Meticillin-resistant Staphylococcus aureus isolated from foot ulcers in diabetic patients in a Chinese care hospital: risk factors for infection and prevalence

Genetic Characterization of Methicillin-Resistant Staphylococcus aureus Isolated From Diabetic Foot Ulcers in a Tertiary Care Hospital in Mysuru, South India

Background Diabetic foot ulcers (DFUs) are common complications in diabetes patients, often leading to sepsis and leg amputation. Methicillin-resistant Staphylococcus aureus (MRSA) infections in DFUs pose challenges due to methicillin resistance with mecA and mecC genes. This study aims to assess the prevalence of MRSA in clinical isolates from DFUs, analyze the antibiogram of MRSA isolates, and detect the presence of the mecA and mecC genes among MRSA isolates. Methodology The isolated S. aureus colonies were identified and antimicrobial susceptibility was performed using the Vitek-2 Compact system. Methicillin resistance was also confirmed through the disc diffusion method. Confirmed methicillin-resistant isolates were subjected to real-time polymerase chain reaction (RT-PCR) to detect mecA and mecC genes. Results A total of 474 purulent samples from DFUs yielded 541 distinct isolates, comprising 201 gram-positive and 340 gram-negative organisms. Among the gram-positive organisms, Staphylococcus species predominated, with 79 S. aureus isolates, 34 of which were methicillin-resistant. All MRSA isolates (100%) were sensitive to tetracycline, linezolid, teicoplanin, and vancomycin, and 94% were sensitive to cotrimoxazole but least susceptible to ciprofloxacin and levofloxacin. RT-PCR confirmed the presence of mecA genes in all 34 isolates and mecC genes in three isolates. Conclusions The presence of mecA in all 34 MRSA isolates underscores consistent methicillin resistance. The co-occurrence of mecA and mecC in three isolates hints at genetic diversity. Two MRSA isolates positive for mecC were isolated from rural patients involved in farming and animal husbandry, suggesting an occupational risk. The third patient was from a non-rural area, indicating potential alternative transmission pathways warranting further investigation.

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.

Distribution of multidrug-resistant bacterial infections in diabetic foot ulcers and risk factors for drug resistance: a retrospective analysis

Objective

To investigate the distribution, drug resistance and risk factors of multi-drug resistant bacterias (MDROs) in patients with Type 2 diabetic foot ulcers (DFU).

Method

The clinical data, foot secretions, pathogenic microorganisms and drug sensitivity tests of 147 patients with type 2 diabetes admitted to our department from January 2018 to December 2021 were analyzed. Patients were divided into two groups according to whether they had been infected with MDROs or not. Seventy-one cases were infected with MDROs as the case group, and the remaining 76 cases were the control group. Chi-square test and t-test were used to analyze the results of MDROs infection and DFU, and logistic multivariate regression was used to evaluate the risk factors of MDROs infection.

Results

A total of 71 strains were isolated from the MDROs-positive group, with the top three being Staphylococcus aureus (46.48%), Escherichia coli (22.53%), and Pseudomonas aeruginosa (18.31%), respectively. Logistic multifactorial regression analysis showed that history of previous antimicrobial exposure, neuroischemic wound, Wagner grade 3-5, and combined osteomyelitis were associated with Type 2 diabetic foot infection MDROs (P < 0.05).

Conclusion

Previous history of antimicrobial exposure, neuroischemic wounds, Wagner grade 3-5, and combined osteomyelitis are independent risk factors for MDROs, which can identify the risk factors for MDROs at an early stage and help to identify people at high risk of MDROs infection and take relevant comprehensive treatment in time to slow down the development of the disease.

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.

The bacteriology of diabetic foot ulcers and infections and incidence of Staphylococcus aureus Small Colony Variants

Introduction. Uninfected diabetes-related foot ulcer (DFU) progression to diabetes-related foot infection (DFI) is a prevalent complication for patients with diabetes. DFI often progresses to osteomyelitis (DFI-OM). Active (growing) Staphylococcus aureus is the most common pathogen in these infections. There is relapse in 40-60 % of cases even when the initial treatment at the DFI stage apparently clears infection.Hypothesis. S. aureus adopts the quasi-dormant Small Colony Variant (SCV) state during DFU and consequently infection, and when present in DFI cases also permits survival in non-diseased tissues as a reservoir to cause relapse.Aim. The aim of this study was to investigate the bacterial factors that facilitate persistent infections.Methodology. People with diabetes were recruited from two tertiary hospitals. Clinical and bacterial data was taken from 153 patients with diabetes (51 from a control group with no ulcer or infection) and samples taken from 102 patients with foot complications to identify bacterial species and their variant colony types, and then compare the bacterial composition in those with uninfected DFU, DFI and those with DFI-OM, of whom samples were taken both from wounds (DFI-OM/W) and bone (DFI-OM/B). Intracellular, extracellular and proximal 'healthy' bone were examined.Results. S. aureus was identified as the most prevalent pathogen in diabetes-related foot pathologies (25 % of all samples). For patients where disease progressed from DFU to DFI-OM, S. aureus was isolated as a diversity of colony types, with increasing numbers of SCVs present. Intracellular (bone) SCVs were found, and even within uninfected bone SCVs were present. Wounds of 24 % of patients with uninfected DFU contained active S. aureus. All patients with a DFI with a wound but not bone infection had previously had S. aureus isolated from an infection (including amputation), representing a relapse.Conclusion. The presence of S. aureus SCVs in recalcitrant pathologies highlights their importance in persistent infections through the colonization of reservoirs, such as bone. The survival of these cells in intracellular bone is an important clinical finding supporting in vitro data. Also, there seems to be a link between the genetics of S. aureus found in deeper infections compared to those only found in DFU.

Clinical and Bacteriological Analyses of Biofilm-Forming Staphylococci Isolated from Diabetic Foot Ulcers

Background

Diabetes mellitus is a chronic disease that is associated with increased morbidity and mortality. Unfortunately, foot ulcers and amputations due to diabetes are very common in developing countries. The purpose of this study was to characterize the clinical presentation of diabetic foot ulcer (DFU) infections, isolate the causative agent, and analyze the biofilm formation and distribution of biofilm-related genes among isolated Staphylococci.

Material and Methods

The study included 100 diabetic patients suffering from DFUs attending Assiut University Hospital. Swabs were collected and antimicrobial susceptibility testing of the isolates was performed. Biofilm formation was tested phenotypically among staphylococcal isolates and the frequency of different biofilm genes was analyzed by PCR. Clinical presentations of diabetic foot ulcers were correlated with bacterial genetic characteristics. Spa types were determined using DNA Gear-a software.

Results

Microbiological analysis showed that 94/100 of the DFUs were positive for bacterial growth. The majority of infections were polymicrobial (54%, n=54/100). Staphylococci were the most commonly detected organisms, of which S. aureus represented 37.5% (n=24/64), S. haemolyticus 23.4% (n=15/64), S. epidermidis 34.3% (n=22/64) and other CNS 4.7% (n=3/64). Interestingly, co-infection with more than one species of Staphylococci was observed in 17.1% (n=11/64) of samples. A high level of antibiotic resistance was observed, where 78.1% (n=50/64) of Staphylococci spp were multidrug-resistant (MDR). Phenotypic detection showed that all isolated Staphylococci were biofilm-formers with different grades. Analysis of biofilm-forming genes among Staphylococci showed that the most predominant genes were icaD, spa, and bap. Isolates with a higher number of biofilm-related genes were associated with strong biofilm formation. Sequencing of the spa gene in S. aureus showed that our isolates represent a collection of 17 different spa types.

Conclusion

The majority of DFUs in our hospital are polymicrobial. Staphylococci other than S.aureus are major contributors to infected DFUs. MDR and biofilm formation are marked among isolates, which is paralleled by the presence of different categories of virulence-related genes. All severely infected wounds were associated with either strong or intermediate biofilm formers. The severity of DFU is directly related to the number of biofilm genes.

Risk factors for wound infection caused by Methicillin Resistant Staphylococcus aureus among hospitalized patients: a case control study from a tertiary care hospital in India

Background

Methicillin Resistant Staphylococcus aureus (MRSA) causes infection in hospitals and communities. The prevalence and risk factors of MRSA infection is not homogenous across the globe.

Objective

To find the risk factors of MRSA infection among hospitalized patients.

Methods

Cross-sectional case control study was conducted at a tertiary care hospital in India. The risk factors were collected using checklist from 130 MRSA and 130 Methicillin sensitive staphylococcus aureus (MSSA) infected patients. The pathogens were isolated from the wound swabs according to Clinical and Laboratory Standards Institute guidelines.

Results

Both the groups were comparable in terms of age, gender, diabetic status, undergoing invasive procedures, urinary catheterization and smoking (p>0.05). Multivariate logistic regression revealed surgical treatment (OR 4.355; CI 1.03, 18.328; p=0.045), prolonged hospitalization (OR 0.307; CI 0.11, 0.832; p=0.020), tracheostomy (OR 5.298, CI 1.16, 24.298; p=0.032), pressure/venous ulcer (OR 7.205; CI 1.75, 29.606; p=0.006) and previous hospitalization (OR 2.883; CI 1.25, 6.631; p=0.013) as significant risk factors for MRSA infection.

Conclusion

Surgical treatment, prolonged and history of hospitalization, having tracheostomy for ventilation and pressure/venous ulcer were the key risk factors. Therefore, special attention has to be given to the preventable risk factors while caring for hospitalized patients to prevent MRSA infection.

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.

Antimicrobial Susceptibility Testing and Phenotypic Detection of MRSA Isolated from Diabetic Foot Infection

Background

Diabetic foot infection (DFI) is a common and costly complication of diabetes that may be caused by various bacteria with multi-resistant genes. The aim of this study is to evaluate the efficacy of phenotypic methods for identification of methicillin-resistant Staphylococcus aureus (MRSA) with genotypic detection of MRSA-related genes.

Methods

In this cross-sectional study, swab samples were collected from patients with DFI from hospitals in Sulaimani/Iraq in April–July 2019. All the samples were processed for microbiological assessment and further MRSA phenotypic and genotypic testing.

Results

A total of 46 swab samples were collected from diabetic foot ulcers of 29 males and 17 females. Most samples (93.5%) showed positive growth, with higher proportions of monomicrobial (23; 53.5%) than mixed-bacterial infections (20; 46.5%) and S. aureus as the predominant pathogen. Conventional methods of MRSA detection, such as cefoxitin disc diffusion, can predict methicillin resistance in 45.8% of the cases. Real-time/conventional PCR showed that 41.6% of Staphylococcus aureus were positive for the mecA gene, while none of the isolates was positive for PVL.

Conclusion

Staphylococcus aureus was the predominant pathogen in DFI. Although cefoxitin and oxacillin disc diffusion methods can help in the prediction of MRSA, real-time PCR is a reliable method for MRSA detection and confirmation.

Bacterial ecology and antibiotic resistance mechanisms of isolated resistant strains from diabetic foot infections in the north west of Algeria

BACKGROUND

In front of the polymorphic bacterial ecology and antibiotic resistance in diabetic patients with foot infections and good patient care, collaboration between clinicians and microbiologists is needed to improve assessment and management of patients with this pathology.

OBJECTIVE

This study was designed to characterize the bacterial ecology of diabetic foot infection (DFIs) and to determine the different mechanisms of resistance involved.

METHODS

In this study bacterial strains and antibiotic resistance profiles were determined from diabetic foot infections patients (n = 117). The identification of resistance mechanisms, such as penicillinase and/or extended-spectrum β-lactamase production (ESBL), methicillin-resistant Staphylococcus aureus (MRSA) and efflux pump over-expression were performed.

RESULTS

A high prevalence of Gram-negative bacteria (61%) with Escherichia coli, and other Enterobacteriaceae and Pseudomonas aeruginosa being the predominant isolates. Gram positive bacteria mainly represented by Staphylococcus aureus accounted for 39% of the isolates. 93.5% of the Enterobacteriaceae were resistant to, at least, one molecule in the β-lactam family, while the majority of the Staphylococci were resistant to penicillin G and tetracycline (93.3% and 71.7%). The majority of non-fermenting Gram negative bacteria were also resistant to fluoroquinolones. β-lactamase detection tests revealed the presence of extended-spectrum β-lactamase in 43.5% of the Enterobacteriaceae, while methicillin-resistant Staphylococcus aureus represented 18.2% of the isolates. Additionally, 50.9% of non-fermenting Gram negative bacteria were overproducing efflux pumps.

CONCLUSION

All Acinetobacter Baumannii were Multidrug-Resistant (MDR), as the majority of Staphylococci, and Enterobacteriaceae. These results should be taken into account by the clinician in the prescription of probabilistic antibiotic therapy in this context.

Evolutionary trends in bacteria isolated from moderate and severe diabetic foot infections in a Portuguese tertiary center

INTRODUCTION

Diabetic Foot infections (DFI) are a major cause of hospitalization in patients with diabetes. The microbiological study of diabetic ulcers is essential to adequate antibiotic therapy and to minimize the selection of resistant microorganisms. The aim of this study was to characterize and to compare the evolution of isolated microorganisms between the biennium 2010-2011 and 2016-2017, in hospitalized patients with DFI.

MATERIAL AND METHODS

Retrospective evaluation of the clinical and analytical data of patients who were admitted due to DFI in 2010-2011 (group 2010/11) and 2016-2017 (group 2016/17). Only the first hospitalization for each patient was included. An adequate descriptive and comparative statistical analysis was performed.

RESULTS

There were 274 admissions due to DFI, 151 in 2010/11 and 123 in 2016/17. There was an increase in admissions due to neuroischemic DFI (51.0% in 2010/11 to 61.8% in 2016/17, p = 0.048). Staphylococcus aureus (SA) was the most common isolate in 2010/11 (26.7%). In 2016/17 most cultures were mixed polymicrobial and isolation of Enterobacteriaceae and Pseudomonas aeruginosa increased from 2010/11 to 2016/17 (15.9% to 30.6%, p = 0.001, and 9.1% to 13.7%, p = 0.048, respectively).

CONCLUSION

There was an increase in the prevalence of neuroischemic DFU. The Enterobacteriaceae family replaced SA as the most prevalent pathogen in DFI, with an increase in the isolation of gram-negative microorganisms and mixed polymicrobial cultures. Chronic neuroischemic infected ulcers usually present distinct bacterial isolates; knowledge about the most common agents is warranted in order to better select empiric antibiotic therapy.

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.

Antibacterial Activity of Honey against Methicillin-Resistant Staphylococcus aureus: A Laboratory-Based Experimental Study

Background

Antimicrobial drug resistance is one of the serious issues this world is facing nowadays, and increased cost of searching for effective antimicrobial agents and the decreased rate of new drug discovery have made the situation increasingly worrisome.

Objective

The aim of this study is to determine in vitro antibacterial activity of honey against methicillin-resistant Staphylococcus aureus isolates from wound infection.

Methods

An experimental study was conducted from May to November 2017. Methicillin resistance was detected using cefoxitin (30 μg) and oxacillin (1 μg) antibiotic discs. Different concentrations of honey (25–100% v/v) were tested against each type of clinical isolates obtained from wound infection. A preliminary sensitivity test was done to all types of honey by using disk diffusion while minimum inhibitory concentration and minimum bactericidal concentration were determined for the most potent honey by the broth dilution technique. All statistical analysis was performed by using Statistical Package for the Social Sciences version 20.

Results

In this study, 36 bacterial isolates were recovered from 50 specimens, showing an isolation rate of 72%. The predominant bacteria isolated from the infected wounds were Staphylococcus aureus (15, 41.7%). Among identified Staphylococcus aureus, methicillin resistance accounts for 10 isolates (27.8%). All isolates showed a high frequency of resistance to tetracycline. Four collected honey varieties exhibited antibacterial activity, while the strongest inhibitory activity was demonstrated by honey-2 at 75% v/v. The mean MIC and MBC of honey-2 ranged from 9.38 to 37.5% v/v.

Conclusions

Tested honey has both a bacteriostatic and bactericidal activity. Among the tested honey, “honey-2” had high antibacterial potency than others.

Methicillin- and Inducible Clindamycin-Resistant Staphylococcus aureus among Patients with Wound Infection Attending Arba Minch Hospital, South Ethiopia

Background

Wound infection is one of the most common hospital-acquired infections. Different bacteria cause infection, of which Staphylococcus aureus is one of the known bacteria in causing infection with increased drug-resistant isolates.

Objective

To assess the prevalence and antimicrobial susceptibility pattern of methicillin and inducible clindamycin-resistant Staphylococcus aureus among patients with wound infections attending Arba Minch Hospital.

Methods

A facility-based cross-sectional study was conducted from April to June 2017. A pretested questionnaire was used to collect demographic data and clinical characteristics. Wound swabs were cultured and identified by standard techniques. Antibiotic susceptibility tests were performed by the Kirby–Bauer disc diffusion method. Methicillin resistance was detected using the cefoxitin (30 μg) antibiotic disc while inducible clindamycin resistance was detected by the D-zone test. The data were analyzed using Statistical Package for Social Science, version 20. p value <0.05 was considered statistically significant.

Results

A total of 161 patients were enrolled and a majority of them were female (90, 50.9%). Among the collected samples, 79 (49.7%) were positive for S. aureus; of this, methicillin resistance accounted for 65 (82.3%). Out of 22 (27.8%) erythromycin-resistant isolates, 19 (24.1%) showed inducible clindamycin resistance. Methicillin-resistant S. aureus showed higher resistance against tetracycline (72.3%) followed by cotrimoxazole (43.1%) and 100% sensitivity to vancomycin. The overall prevalence of inducible clindamycin resistance among methicillin-resistant isolates was 16 (24.6%).

Conclusion

The increasing prevalence of methicillin-resistant S. aureus and the coresistance against other therapeutic options like clindamycin is becoming an obstacle in the treatment of infections which need attention from concerned bodies.

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.

Blue Laser Inhibits Bacterial Growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa

OBJECTIVE

The purpose of this study was to analyze the influence of blue laser on bacterial growth of the main species that usually colonize cutaneous ulcers, as well as its effect over time following irradiation.

BACKGROUND DATA

The use of blue laser has been described as an adjuvant therapeutic method to inhibit bacterial growth, but there is no consensus about the best parameters to be used.

METHODS

Strains of Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922 were suspended in saline solution at a concentration of 1.5×10(3) colony forming units (CFU)/mL. Next, 300 μL of this suspension was transferred to a microtitulation plate and exposed to a single blue laser irradiation (450 nm) at fluences of 0 (control), 3, 6, 12, 18, and 24 J/cm(2). Each suspension was spread over the surface of a Petri plate before being incubated at 37°C, and counts of CFU were determined after 24 and 48 h.

RESULTS

Blue laser inhibited the growth of S. aureus and P. aeruginosa at fluences >6 J/cm(2). On the other hand, E. coli was inhibited at all fluences tested, except at 24 J/cm(2).

CONCLUSIONS

Blue laser light was capable of inhibiting bacterial growth at low fluences over time, thus presenting no time-dependent effect.

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

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

Combination of therapeutic ultrasound with antibiotics interfere with the growth of bacterial culture that colonizes skin ulcers: An in-vitro study

Staphylococcus aureus and Escherichia coli are among the major bacterial species that colonize skin ulcers. Therapeutic ultrasound (TUS) produces biophysical effects that are relevant to wound healing; however, its application over a contaminated injury is not evidence-based. The objective of this research was to analyze the effect of TUS on in vitro-isolated S. aureus and E. coli, including the combination of ultrasound and antibiotics, in order to assess their antibiotic action on bacterial susceptibility. For the experiments, the bacterial strains were suspended in saline, then diluted (10(4)CFU/mL) for irradiation (at 1 and 3MHz, 0.5 and 0.8W/cm(2) for 0 and 15min) and the combination treatment of ultrasonication and antibiotics was administered by adding nalidixic acid (S. aureus) and tetracycline (E. coli) at concentrations equivalent to 50% of the minimum inhibitory concentration (MIC). The experiments were carried out in duplicate with six repetitions. The suspensions were inoculated on to Petri plates and incubated at 37°C and the colony forming units (CFUs) were counted after 24h. The results were subjected to the Shapiro-Wilk normality test, followed by parametric ANOVA and Tukey's post hoc test at a significance level of 1%. The results demonstrated that the action of TUS at 1MHz inhibited bacterial growth while at 3MHz, bacterial growth was observed in both species. However, the synergistic combination of ultrasound and antibiotics was able to inhibit the growth of both bacteria completely after 15min of ultrasonication. The results suggest that the action of ultrasound on S. aureus and E. coli are dependent on the oscillation frequency as well as the intensity and time of application. The combination of ultrasound with antibiotics was able to inhibit bacterial growth fully at all frequencies and doses in both species.

Staphylococcus aureus Toxins and Diabetic Foot Ulcers: Role in Pathogenesis and Interest in Diagnosis

Infection of foot ulcers is a common, often severe and costly complication in diabetes. Diabetic foot infections (DFI) are mainly polymicrobial, and Staphylococcus aureus is the most frequent pathogen isolated. The numerous virulence factors and toxins produced by S. aureus during an infection are well characterized. However, some particular features could be observed in DFI. The aim of this review is to describe the role of S. aureus in DFI and the implication of its toxins in the establishment of the infection. Studies on this issue have helped to distinguish two S. aureus populations in DFI: toxinogenic S. aureus strains (harboring exfoliatin-, EDIN-, PVL- or TSST-encoding genes) and non-toxinogenic strains. Toxinogenic strains are often present in infections with a more severe grade and systemic impact, whereas non-toxinogenic strains seem to remain localized in deep structures and bone involving diabetic foot osteomyelitis. Testing the virulence profile of bacteria seems to be a promising way to predict the behavior of S. aureus in the chronic wounds.

Aerobic bacterial profile and antibiotic resistance in patients with diabetic foot infections

INTRODUCTION

This study aimed to determine the frequencies of bacterial isolates cultured from diabetic foot infections and assess their resistance and susceptibility to commonly used antibiotics.

METHODS

This prospective study included 41 patients with diabetic foot lesions. Bacteria were isolated from foot lesions, and their antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method and/or broth method [minimum inhibitory concentration (MIC)].

RESULTS

The most common location of ulceration was the toe (54%), followed by the plantar surface (27%) and dorsal portion (19%). A total of 89 bacterial isolates were obtained from 30 patients. The infections were predominantly due to Gram-positive bacteria and polymicrobial bacteremia. The most commonly isolated Gram-positive bacteria were Staphylococcus aureus, followed by Staphylococcus saprophyticus, Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus pneumoniae. The most commonly isolated Gram-negative bacteria were Proteus spp. and Enterobacterspp., followed by Escherichia coli, Pseudomonasspp., and Citrobacterspp. Nine cases of methicillin-resistant Staphylococcus aureus (MRSA) had cefoxitin resistance, and among these MRSA isolates, 3 were resistant to vancomycin with the MIC technique. The antibiotic imipenem was the most effective against both Gram-positive and Gram-negative bacteria, and gentamicin was effective against Gram-negative bacteria.

CONCLUSIONS

The present study confirmed the high prevalence of multidrug-resistant pathogens in diabetic foot ulcers. It is necessary to evaluate the different microorganisms infecting the wound and to know the antibiotic susceptibility patterns of the isolates from the infected wound. This knowledge is crucial for planning treatment with the appropriate antibiotics, reducing resistance patterns, and minimizing healthcare costs.

Ertapenem versus piperacillin/tazobactam for diabetic foot infections in China: a Phase 3, multicentre, randomized, double-blind, active-controlled, non-inferiority trial

OBJECTIVES

Few randomized controlled studies have compared antibiotic regimens against diabetic foot infections (DFIs) in Chinese patients. We evaluated the efficacy and safety of ertapenem versus piperacillin/tazobactam for the treatment of DFIs in Chinese patients.

METHODS

Patients with moderate to severe DFIs requiring parenteral antibiotics were randomized in a 1 : 1 ratio to receive ertapenem (1.0 g once daily) or piperacillin/tazobactam (4.5 g every 8 h) by 30 min intravenous (iv) infusions for ≥5 days. The primary outcome was favourable clinical response at discontinuation of iv therapy (DCIV). An evaluable-patient population was identified for primary analysis of non-inferiority at -15%. Safety was assessed. ClinicalTrials.gov: NCT01370616.

RESULTS

Of 565 patients randomized, 443 patients (ertapenem = 219 and piperacillin/tazobactam = 224) were clinically evaluable for primary analysis. In the clinically evaluable population, the proportions of patients with favourable clinical response at DCIV were 93.6% (205/219) and 97.3% (218/224) in the ertapenem and piperacillin/tazobactam groups, respectively (difference: -3.8%, 95% CI: -8.3%, 0.0%). Ertapenem had a significantly lower favourable clinical response rate (91.5% versus 97.2%, 95% CI for difference: -12.1%, -0.3%) at DCIV in severe DFI patients. In the modified ITT population, 88.8% (237/267) and 90.6% (241/266) of patients in the ertapenem and piperacillin/tazobactam groups, respectively, had favourable clinical responses at DCIV (difference: -1.9%, 95% CI: -7.3%, 3.3%). Microbiological eradications of causative pathogens and adverse events were similar between treatment groups.

CONCLUSIONS

Treatment with ertapenem was non-inferior to piperacillin/tazobactam in Chinese patients with DFIs. Ertapenem treatment resulted in a markedly lower rate of clinical resolution in severe DFIs.

Do Diabetic Foot Infections With Methicillin-Resistant Staphylococcus aureus Differ From Those With Other Pathogens?

There is controversy as to whether or not diabetic foot infections (DFIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with worse outcomes than DFIs caused by other pathogens. To address this issue we performed a nonsystematic literature search of published articles in English language journals seeking studies reporting on the outcomes of DFIs related to their microbiology. We retrieved 48 articles published from 1999 to 2013 that described a total of 7771 cases of DFI. The overall proportion of DFIs with an isolate of S aureus was about 30%; just over one third of these (11% of all cases) were MRSA strains. Among the DFI cases caused by MRSA 1543 were episodes of soft tissue infections and 113 of osteomyelitis, while non-MRSA organisms caused 5761 soft tissue infections and 354 cases of osteomyelitis. Only 5 of the included articles attempted a comparison between DFI caused by MRSA and those caused by other pathogens, with no clear differences noted. The median total duration of antibiotic therapy for DFI caused by MRSA was 26 days, of which a median of 10 days was given intravenously. Only a few articles reported the proportion of patients with a recurrence, but they often did not differentiate between MRSA and non-MRSA cases. Four publications reported a worse functional or microbiological outcome in MRSA, compared to non-MRSA, cases, but the findings were variable and differences did not seem to be significant. Many trials failed to adjust for case-mix or to definitively demonstrate a relationship between microbiology and outcomes. Few of the articles specifically commented on whether the MRSA isolates were health care- or community-acquired strains. Notwithstanding the substantial limitations of the available literature, there does not appear to be a need for any special treatment for DFI caused by MRSA. The current guidelines for treating according to established international recommendations seem appropriate.

Characteristics of microbial drug resistance and its correlates in chronic diabetic foot ulcer infections

While virulence factors and the biofilm-forming capabilities of microbes are the key regulators of the wound healing process, the host immune response may also contribute in the events following wound closure or exacerbation of non-closure. We examined samples from diabetic and non-diabetic foot ulcers/wounds for microbial association and tested the microbes for their antibiotic susceptibility and ability to produce biofilms. A total of 1074 bacterial strains were obtained with staphylococci, Pseudomonas, Citrobacter and enterococci as major colonizers in diabetic samples. Though non-diabetic samples had a similar assemblage, the frequency of occurrence of different groups of bacteria was different. Gram-negative bacteria were found to be more prevalent in the diabetic wound environment while Gram-positive bacteria were predominant in non-diabetic ulcers. A higher frequency of monomicrobial infection was observed in samples from non-diabetic individuals when compared to samples from diabetic patients. The prevalence of different groups of bacteria varied when the samples were stratified according to age and sex of the individuals. Several multidrug-resistant strains were observed among the samples tested and most of these strains produced moderate to high levels of biofilms. The weakened immune response in diabetic individuals and synergism among pathogenic micro-organisms may be the critical factors that determine the delicate balance of the wound healing process.

Antibiogram of Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus in patients with diabetes

Objective: To determine the antibiogram of Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus (MRSA) in patients with diabetes.

Methods: The study was carried out in the Microbiology Department of Clinical and Research Laboratory, Baqai Institute of Diabetology and Endocrinology (BIDE) from January 2012 to December 2012. All samples received in the laboratory were processed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Identification of Pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus (MRSA) was done and antimicrobial susceptibility pattern was determined by disc diffusion method.

Results: A total of 585 pathogens were isolated from 542 specimens of patients with diabetes. One hundred twenty one (20.68%) Pseudomonas aeruginosa and 25(4.27%) non-aeruginosa Pseudomonas were detected from 542 samples. Among 108 (18%) samples detecting the growth of Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA) were found in 42 (39%) samples. Pseudomonas aeruginosa showed marked susceptibility to imipenem (100%) followed by piperacillin / tazobactam (90.91%). All MRSA positive specimens were susceptible to vancomycin, but highly or completely resistant to the other antimicrobial drugs.

Conclusion: In the present study imipenem, piperacillin/tazobactam and sulbactam-cefoperazone were found to be the most effective drugs against Pseudomonas aeruginosa. The majority of MRSA were resistant to one or more than one antimicrobial drugs. Vancomycin and imipenem were the most effective drugsagainstStaphylococcus aureus and MRSA. .

Daptomycin for methicillin-resistant Staphylococcus aureus diabetic foot infections

BACKGROUND

Diabetic foot infection (DFI) is a serious, difficult-to-treat infection, especially when caused by methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin has been the standard treatment for MRSA infection, but lower response rates in MRSA skin infections have been reported. This analysis assessed the outcome and safety of daptomycin therapy in patients with a DFI caused by MRSA.

METHODS

Using the Cubicin Outcomes Registry and Experience and the European Cubicin Outcomes Registry and Experience (2006-2009), 79 patients with MRSA DFI were identified and included in this analysis.

RESULTS

In the 74 evaluable patients, daptomycin was administered at a median dose of 4.8 mg/kg primarily every 24 hours (85.1%) and for a median of 15.0 days. Overall, 77.0% of the patients (57 of 74) received initial therapy with activity against MRSA; however, of patients receiving daptomycin as second-line therapy (n = 31), only 45.2% were treated with an antibiotic agent active against MRSA. The overall clinical success and treatment failure rates were 89.2% and 10.8%, respectively. Success with daptomycin therapy was higher in patients who had surgery and in those whose initial therapy was daptomycin. Eleven patients had 14 adverse events, two of which were possibly related to daptomycin use and led to discontinuation.

CONCLUSIONS

In a large real-world cohort of patients with MRSA DFI, daptomycin therapy was shown to be generally well tolerated and effective. The use of an anti-MRSA antibiotic agent should be considered when implementing first-line antibiotic drug therapy for DFI in countries where MRSA is common to avoid inappropriate empirical treatment and potential negative effects on outcomes.

Diversity of methicillin-resistant Staphylococcus aureus strains isolated from residents of 26 nursing homes in Orange County, California

Nursing homes represent a unique and important methicillin-resistant Staphylococcus aureus (MRSA) reservoir. Not only are strains imported from hospitals and the community, strains can be transported back into these settings from nursing homes. Since MRSA bacteria are prevalent in nursing homes and yet relatively poorly studied in this setting, a multicenter, regional assessment of the frequency and diversity of MRSA in the nursing home reservoir was carried out and compared to that of the MRSA from hospitals in the same region. The prospective study collected MRSA from nasal swabbing of residents of 26 nursing homes in Orange County, California, and characterized each isolate by spa typing. A total of 837 MRSA isolates were collected from the nursing homes. Estimates of admission prevalence and point prevalence of MRSA were 16% and 26%, respectively. The spa type genetic diversity was heterogeneous between nursing homes and significantly higher overall (77%) than the diversity in Orange County hospitals (72%). MRSA burden in nursing homes appears largely due to importation from hospitals. As seen in Orange County hospitals, USA300 (sequence type 8 [ST8]/t008), USA100 (ST5/t002), and a USA100 variant (ST5/t242) were the dominant MRSA clones in Orange County nursing homes, representing 83% of all isolates, although the USA100 variant was predominant in nursing homes, whereas USA300 was predominant in hospitals. Control strategies tailored to the complex problem of MRSA transmission and infection in nursing homes are needed in order to minimize the impact of this unique reservoir on the overall regional MRSA burden.

National surveillance of methicillin-resistant Staphylococcus aureus in China highlights a still-evolving epidemiology with 15 novel emerging multilocus sequence types

The global spread of methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem, particularly in mainland China. In order to better understand the national molecular epidemiology and resistance profiles of hospital-associated MRSA (HA-MRSA) in China, a laboratory-based multicenter surveillance study was conducted. Sixty-nine hospitals in 45 large cities in 27 provinces were involved, and a total of 1,141 HA-MRSA isolates were collected during the 6-month study period in 2011. All MRSA isolates were characterized by multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, spa typing, detection of the Panton-Valentine leukocidin (PVL) locus (lukS-PV and lukF-PV), and antibiogram analysis. ST239-III-t030, ST239-III-t037, and ST5-II-t002 were the predominant HA-MRSA clones (overall prevalence rates, 57.1%, 12.9%, and 8.1%, respectively), although the prevalence rates of these major clones varied markedly in different administrative regions. Of note, 6.6% of the HA-MRSA isolates were found to belong to ST59, which had typical community-associated MRSA (CA-MRSA) features, including carriage of SCCmec type IV or V and PVL and less antimicrobial resistance than other major HA-MRSA clones. Moreover, among 36 MLST sequence types (STs) identified, 15 STs, accounting for 3.5% of total isolates, were novel. A novel ST designated ST2590, which is a single-locus variant of ST5-II-t002, was identified in three hospitals in two large cities, with a total of 17 isolates. To further monitor trends in HA-MRSA prevalence, epidemic clonal shifts, clone emergence, and transmission between community and health care settings, longitudinal national MRSA surveillance is required.

Molecular epidemiology of Staphylococcus aureus strains isolated from inpatients with infected diabetic foot ulcers in an Algerian University Hospital

Staphylococcus aureus is the most common pathogen cultured from diabetic foot infection (DFI). The consequence of its spread to soft tissue and bony structures is a major causal factor for lower-limb amputation. The objective of the study was to explore ecological data and epidemiological characteristics of S. aureus strains isolated from DFI in an Algerian hospital setting. Patients were included if they were admitted for DFI in the Department of Diabetology at the Annaba University Hospital from April 2011 to March 2012. Ulcers were classified according to the Infectious Diseases Society of America/International Working Group on the Diabetic Foot classification system. All S. aureus isolates were analysed. Using oligonucleotide arrays, S. aureus resistance and virulence genes were determined and each isolate was affiliated to a clonal complex. Among the 128 patients, 277 strains were isolated from 183 samples (1.51 isolate per sample). Aerobic Gram-negative bacilli were the most common isolated organisms (54.9% of all isolates). The study of ecological data highlighted the extremely high rate of multidrug-resistant organisms (MDROs) (58.5% of all isolates). The situation was especially striking for S. aureus [(85.9% were methicillin-resistant S. aureus (MRSA)], Klebsiella pneumonia (83.8%) and Escherichia coli (60%). Among the S. aureus isolates, 82.2% of MRSA belonged to ST239, one of the most worldwide disseminated clones. Ten strains (13.7%) belonged to the European clone PVL+ ST80. ermA, aacA-aphD, aphA, tetM, fosB, sek, seq, lukDE, fnbB, cap8 and agr group 1 genes were significantly associated with MRSA strains (p <0.01). The study shows for the first time the alarming prevalence of MDROs in DFI in Algeria.

2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections

Foot infections are a common and serious problem in persons with diabetes. Diabetic foot infections (DFIs) typically begin in a wound, most often a neuropathic ulceration. While all wounds are colonized with microorganisms, the presence of infection is defined by ≥2 classic findings of inflammation or purulence. Infections are then classified into mild (superficial and limited in size and depth), moderate (deeper or more extensive), or severe (accompanied by systemic signs or metabolic perturbations). This classification system, along with a vascular assessment, helps determine which patients should be hospitalized, which may require special imaging procedures or surgical interventions, and which will require amputation. Most DFIs are polymicrobial, with aerobic gram-positive cocci (GPC), and especially staphylococci, the most common causative organisms. Aerobic gram-negative bacilli are frequently copathogens in infections that are chronic or follow antibiotic treatment, and obligate anaerobes may be copathogens in ischemic or necrotic wounds. Wounds without evidence of soft tissue or bone infection do not require antibiotic therapy. For infected wounds, obtain a post-debridement specimen (preferably of tissue) for aerobic and anaerobic culture. Empiric antibiotic therapy can be narrowly targeted at GPC in many acutely infected patients, but those at risk for infection with antibiotic-resistant organisms or with chronic, previously treated, or severe infections usually require broader spectrum regimens. Imaging is helpful in most DFIs; plain radiographs may be sufficient, but magnetic resonance imaging is far more sensitive and specific. Osteomyelitis occurs in many diabetic patients with a foot wound and can be difficult to diagnose (optimally defined by bone culture and histology) and treat (often requiring surgical debridement or resection, and/or prolonged antibiotic therapy). Most DFIs require some surgical intervention, ranging from minor (debridement) to major (resection, amputation). Wounds must also be properly dressed and off-loaded of pressure, and patients need regular follow-up. An ischemic foot may require revascularization, and some nonresponding patients may benefit from selected adjunctive measures. Employing multidisciplinary foot teams improves outcomes. Clinicians and healthcare organizations should attempt to monitor, and thereby improve, their outcomes and processes in caring for DFIs.