-27.63), renal disease (OR 5.46, 95% CI 1.43-25.16) and gangrene (OR 2.78, 95% CI 0.82-9.59) were identified as risk factors associated with higher while diabetes (OR 0.07, 95% CI 0.01-0.34) and Infectious Diseases Society of America infection severity >3 (OR 0.18, 95% CI 0.03-0.65) were associated with lower odds of P. aeruginosa isolation (C statistic 0.81). Similar analysis for MRSA showed that amputation was associated with significantly lower (OR 0.29, 95% CI 0.09-0.79) risk, while history of MRSA infection (OR 5.63, 95% CI 1.56-20.63) and osteomyelitis (OR 2.523, 95% CI 1.00-6.79) was associated with higher odds of isolation (C statistic 0.69). We developed two predictive nomograms with reasonable to strong ability to discriminate between patients who were likely of being infected with P. aeruginosa or MRSA and those who were not. These analyses confirm the association of some, but also question the significance of other frequently described risk factors in predicting the isolation of these organisms.

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

AIM

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

PATIENTS & METHODS

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

RESULTS

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

CONCLUSION

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

Clinical Utility of Methicillin-Resistant Staphylococcus aureus Nasal Screening for Antimicrobial Stewardship: A Review of Current Literature

Significant clinical and financial consequences are associated with both inadequate and unnecessary exposure to broad-spectrum antibiotics. As such, antimicrobial stewardship programs seek objective, reliable, and cost-effective tests to identify patients at highest or lowest risk for drug-resistant organisms to guide empirical antimicrobial selection. Use of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening to rule out MRSA in lower respiratory tract infections has led to significant reductions in duration of vancomycin therapy. The clinical utility of MRSA nasal screening in other types of infection remains less clear. This review describes the performance of MRSA nasal screening in predicting MRSA infection, highlights practical considerations for use of MRSA nasal screening, and provides guidance for incorporating MRSA nasal screening into clinical practice. With a high negative predictive value when the prevalence of MRSA is low, MRSA nasal screening is a valuable antimicrobial stewardship tool with potential applications beyond lower respiratory tract infections. In appropriately selected patients, negative MRSA nasal screening can prevent initiation or guide discontinuation of anti-MRSA therapy. Antimicrobial stewardship programs should develop institutional guidelines to promote proper use of MRSA nasal screening. Pharmacists are well positioned to assist with education, interpretation, and application of MRSA nasal screening results.

Complications during the treatment of diabetic foot osteomyelitis

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diabetic foot infection: Antibiotic therapy and good practice recommendations

BACKGROUND

Healthcare events related to diabetic foot disease carry a burden of morbidity, mortality and economic cost. Prompt identification of clinical infection with appropriate tissue sampling limits use of broad spectrum empirical antibiotics and improves antibiotic stewardship. Staphylococcus aureus remains the commonest infecting organism and high-dose flucloxacillin remains the empirical antibiotic of choice for antibiotic naïve patients. Barriers to microbe-specific treatment include: adequate tissue sampling, delays in culture results, drug allergies and the emergence of multidrug-resistant organisms which can complicate the choice of targeted antibiotics. Even appropriate antibiotic treatment carries a risk of adverse events including the selection of resistant organisms.

AIMS

Multidisciplinary clinical assessment of a diabetic foot infection is supported by the use of appropriate imaging modalities and deep tissue sampling, both of which are encouraged to enhance sampling accuracy. Narrow-spectrum, high dose, short duration antimicrobial therapy is ideal. Further clarity in these areas would be of benefit to clinicians involved in management of diabetic foot infections.

METHODS

A combination of literature review with expert discussion was used to generate consensus on management of diabetic foot infection, with a specific focus on empirical antimicrobial therapy.

RESULTS

Gram positive organisms represent the commonest pathogens in diabetic foot infection. However there are developing challenges in antimicrobial resistance and antibiotic availability.

DISCUSSION

Recommendations for empirical therapy, including the choice of alternative oral agents and use of outpatient antibiotics would be of benefit to those involved in diabetic foot care.

CONCLUSION

This paper provides advice on empirical antibiotic therapy that may be used as a framework for local guideline development to support clinicians in the management of diabetic foot infection.

The Relationship Between Osteomyelitis Complication and Drug-Resistant Infection Risk in Diabetic Foot Ulcer: A Meta-analysis

In this study, we aimed to investigate the relationship between osteomyelitis complications and drug-resistant infection risk in diabetic foot ulcer. Searches of MEDLINE and ISI databases were performed for the studies. Odds ratios (ORs) for drug-resistant infection incidence were calculated for diabetic foot ulcer patients with or without osteomyelitis complications. Eleven studies (12 cohorts) with 1526 patients were included in this study. Meta-analysis showed that the summary OR was 3.343 (95% CI = 2.355-4.745; Z = 6.75, P < .00001) when compared with osteomyelitis group and without osteomyelitis group. Significant publication bias was found. Sensitivity analysis by only pooled the adjusted ORs showed that the result was robust (the summary OR = 4.081, 95% CI = 2.471-6.739). Subgroup analysis by drug-resistant type showed that the summary OR was 4.391 (95% CI = 2.287-8.394) for methicillin-resistant infection subgroup, and 2.693 (95% CI = 1.882-3.851) for multidrug-resistant infection subgroup. The meta-regression showed that drug-resistant incidence ( t = -0.90, P = .389) and published year ( t = -0.11, P = .913) were not related with the OR changes. In conclusion, our meta-analysis indicates that osteomyelitis complications are related with drug-resistant infection risk in diabetic foot ulcer. We suggest bone culture-based narrow-spectrum antibiotic therapy for osteomyelitis for prevention drug-resistant infection in diabetic foot ulcer.

Diabetic foot infections: Current treatment and delaying the 'post-antibiotic era'

BACKGROUND

Treatment for diabetic foot infections requires properly diagnosing infection, obtaining an appropriate specimen for culture, assessing for any needed surgical procedures and selecting an empiric antibiotic regimen. Therapy will often need to be modified based on results of culture and sensitivity testing. Because of excessive and inappropriate use of antibiotics for treating diabetic foot infections, resistance to the usually employed bacteria has been increasing to alarming levels.

REVIEW

This article reviews recommendations from evidence-based guidelines, informed by results of systematic reviews, on treating diabetic foot infections. Data from the pre-antibiotic era reported rates of mortality of about 9% and of high-level leg amputations of about 70%. Outcomes have greatly improved with appropriate antibiotic therapy. While there are now many oral and parenteral antibiotic agents that have demonstrated efficacy in treating diabetic foot infections, the rate of infection with multidrug-resistant pathogens is growing. This problem requires a multi-focal approach, including providing education to both clinicians and patients, developing robust antimicrobial stewardship programmes and using new diagnostic and therapeutic technologies. Recently, new methods have been developed to find novel antibiotic agents and to resurrect old treatments, like bacteriophages, for treating these difficult infections.

CONCLUSION

Medical and political leaders have recognized the serious global threat posed by the growing problem of antibiotic resistance. By a multipronged approach that includes exerting administrative pressure on clinicians to do the right thing, investing in new technologies and encouraging the profitable development of new antimicrobials, we may be able to stave off the coming 'post-antibiotic era'.

Risk Factors for Invasive Methicillin-Resistant Staphylococcus aureus Infection After Recent Discharge From an Acute-Care Hospitalization, 2011-2013

BACKGROUND

Significant progress has been made in reducing methicillin-resistant Staphylococcus aureus (MRSA) infections among hospitalized patients. However, the decreases in invasive MRSA infections among recently discharged patients have been less substantial. To inform prevention strategies, we assessed risk factors for invasive MRSA infection after acute-care hospitalizations.

METHODS

We conducted a prospective, matched case-control study. A case was defined as MRSA cultured from a normally sterile body site in a patient discharged from a hospital within the prior 12 weeks. Eligible case patients were identified from 15 hospitals across 6 US states. For each case patient, 2 controls were matched for hospital, month of discharge, and age group. Medical record reviews and telephone interviews were performed. Conditional logistic regression was used to identify independent risk factors for postdischarge invasive MRSA.

RESULTS

From 1 February 2011 through 31 March 2013, 194 case patients and 388 matched controls were enrolled. The median time between hospital discharge and positive culture was 23 days (range, 1-83 days). Factors independently associated with postdischarge MRSA infection included MRSA colonization (matched odds ratio [mOR], 7.71; 95% confidence interval [CI], 3.60-16.51), discharge to a nursing home (mOR, 2.65; 95% CI, 1.41-4.99), presence of a chronic wound during the postdischarge period (mOR, 4.41; 95% CI, 2.14-9.09), and discharge with a central venous catheter (mOR, 2.16; 95% CI, 1.13-4.99) or a different invasive device (mOR, 3.03; 95% CI, 1.24-7.39) in place.

CONCLUSIONS

Prevention efforts should target patients with MRSA colonization or those with invasive devices or chronic wounds at hospital discharge. In addition, MRSA prevention efforts in nursing homes are warranted.