Clinical and bacteriological survey of diabetic foot infections in Lisbon

Molecular characterization of Pseudomonas aeruginosa from diabetic foot infections in Tunisia

Background. Pseudomonas aeruginosa is an invasive organism that frequently causes severe tissue damage in diabetic foot ulcers.Gap statement. The characterisation of P. aeruginosa strains isolated from diabetic foot infections has not been carried out in Tunisia.Purpose. The aim was to determine the prevalence of P. aeruginosa isolated from patients with diabetic foot infections (DFIs) in Tunisia and to characterize their resistance, virulence and molecular typing.Methods. Patients with DFIs admitted to the diabetes department of the International Hospital Centre of Tunisia, from September 2019 to April 2021, were included in this prospective study. P. aeruginosa were obtained from the wound swabs, aspiration and soft tissue biopsies during routine clinical care and were confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing, serotyping, integron and OprD characterization, virulence, biofilm production, pigment quantification, elastase activity and molecular typing were analysed in all recovered P. aeruginosa isolates by phenotypic tests, specific PCRs, sequencing, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing.Results. Sixteen P. aeruginosa isolates (16.3 %) were recovered from 98 samples of 78 diabetic patients and were classified into 6 serotypes (O:11 the most frequent), 11 different PFGE patterns and 10 sequence types (three of them new ones). The high-risk clone ST235 was found in two isolates. The highest resistance percentages were observed to netilmicin (69 %) and cefepime (43.8 %). Four multidrug-resistant (MDR) isolates (25 %) were detected, three of them being carbapenem-resistant. The ST235-MDR strain harboured the In51 class 1 integron (intI1 +aadA6+orfD+qacED1-sul1). According to the detection of 14 genes involved in virulence or quorum sensing, 5 virulotypes were observed, including 5 exoU-positive, 9 exoS-positive and 2 exoU/exoS-positive strains. The lasR gene was truncated by ISPpu21 insertion sequence in one isolate, and a deletion of 64 bp in the rhlR gene was detected in the ST235-MDR strain. Low biofilm, pyoverdine and elastase production were detected in all P. aeruginosa; however, the lasR-truncated strain showed a chronic infection phenotype characterized by loss of serotype-specific antigenicity, high production of phenazines and high biofilm formation.Conclusions. Our study demonstrated for the first time the prevalence and the molecular characterization of P. aeruginosa strains from DFIs in Tunisia, showing a high genetic diversity, moderate antimicrobial resistance, but a high number of virulence-related traits, highlighting their pathological importance.

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

Introduction

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

Methods

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

Results

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

Discussion

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

Systematic review registration

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

Microbiological Species and Antibiotic Resistance in Diabetic and Nondiabetic Lower Extremity Wounds: A Comparative Cross-Sectional Study

Severe lower extremity wounds have an increased risk of complications and limb loss. The aim of this study was to evaluate and compare the microbiological profile and antibiotic resistance of wounds in diabetic and nondiabetic patients. A cross-sectional comparative study was carried out at a public hospital including 111 patients with moderate to severe wound infections. Tissue samples were collected during a surgical procedure. One hundred and four patients (94%) had positive cultures and 88 (79%) had a Gram-negative microorganism. Among the 185 cultured microorganisms, 133 (72%) were Gram-negative species. Pseudomonas aeruginosa (23 cases) was the most isolated Gram-negative species, and Enterococcus faecalis (26 cases) was the most prevalent Gram-positive species. Among 185 isolated species, 45 (24%) were extended-spectrum beta-lactamase producers, 23 (12%) were carbapenem-resistant, and 5 (3%) were methicillin-resistant Staphylococcus aureus. Findings revealed that there was no significant difference in the microbiological profile and antibiotic resistance among patients with lower extremity wounds whether they were diabetic or nondiabetic.

Clinical and Microbiological Profile of Diabetic Foot Ulcers Infected With Staphylococcus aureus in a Regional General Hospital in Bahia, Brazil

It is necessary to know the resistance profile of Staphylococcus aureus to better control diabetic foot ulcer infections, to establish rational antibiotic therapy, and to avoid the development of resistant strains. This cross-sectional study evaluated the clinical parameters, virulence, and antimicrobial resistance profiles of S aureus in patients with diabetic foot disease admitted to a public hospital. S aureus strains were identified in patients with diabetes with amputation indication. Infected tissue samples were collected, microbes were isolated and identified. The microbial resistance profile was determined. Samples were also analyzed for biofilm formation and other virulence markers. The 34 individuals examined were mostly men, black, aged 60 years on average, and generally had a low income and education level. Most individuals had type 2 diabetes, and the mean time since diagnosis was 13.9 years. On an SF-36 (the Medical Outcomes Study 36-item short-form health survey) quality-of-life questionnaire, 75% of individuals obtained a score equal to 0 for physical impairment. S aureus specimens from 17 patients were isolated, corresponding to 50% of samples. Five isolates were classified as methicillin-resistant S aureus (MRSA). Molecular typing revealed that 20% of MRSA strains were SCCmec type V and 80% were type I. All isolates were sensitive to doxycycline; 61.5% were resistant to erythromycin, 38.5% to cefoxitin, 30.7% to clindamycin and ciprofloxacin, 23% to meropenem, 15.3% to gentamicin, 38.5% to oxacillin, and 7.7% (one strain) to vancomycin. Regarding biofilm production, 53% of samples were able to produce biofilms, and 84.6% had icaA and/or icaD genes. Additionally, the following enterotoxin genes were identified in the isolates: seb, sec, seg, and sei (5.9%, 5.9%, 11.8%, and 23.9%, respectively) and agr types 1 (5.9%) and 2 (11.8%). Genotypic evaluation made it possible to understand the pathogenicity of S aureus strains isolated from the diabetic foot; laboratory tests can assist in the monitoring of patients with systemic involvement.

Investigating wound healing potential of sesamol loaded solid lipid nanoparticles: Ex-vivo, in vitro and in-vivo proof of concept

Sesamol, a lignan, obtained from sesame seeds (Sesamum indicum Linn., Pedaliaciae) has a promising antioxidant, and anti-inflammatory profile. When applied topically, free sesamol rapidly crosses skin layers and gets absorbed in systemic circulation. Its encapsulation into solid lipid nanoparticles not only improved its localised delivery to skin but also resulted in better skin retention, as found in ex-vivo skin retention studies. Free and encapsulated sesamol was compared for antimicrobial and antibiofilm activity against some common skin pathogens and it was found that encapsulation improved the antimicrobial profile by 200%. In vivo evaluation in diabetic open excision wound model suggested that encapsulation of sesamol in SLNs substantially enhanced its wound healing potential when investigated for biophysical, biochemical and histological parameters. It was envisaged that this was achieved via inhibiting bacterial growth and clearing the bacterial biofilm at the wound site, and by regulating oxidative stress in skin tissue.

Commonly associated aerobic microbial pathogens and their antibiotic susceptibility profile in diabetic foot ulcers in tertiary care centre in Western Maharashtra

PURPOSE

Diabetes mellitus (DM-II) is a metabolic disorder either due to reduced insulin production or reduced insulin sensitivity. Diabetic foot ulcer (DFU) is one of the most devastating complications of DM-II. This study was performed to assess commonly isolated micro-organisms and their anti-microbial sensitivity pattern in diabetic foot ulcers in a tertiary care centre in Western Maharashtra.

METHODS

Adult patients with a known case of DM-II with foot lesions, suspected to be a Diabetic Foot Infections (DFIs) at the tertiary care hospital from Aug 2022 to Sept 2022 were included in the study. After obtaining informed written consent, pus sample was collected with sterile swab from lesion's base and submitted to Microbiology Laboratory for aerobic culture and sensitivity.

RESULTS

Out of 56 enrolled patients, 47 (83.9%) patients tested positive for bacteriological growth and there was 'no growth' in 9 (16.07%) patients at the end of 48 h of aerobic incubation. There was male preponderance and patients were in age group of 35-85 years. The most commonly isolated micro-organisms were P. aeruginosa (17.8%), followed by S. aureus (14.2%), K. pneumonia and P. mirabilis (12.5% each). The resistance markers observed was ESBL producer, AmpC producer, MBL producer, Methicillin resistance and Inducible Clindamycin Resistance (ICR).

CONCLUSION

Due to the injudicious use of antibiotics, antibiotic resistance has been increased in all types of soft tissue infections. The empirical formula for the treatment of DFIs should be decided for given geographical reasons according to antimicrobial susceptibility profile from particular geographical area or health care institute.

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.

Discovery of β-sitosterol's effects on molecular changes in rat diabetic wounds and its impact on angiogenesis and macrophages

Diabetes care, particularly for diabetic foot ulcers (DFUs)-related complications, increases treatment costs substantially. Failure to provide timely and appropriate treatment for severe DFUs significantly increases amputation risk. Neovascularization and macrophage polarization play an important role in diabetic wound healing during different stages of the wound repair process. Therefore, a new treatment method that promotes neovascularization and macrophage polarization may accelerate diabetic wound healing. β-sitosterol possesses anti-inflammatory, lipid-lowering, and antidiabetic properties. However, its therapeutic potential in diabetic wound healing remains underexplored. This study evaluated the healing effects of β-sitosterol on diabetic ulcer wounds in rats. We found that β-sitosterol can promote angiogenesis, alternatively activated macrophages (M2 macrophage) proliferation, and collagen synthesis in diabetic wounds. Transcriptomics analysis and proteomics analysis revealed that MAPK, mTOR and VEGF signaling pathways were enriched in β-sitosterol-treated wounds. Molecular docking revealed Ndufb5 maybe the target of β-sitosterol-treated wounds. Our findings confirm the significant diabetic wound healing effects of β-sitosterol in a rat model. β-sitosterol treatment to diabetic wounds accelerates wound healing through promoting M2 macrophage proliferation and angiogenesis. Interestingly, we also found that the process of M2 macrophage proliferation accompanies angiogenesis. Thus, β-sitosterol may be a promising therapeutic approach to enhance diabetic wound healing and reduce amputation in diabetes.

Photodynamic antibacterial application of TiO2/curcumin/hydroxypropyl-cyclodextrin and its konjac glucomannan composite films

Although photodynamic therapy (PDT) has great advantages for the treatment of bacterial infections, photosensitizers (PSs) often have many disadvantages that limit their application. Improving the shortcomings of PSs and developing efficient PDT antimicrobial materials remain serious challenges. In this study, a nanocomposite drug (TiO2/curcumin/hydroxypropyl-cyclodextrin, TiO2/Cur/HPCD) was constructed and combined with konjac glucomannan to form composite films (TiO2/Cur/HPCD films, KTCHD films). The stabilities of TiO2 and Cur were improved in the presence of HPCD. The particle size of TiO2/Cur/HPCD was approximately 33.9 nm, and the addition of TiO2/Cur/HPCD enhanced the mechanical properties of the films. Furthermore, TiO2/Cur/HPCD and KTCHD films exhibited good biocompatibility and PDT antibacterial effects. The antibacterial rate of TiO2/Cur/HPCD was 74.46 % against MRSA at 500 μg/mL and 99.998 % against E. coli at 400 μg/mL, while it was adsorbed on the surface of bacteria to improve the effectiveness of the treatment. In addition, studies in mice confirmed that TiO2/Cur/HPCD and KTCHD films can treat bacterial infections and promote wound healing, with a highest wound healing rate of 84.6 % in the KTCHD-10 films + Light group on day 12. Overall, TiO2/Cur/HPCD is a promising nano-antibacterial agent and KTCHD films have the potential to be employed as antibacterial and environment-friendly trauma dressings.

Absence of Synergism between a Dual-AMP Biogel and Antibiotics Used as Therapeutic Agents for Diabetic Foot Infections

Diabetic foot infections (DFIs) are frequently linked to diabetic-related morbidity and death because of the ineffectiveness of conventional antibiotics against multidrug-resistant bacteria. Pexiganan and nisin A are antimicrobial peptides (AMPs), and their application may complement conventional antibiotics in DFI treatment. A collagen 3D model, previously established to mimic a soft-tissue collagen matrix, was used to evaluate the antibacterial efficacy of a guar gum gel containing pexiganan and nisin alone and combined with three antimicrobials toward the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa isolated from infected foot ulcers. Antimicrobials and bacterial diffusion were confirmed by spot-on-lawn and bacterial growth by bacterial count (cfu/mL). Our main conclusion was that the dual-AMP biogel combined with gentamicin, clindamycin, or vancomycin was not able to significantly reduce bacterial growth or eradicate S. aureus and P. aeruginosa DFI isolates. We further reported an antagonism between dual-AMP and dual-AMP combined with antibiotics against S. aureus.

Quantitative Imaging of the Action of vCPP2319, an Antimicrobial Peptide from a Viral Scaffold, against Staphylococcus aureus Biofilms of a Clinical Isolate

The formation of biofilms is a common virulence factor that makes bacterial infections difficult to treat and a major human health problem. Biofilms are bacterial communities embedded in a self-produced matrix of extracellular polymeric substances (EPS). In this work, we show that vCPP2319, a polycationic peptide derived from the capsid protein of Torque teno douroucouli virus, is active against preformed Staphylococcus aureus biofilms produced by both a reference strain and a clinical strain isolated from a diabetic foot infection, mainly by the killing of biofilm-embedded bacteria. The direct effect of vCPP2319 on bacterial cells was imaged using atomic force and confocal laser scanning microscopy, showing that the peptide induces morphological changes in bacterial cells and membrane disruption. Importantly, vCPP2319 exhibits low toxicity toward human cells and high stability in human serum. Since vCPP2319 has a limited effect on the biofilm EPS matrix itself, we explored a combined effect with α-amylase (EC 3.2.1.1), an EPS matrix-degrading enzyme. In fact, α-amylase decreases the density of S. aureus biofilms by 2.5-fold. Nonetheless, quantitative analysis of bioimaging data shows that vCPP2319 partially restores biofilm compactness after digestion of the polysaccharides, probably due to electrostatic cross-bridging of the matrix nucleic acids, which explains why α-amylase fails to improve the antibacterial action of the peptide.

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.

Nisin Z Potential for the Control of Diabetic Foot Infections Promoted by Pseudomonas aeruginosa Persisters

Diabetic foot ulcers (DFU) are a major complication of diabetes mellitus and a public health concern worldwide. The ability of P. aeruginosa to form biofilms is a key factor responsible for the chronicity of diabetic foot infections (DFIs) and frequently associated with the presence of persister cells. These are a subpopulation of phenotypic variants highly tolerant to antibiotics for which new therapeutic alternatives are urgently needed, such as those based on antimicrobial peptides. This study aimed to evaluate the inhibitory effect of nisin Z on P. aeruginosa DFI persisters. To induce the development of a persister state in both planktonic suspensions and biofilms, P. aeruginosa DFI isolates were exposed to carbonyl cyanide m-chlorophenylhydrazone (CCCP) and ciprofloxacin, respectively. After RNA extraction from CCCP-induced persisters, transcriptome analysis was performed to evaluate the differential gene expression between the control, persisters, and persister cells exposed to nisin Z. Nisin Z presented a high inhibitory effect against P. aeruginosa persister cells but was unable to eradicate them when present in established biofilms. Transcriptome analysis revealed that persistence was associated with downregulation of genes related to metabolic processes, cell wall synthesis, and dysregulation of stress response and biofilm formation. After nisin Z treatment, some of the transcriptomic changes induced by persistence were reversed. In conclusion, nisin Z could be considered as a potential complementary therapy for treating P. aeruginosa DFI, but it should be applied as an early treatment or after wound debridement.

Distribution of Causative Microorganisms in Diabetic Foot Infections: A Ten-Year Retrospective Study in a Tertiary Care Hospital in Central Malaysia

Diabetes mellitus is a global pandemic, especially in Southeast Asia. Diabetic foot infection (DFI) is a common complication of this condition and causes significant morbidity and mortality in those affected. There is a lack of locally published data on the types of microorganisms and empirical antibiotics being prescribed. This paper highlights the importance of local microorganism culture and antibiotic prescription trends among diabetic foot patients in a tertiary care hospital in central Malaysia. This is a retrospective, cross-sectional study of data taken from January 2010 to December 2019 among 434 patients admitted with diabetic foot infections (DFIs) using the Wagner classification. Patients between the ages of 58 and 68 years old had the highest rate of infection. Pseudomonas Aeruginosa, Proteus spp., and Proteus mirabilis appeared to be the most isolated Gram-negative microorganisms, and Staphylococcus aureus, Streptococcus agalactiae, and MRSA appeared to be the most common Gram-positive microorganisms. The most common empirical antibiotics prescribed were ampicillin/sulbactam, followed by ciprofloxacin and ceftazidime, and the most common therapeutic antibiotics prescribed were ampicillin/sulbactam, ciprofloxacin, and cefuroxime. This study could be immensely pertinent in facilitating future empirical therapy guidelines for treating diabetic foot infections.

Bacteriostatic and Antibiofilm Efficacy of a Nisin Z Solution against Co-Cultures of Staphylococcus aureus and Pseudomonas aeruginosa from Diabetic Foot Infections

Diabetes mellitus (DM) patients frequently develop diabetic foot ulcers (DFU) which are generally infected by a community of microorganisms, mainly Staphylococcus aureus and Pseudomonas aeruginosa. These bacteria exhibit a multi-drug resistance profile and biofilm-forming ability which represent a hurdle in the treatment of diabetic foot infections (DFI). We aimed to evaluate the potential of Nisin Z, an antimicrobial peptide (AMP), as an alternative treatment for severe DFI. Nisin Z shows antibacterial activity against Gram-positive and Gram-negative bacteria and an increased antibacterial effect against Gram-negatives when added to EDTA. As such, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), and Minimum Biofilm Eradication Concentration (MBEC) were determined for Nisin Z, Nisin Z + EDTA (0.4%), and Nisin Z + EDTA incorporated into guar gum, in order to test its efficacy against S. aureus and P. aeruginosa isolated from the same DFU. Results showed that Nisin Z added to the chelation agent EDTA displayed higher antibacterial and bacteriostatic efficacy against mono and dual co-cultures of S. aureus and P. aeruginosa, and higher antibiofilm efficiency against monocultures. Nisin Z was moderately cytotoxic at 200 µg/mL. Prospect in vivo studies are needed to confirm the potential of Nisin Z supplemented with EDTA to be used as a complement to conventional antibiotic therapy for severe DFI.

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.

Fig latex inhibits the growth of pathogenic bacteria invading human diabetic wounds and accelerates wound closure in diabetic mice

Impaired wound healing is one of the most critical complications associated with diabetes mellitus. Infections and foot ulcers are major causes of morbidity for diabetic patients. The current treatment of diabetic foot ulcers, commonly used antibiotics, is associated with the development of bacterial resistance. Hence, novel and more effective natural therapeutic antibacterial agents are urgently needed and should be developed against the pathogenic bacteria inhabiting diabetic wounds. Therefore, the current study aimed to investigate the impact of fig latex on pathogenic bacteria and its ability to promote the healing process of diabetic wounds. The pathogenic bacteria were isolated from patients with diabetic foot ulcers admitted to Assiut University Hospital. Fig latex was collected from trees in the Assiut region, and its chemical composition was analyzed using GC‒MS. The antibacterial efficacy of fig latex was assessed on the isolated bacteria. An in vivo study to investigate the effect of fig latex on diabetic wound healing was performed using three mouse groups: nondiabetic control mice, diabetic mice and diabetic mice treated with fig latex. The influence of fig latex on the expression levels of β-defensin-1, PECAM-1, CCL2 and ZO-1 and collagen formation was investigated. The GC‒MS analysis demonstrated the presence of triterpenoids, comprising more than 90% of the total latex content. Furthermore, using a streptozotocin-induced diabetic mouse model, topical treatment of diabetic wound tissues with fig latex was shown to accelerate and improve wound closure by increasing the expression levels of β-defensin-1, collagen, and PECAM-1 compared to untreated diabetic wounds. Additionally, fig latex decreased the expression levels of ZO-1 and CCL2.

MRSA in Humans, Pets and Livestock in Portugal: Where We Came from and Where We Are Going

Over the years, molecular typing of methicillin-resistant S. aureus (MRSA) has allowed for the identification of endemic MRSA strains and pathogenic strains. After reaching a peak of predominance in a given geographic region, MRSA strains are usually replaced by a new strain. This process is called clonal replacement and is observed worldwide. The worldwide spread of hospital-associated MRSA (HA-MRSA), community-associated MRSA (CA-MRSA) and livestock-associated MRSA (LA-MRSA) clones over the last few decades has allowed this microorganism to be currently considered a pandemic. In Portugal, most HA-MRSA infections are associated with EMRSA-15 (S22-IV), New York/Japan (ST5-II) and Iberian (ST247-I) clones. Regarding the strains found in the community, many of them are frequently associated with the hospital environment, namely the Pediatric, Brazilian and Iberian clones. On the other hand, a strain that is typically found in animals, MRSA clonal complex (CC) 398, has been described in humans as colonizing and causing infections. The ST398 clone is found across all animal species, particularly in farm animals where the economic impact of LA-MRSA infections can have disastrous consequences for industries. In contrast, the EMRSA-15 clone seems to be more related to companion animals. The objective of this review is to better understand the MRSA epidemiology because it is, undoubtedly, an important public health concern that requires more attention, in order to achieve an effective response in all sectors.

Nisin Mutant Prevention Concentration and the Role of Subinhibitory Concentrations on Resistance Development by Diabetic Foot Staphylococci

The most prevalent microorganism in diabetic foot infections (DFI) is Staphylococcus aureus, an important multidrug-resistant pathogen. The antimicrobial peptide nisin is a promising compound for DFI treatment, being effective against S. aureus. However, to avoid the selection of resistant mutants, correct drug therapeutic doses must be established, being also important to understand if nisin subinhibitory concentrations (subMIC) can potentiate resistant genes transfer between clinical isolates or mutations in genes associated with nisin resistance. The mutant selection window (MSW) of nisin was determined for 23 DFI S. aureus isolates; a protocol aiming to prompt vanA horizontal transfer between enterococci to clinical S. aureus was performed; and nisin subMIC effect on resistance evolution was assessed through whole-genome sequencing (WGS) applied to isolates subjected to a MEGA-plate assay. MSW ranged from 5–360 μg/mL for two isolates, from 5–540 μg/mL for three isolates, and from 5–720 μg/mL for one isolate. In the presence of nisin subMIC values, no transconjugants were obtained, indicating that nisin does not seem to promote vanA transfer. Finally, WGS analysis showed that incubation in the presence of nisin subMIC did not promote the occurrence of significant mutations in genes related to nisin resistance, supporting nisin application to DFI treatment.

Bacterial responsive hydrogels based on quaternized chitosan and GQDs-ε-PL for chemo-photothermal synergistic anti-infection in diabetic wounds

Clinically, systemic antibiotic therapy and traditional dressings care are not satisfactory in treating chronic diabetic ulcers (DU). Therefore, we presented sprayable antibacterial hydrogel for effective treatment of DU by using antibacterial macromolecules (quaternized chitosan, QCS, Mn ≈ 1.5 × 10⁵), photothermal antibacterial nanoparticles (ε-poly-l-lysine grafted graphene quantum dots, GQDs-ε-PL) and miocompatible macromolecules (benzaldehyde-terminated four-arm poly(ethylene glycol), 4 arm PEG-BA) as materials. The results revealed that the hydrogel could be in situ formed in 70-89 s through dynamic imine bonds crosslinking and exhibited a pH-dependent swelling ability and degradability. The hydrogel could respond to bacterial triggered acidic environment to play a synergistic effect of chemotherapy and xenon light irradiated PTT, leading to the rupture of the bacterial membrane and the inactivation of bacteria, promoting the migration and proliferation of fibroblast cell, enhancing the adhesion of platelet endothelial cell, and finally accelerating the healing of infected diabetic wound. Moreover, the hydrogel displayed self-healing, hemostatic, and biocompatible abilities, which could provide a better healing environment for wound and further promote wound healing. Hence, the multifunctional hydrogel is expected to be a potential dressing for the clinical treatment of DU.

Association of PVL Gene in MSSA and MRSA Strains among Diabetic Ulcer Patients from Odisha, India

Staphylococcus aureus has emerged as an important pathogen among diabetic foot ulcers in patients with diabetes. Infections with S. aureus in diabetic ulcers need surveillance of resistant microbial profile to provide the basis for empirical therapy for the reduction of lower extremities amputation. Panton valentine leucocidin (PVL) is considered as one of the major virulence gene of S. aureus which is responsible for destruction of white blood cells and tissue necrosis. This pore forming cytotoxin gene is carried out by both methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. The present study described the prevalence of PVL gene in MSSA and MRSA strains isolated from diabetic ulcer patients treated during November, 2019 to January, 2021 from a tertiary care hospital, Odisha. Infected tissue and blood samples from these patients were collected aseptically and sub-cultured using different media and standard techniques. The isolated genomic DNA of MSSA and MRSA strains were subjected to PCR assay for the detection of PVL gene. Two hundred ten S. aureus out of 402 diabetic ulcer patients were isolated having 59.52% MSSA and 40.47% MRSA strains. Wagner's grade III and grade IV ulcers were most prevalent in these ulcer patients. The prevalence of PVL gene in MSSA strains was more in comparison to MRSA strains. Forty five resistance patterns were observed from the antibiogram profiles of S. aureus. The present study highlighted that PVL gene could not be a marker for the detection of MRSA and MSSA strains in diabetic ulcer patients.

Aeromonas spp. Prevalence, Virulence, and Antimicrobial Resistance in an Ex Situ Program for Threatened Freshwater Fish—A Pilot Study with Protective Measures

Simple Summary

Knowledge regarding best practices to prevent bacterial disease and antimicrobial resistance acquisition in aquatic ex situ programs is limited. This pilot study aimed to investigate the role of protective measures in the prevalence, antimicrobial resistance profiles, and virulence signatures of Aeromonas spp. in Portuguese nase (Iberochondrostoma lusitanicum) kept in an ex situ program. Fish were randomly divided into two tanks (i.e., with and without protective measures). Bacterial sampling was performed weekly for 5 weeks, and Aeromonas spp. prevalence, antimicrobial resistance, and virulence signatures were compared. We observed an increase in antimicrobial resistance among collected isolates over the experiment duration, with a trend of Aeromonas spp. prevalence and virulence decreasing when using protective measures. This pilot study sheds light on Aeromonas spp. prevalence, antimicrobial resistance, and virulence dynamics in aquatic ex situ programs, while constituting a first approach in the determination of the potential use of protective measures in such settings.

Abstract

Ex situ breeding programs are important conservation tools for endangered freshwater fish. However, developing husbandry techniques that decrease the likelihood of disease, antimicrobial resistance, and virulence determinants acquisition during this process is challenging. In this pilot study, we conducted a captivity experiment with Portuguese nase (Iberochondrostoma lusitanicum), a critically endangered leuciscid species, to investigate the influence of simple protective measures (i.e., material disinfection protocols and animal handling with gloves) on the dynamics of a potential pathogenic genus, Aeromonas, as well as its virulence profiles and antimicrobial resistance signatures. Our findings show that antimicrobial resistance in Aeromonas spp. collected from I. lusitanicum significantly increased during the extent of the assay (5 weeks), with all isolates collected at the end of the study classified as multidrug-resistant. Additionally, humans handling fishes without protective measures were colonized by Aeromonas spp. The use of protective measures suggested a decreasing trend in Aeromonas spp. prevalence in I. lusitanicum, while bacterial isolates displayed significantly lower virulence index values when virulence phenotypical expression was tested at 22 °C. Despite this study representing an initial trial, which needs support from further research, protective measures tested are considered a simple tool to be applied in ex situ breeding programs for aquatic animals worldwide. Furthermore, current results raise concern regarding antimicrobial resistance amplification and zoonotic transmission of Aeromonas spp. in aquatic ex situ programs.

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

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

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

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

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

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

Influence of Nisin-Biogel at Subinhibitory Concentrations on Virulence Expression in Staphylococcus aureus Isolates from Diabetic Foot Infections

A new approach to diabetic foot infections (DFIs) has been investigated, using a nisin-biogel combining the antimicrobial peptide (AMP) nisin with the natural polysaccharide guar-gum. Since in in vivo conditions bacteria may be exposed to decreased antimicrobial concentrations, known as subinhibitory concentrations (sub-MICs), effects of nisin-biogel sub-MIC values corresponding to 1/2, 1/4 and 1/8 of nisin's minimum inhibitory concentration (MIC) on virulence expression by six Staphylococcus aureus DFI isolates was evaluated by determining bacteria growth rate; expression of genes encoding for staphylococcal protein A (spA), coagulase (coa), clumping factor A (clfA), autolysin (atl), intracellular adhesin A (icaA), intracellular adhesin D (icaD), and the accessory gene regulator I (agrI); biofilm formation; Coa production; and SpA release. Nisin-biogel sub-MICs decreased bacterial growth in a strain- and dose-dependent manner, decreased agrI, atl and clfA expression, and increased spA, coa, icaA and icaD expression. Biofilm formation increased in the presence of nisin-biogel at 1/4 and 1/8 MIC, whereas 1/2 MIC had no effect. Finally, nisin-biogel at sub-MICs did not affect coagulase production, but decreased SpA production in a dose-dependent manner. Results highlight the importance of optimizing nisin-biogel doses before proceeding to in vivo trials, to reduce the risk of virulence factor's up-regulation due to the presence of inappropriate antimicrobial concentrations.

Phenotypic profile and antibiogram of biofilm-producing bacteria isolates from diabetic foot ulcers in Zaria, Nigeria

Background

Diabetic foot ulcers (DFUs) present with high morbidity and reduce patient's quality of life. There is a gross paucity of data on biofilm-producing bacteria in DFU Infection in North-Western Nigeria. The study sought to determine the biofilm-forming ability of bacteria isolates from DFUs and determine their antimicrobial susceptibility pattern in Zaria, North-Western Nigeria.

Materials and Methods

This hospital-based cross-sectional study of patients with DFUs was conducted from June 2018 to February 2020. Consecutive biopsies were aseptically collected. Bacteria were isolated and identified using a Microgen kit. Biofilm forming ability and antibiogram of isolates were determined using microtitre plate and disk diffusion methods, respectively.

Results

Of the 225 participants enrolled, males constituted the majority, 144 (64.0%) with 88 (36.0%) females, the median age of participants was 54 (48-60) years, and the age range was 36-77 years. A total of 172 bacteria were isolated, and 123 (71.5%) were biofilm producers. Staphylococcus aureus (26.7%) was the highest biofilm producer, while Citrobacter freundii and Stenotrophomonas maltophilia were the least biofilm producers, 1 (0.6%) each. A disproportionate resistance pattern was demonstrated among the biofilm and non-biofilm producers against the cephalosporins tested, ceftazidime (68% vs. 18%), ceftriaxone (50% vs. 8.0%) and cefotaxime (21% vs. 0.0%). About 46% and 68% of the biofilm producers were resistant to gentamycin and ciprofloxacin, respectively. While only 2% of the non-biofilm producers were resistant to imipenem, 11% of the biofilm producers were resistant to it.

Conclusion

These findings revealed a high proportion of biofilm-producing bacteria and were more resistant than non-biofilm producers.

The Profile of Microbiological Pathogens in Diabetic Foot Ulcers

Diabetic foot, a main complication of diabetes mellitus, renders the foot susceptible to infection, and may eventually lead to non-traumatic limb amputation due to the deterioration of diabetic foot ulcers (DFUs). Characterizing the pathogen spectrum and antibiotic susceptibility is critical for the effective treatment of DFUs. In the current study, the characteristics and antibiotic susceptibility of the pathogen spectrum were analyzed. Secretions from the DFUs of 102 patients were cultured, and dominant pathogens were identified by using test cards. Antibiotic susceptibility of dominant pathogens was assayed by the Kirby–Bauer assay. We found that the dominant pathogens varied with age, duration of diabetes, blood sugar control, and the initial cause of ulcers. Moreover, the dominant pathogens were susceptible to at least one antibiotic. However, the antibacterial efficacy of several commonly used antibiotics decreased from 2016 to 2019. Our study indicates that the identification of dominant pathogens and antibiotic susceptibility testing is essential for the treatment of DFUs with effective antibiotics, while the abuse of antibiotics should be strictly restrained to reduce the generation of antibiotic-resistant strains.

Culturomics Approach to Identify Diabetic Foot Infection Bacteria

The main goal of the study was to evaluate the usefulness of the culturomics approach in the reflection of diabetic foot infections (DFIs) microbial compositions in Poland. Superficial swab samples of 16 diabetic foot infection patients (Provincial Polyclinical Hospital in Toruń, Poland) were subjected to culturing using 10 different types of media followed by the identification via the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and Biotyper platform. Identified 204 bacterial isolates representing 18 different species—mostly Enterococcus faecalis (63%) and Staphylococcus aureus (44%). Most of the infections (81%) demonstrated a polymicrobial character. Great differences in the species coverage, the number of isolated Gram-positive and Gram-negative bacteria, and the efficiency of the microbial composition reflection between the investigated media were revealed. The use of commonly recommended blood agar allowed to reveal only 53% of the entire microbial composition of the diabetic foot infection samples, which considerably improved when the chromagar orientation and vancomycin-resistant enterococi agar were applied. In general, efficiency increased in the following order: selective < universal < enriched < differential media. Performed analysis also revealed the impact of the culture media composition on the molecular profiles of some bacterial species, such as Corynebacterium striatum, Proteus mirabilis or Morganella morganii that contributed to the differences in the identification quality. Our results indicated that the culturomics approach can significantly improve the accuracy of the reflection of the diabetic foot infections microbial compositions as long as an appropriate media set is selected. The chromagar orientation and vancomycin-resistant enterococi agar media which were used for the first time to study diabetic foot infection microbial profiles demonstrate the highest utility in the culturomics approach and should be included in further studies directed to find a faster and more reliable diabetic foot infection diagnostic tool.

Sympatric threatened Iberian leuciscids exhibit differences in Aeromonas diversity and skin lesions' prevalence

Assessments regarding health aspects of Iberian leuciscids are limited. There is currently an information gap regarding effects of infectious diseases on these populations and their role as a possible conservation threat. Moreover, differences in susceptibility to particular agents, such as Aeromonas spp., by different species/populations is not clear. To understand potential differences in Aeromonas diversity and load, as well as in the prevalence and proportion of skin lesions, in fishes exposed to similar environmental conditions, an observational study was implemented. Using a set of 12 individuals belonging to two sympatric Iberian leuciscid species (Squalius pyrenaicus and Iberochondrostoma lusitanicum), the skin lesion score in each individual was analyzed. Furthermore, a bacterial collection of Aeromonas spp. isolated from each individual was created and isolates' load was quantified by plate counting, identified at species level using a multiplex-PCR assay and virulence profiles established using classical phenotypic methods. The similarity relationships of the isolates were evaluated using a RAPD analysis. The skin lesion score was significantly higher in S. pyrenaicus, while the Aeromonas spp. load did not differ between species. When analyzing Aeromonas species diversity between fishes, different patterns were observed. A predominance of A. hydrophila was detected in S. pyrenaicus individuals, while I. lusitanicum individuals displayed a more diverse structure. Similarly, the virulence index of isolates from S. pyrenaicus was higher, mostly due to the isolated Aeromonas species. Genomic typing clustered the isolates mainly by fish species and skin lesion score. Specific Aeromonas clusters were associated with higher virulence indexes. Current results suggest potential differences in susceptibility to Aeromonas spp. at the fish species/individual level, and constitute important knowledge for proper wildlife management through the signalization of at-risk fish populations and hierarchization of conservation measures.

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

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

Concurrent validity of biofilm detection by wound blotting on hard-to-heal wounds

OBJECTIVE

Wound biofilms delay healing of hard-to-heal wounds. Convenient biofilm identification tools for clinical settings are currently not available, hindering biofilm-based wound management. Wound blotting with biofilm staining is a potential tool for biofilm detection, owing to its convenience. Although predictive validity of wound blotting has been established, it is necessary to confirm its concurrent validity. Furthermore, current staining systems employing ruthenium red have some disadvantages for clinical use. This study aimed to evaluate the usability of alcian blue as a substitute for ruthenium red.

METHOD

Both in vitro and in vivo clinical samples were used to investigate validity and usability.

RESULTS

The in vitro study showed that proteins and extracellular DNA in biofilms did not affect staining ability of ruthenium red and alcian blue in the detection of biofilms. In the in vivo study, using a wound biofilm model with Pseudomonas aeruginosa, the staining sensitivity of ruthenium red was 88.9% and 100% for alcian blue, with correlation coefficients of signal intensities with native polyacrylamide gel electrophoresis (PAGE) of r=0.67 (p=0.035) and r=0.67 (p=0.036) for ruthenium red and alcian blue, respectively. Results from clinical samples were r=0.75 (p=0.001) for ruthenium red and r=0.77 (p<0.001) for alcian blue. The sensitivities of wound blotting staining by ruthenium red and alcian blue were very high and had a good correlation with native PAGE analysis.

CONCLUSION

Because the alcian blue procedure is more convenient than the ruthenium red procedure, wound blotting with alcian blue staining would be a promising tool to guide clinicians in delivering biofilm-based wound management.

Molecular Epidemiology, Virulence Traits and Antimicrobial Resistance Signatures of Aeromonas spp. in the Critically Endangered Iberochondrostoma lusitanicum Follow Geographical and Seasonal Patterns

Despite the fact that freshwater fish populations are experiencing severe declines worldwide, our knowledge on the interaction between endangered populations and pathogenic agents remains scarce. In this study, we investigated the prevalence and structure of Aeromonas communities isolated from the critically endangered Iberochondrostoma lusitanicum, a model species for threatened Iberian leuciscids, as well as health parameters in this species. Additionally, we evaluated the virulence profiles, antimicrobial resistance signatures and genomic relationships of the Aeromonas isolates. Lesion prevalence, extension and body condition were deeply affected by location and seasonality, with poorer performances in the dry season. Aeromonas composition shifted among seasons and was also different across river streams. The pathogenic potential of the isolates significantly increased during the dry season. Additionally, isolates displaying clinically relevant antimicrobial resistance phenotypes (carbapenem and fluroquinolone resistance) were detected. As it inhabits intermittent rivers, often reduced to disconnected pools during the summer, the dry season is a critical period for I. lusitanicum, with lower general health status and a higher potential of infection by Aeromonas spp. Habitat quality seems a determining factor on the sustainable development of this fish species. Also, these individuals act as reservoirs of important antimicrobial resistant bacteria with potential implications for public health.

Multicentre study of the burden of multidrug-resistant bacteria in the aetiology of infected diabetic foot ulcers

Background

Infected diabetic foot ulcer (IDFU) is a public health issue and the leading cause of non-traumatic limb amputation. Very few published data on IDFU exist in most West African countries.

Objective

The study investigated the aetiology and antibacterial drug resistance burden of IDFU in tertiary hospitals in Osun state, Nigeria, between July 2016 and April 2017.

Methods

Isolates were cultured from tissue biopsies or aspirates collected from patients with IDFU. Bacterial identification, antibiotic susceptibility testing and phenotypic detection of extended-spectrum beta-lactamase and carbapenemase production were done by established protocols. Specific resistance genes were detected by polymerase chain reaction.

Results

There were 218 microorganisms isolated from 93 IDFUs, comprising 129 (59.2%) Gram-negative bacilli (GNB), 59 (27.1%) Gram-positive cocci and 29 (13.3%) anaerobic bacteria. The top five facultative anaerobic bacteria isolated were: Staphylococcus aureus (34; 15.6%), Escherichia coli (23; 10.6%), Pseudomonas aeruginosa (20; 9.2%), Klebsiella pneumoniae (19; 8.7%) and Citrobacter spp. (19; 8.7%). The most common anaerobes were Bacteroides spp. (7; 3.2%) and Peptostreptococcus anaerobius (6; 2.8%). Seventy-four IDFUs (80%) were infected by multidrug-resistant bacteria, predominantly methicillin-resistant S. aureus and GNB producing extended-spectrum β-lactamases, mainly of the CTX-M variety. Only 4 (3.1%) GNB produced carbapenemases encoded predominantly by bla _VIM. Factors associated with presence of multidrug-resistant bacteria were peripheral neuropathy (adjusted odds ratio [AOR] = 4.05, p = 0.04) and duration of foot infection of more than 1 month (AOR = 7.63, p = 0.02).

Conclusion

Multidrug-resistant facultative anaerobic bacteria are overrepresented as agents of IDFU. A relatively low proportion of the aetiological agents were anaerobic bacteria.

Microbiological profile of diabetic foot ulcers in Kuwait

Introduction

Diabetic foot ulcers (DFU) and infection (DFI) are a major diabetes-related problem around the world due to the high prevalence of diabetes in the population. The aim of our study was to determine the microbiological profile of infected ulcers in patients attending Dasman Diabetes Institute (DDI) clinics in Kuwait and to analyze the distribution of microbial isolates according to wound grade, sex, age and diabetes control.

Methods

We collected and analyzed clinical data and samples from 513 diabetic patients with foot ulcers referred to our podiatry clinic at DDI from Jan 2011 till Dec 2017.

Results

We show a higher prevalence of DFU in men than in women, and a greater percentage of DFU occurred in men at an earlier age (p<0.05). Only about half of the DFU were clinically infected (49.3%) but 92% of DFU showed bacterial growth in the microbiological lab analysis. In addition, we isolated more monomicrobial (57.3%) than polymicrobial (34.8%) DFI and representing an average of 1.30 pathogens per patient. The presence of Gram-positive and Gram-negative strains was comparable between men and women regardless their age or glucose levels. Interestingly, more Gram-positive strains are present in ulcers without ischemia while more Gram-negative strains are present in ulcers with ischemia (p<0.05). While Staphylococcus aureus was common in infected ulcers without ischemia, Pseudomonas aeruginosa was predominant in ulcers with infection and ischemia, regardless of ulcer depth. Finally, a higher percentage of women has controlled HbA1c levels (19.41% versus 11.95% in men) and more women in this group displayed non-infected wounds (60.6% and 43.90% for women and men, respectively).

Conclusion

Our results provide an updated picture of the DFI patterns and antibiotics resistance in patients attending Dasman Diabetes Institute (DDI) clinics in Kuwait which might help in adopting the appropriate treatment of infected foot and improving clinical outcomes.

Microbiological profile and antimicrobial resistance among diabetic foot infections in Lebanon

Diabetic Foot Infection (DFI) is a challenging complication of diabetes mellitus with a high burden in the Middle East where there is a marked increase in diabetes prevalence and complications. Early detection of DFI and the infectious organisms could result in the early initiation of appropriate antibiotic therapy and improved outcomes. DFI microbiological profiles differ between countries. In our region, Western guidelines are used when initiating treatment for DFI in the absence of local guidance. The purpose of our study was to determine the microbiologic profile and antimicrobial susceptibility of the DFI admissions at a large tertiary referral centre in Beirut and review other reported series in Lebanon and our region. This is a retrospective observational study of patients with DFI admitted to the American University of Beirut Medical Centre from January 2008 to June 2017. The bacteriologic isolation and antimicrobial susceptibility tests were performed according to standard microbiological methods. Between 2008 and 2017, 319 diabetic patients with DFU were admitted to AUBMC, and deep-tissue cultures were taken for 179 patients. From 179 deep tissue cultures, 314 bacterial isolates were obtained. Fifty-four percent of patients had the polymicrobial infection. Aerobic gram-negative rods (GNR) were more prevalent than gram-positive cocci (GPC) (55%, 39%, respectively). The most common isolate was Escherichia coli (15%) followed by Enterococcus (14%) and Pseudomonas aeruginosa (11%). Staphylococcus aureus isolates accounted for 9% with 50% of them being methicillin-resistant (MRSA). Among Enterobacteriaceae, 37% of isolates were fluoroquinolone-resistant, 25% were ESBL producers, and 2% were carbapenem-resistant. Antibiotic resistance was significantly associated with prior usage of antibiotics. Anaerobes were isolated in 1% and Candida species in 5% of isolates. The sensitivity, specificity, PPV, and NPV of swab culture recovery of pathogens compared with deep tissue culture were (76%, 72%, 76%, 72%) and (94%, 81%, 91%, 86%) for gram-positive and gram-negative organisms, respectively. The microbiological profile of DFI in Lebanon is comparable to other countries in the MENA region with big differences compared with the West. Therefore, it is imperative to develop local guidelines for antimicrobial treatment. The high prevalence of GNR in DFI and the high fluoroquinolone resistance should be taken into consideration when choosing empiric antibiotics. Empiric treatment for MRSA or Pseudomonas does not appear necessary except for patients with specific risk factors.

Influence of Storage on the Antimicrobial and Cytotoxic Activities of a Nisin-biogel with Potential to be Applied to Diabetic Foot Infections Treatment

Staphylococcus aureus is the most prevalent pathogen in diabetic foot infections (DFIs). In addition to its ability to express several virulence factors, including the formation of recalcitrant biofilms, S. aureus is also becoming increasingly resistant to most antibiotics used in clinical practice. The search for alternative treatment strategies for DFI is urgently needed. Antimicrobial peptides (AMPs), namely, nisin, are emerging as potential new therapeutics for managing DFIs. Our team has developed a nisin-guar gum biogel to be applied to DFIs. In this study, to confirm its future in vivo applicability, we evaluated the influence of four storage temperatures (−20 °C, 4 °C, 22 °C, and 37 °C) during a 24 months storage period on its antimicrobial activity towards DFI S. aureus, and its cytotoxicity, to a human keratinocyte cell line. When stored at temperatures below 22 °C, the biogel antimicrobial activity was not significantly influenced by storage duration or temperature. Moreover, nisin incorporated within the guar gum biogel exhibited no significant levels of cytotoxicity on human keratinocyte cells, confirming its potential for DFIs therapeutics. In conclusion, results confirm that the nisin-biogel is a potential candidate to be used as an alternative or complement compound for conventional DFI therapeutics.

Multidrug-resistant bacteria in diabetic foot infections: Experience from a portuguese tertiary centre

In recent years, the emergence of antibiotic resistant pathogens made increasingly difficult to establish appropriate empiric antimicrobial therapy protocols for acute diabetic foot infection (DFI) treatment. Early recognition of the population at-risk for multidrug-resistant (MDR) bacterial infection is of paramount importance in order to decrease large-spectrum antibiotic overuse. This study used retrospective cohort study in a multidisciplinary tertiary diabetic foot unit. Patients with severe DFI were included and divided according to their infection resistance profile (susceptible vs MDR bacteria). Data regarding their comorbidities and length of hospital stay were collected. The primary endpoint was to determine the risk factors for MDR infections and to evaluate if these were associated with an increased length of stay (LOS). A total of 112 microbial isolates were included. Predominance of Gram-positive bacteria was observed and 22.3% of isolated bacteria were MDR. Previous hospitalisation was associated with a higher likelihood of MDR infection. MDR bacterial infection was also associated with an increased LOS (P = .0296). Our study showed a high incidence of MDR bacteria in patients with a DFI, especially in those who had a recent hospitalisation. MDR infections were associated with a prolonged LOS and represent a global public health issue for which emergent measures are needed.

A study on diabetic foot ulcers in Central rural India to formulate empiric antimicrobial therapy

AIM

This study was carried out on patients with diabetic foot ulcer (DFU) to assess the clinical characteristics, spectrum of microbial flora, antibiotic sensitivity, and devise an empiric antimicrobial therapy.

MATERIAL METHODS

Clinical data and tissue samples were collected from 105 diabetic foot ulcer patients between December 2018 and November 2019. The collected samples were processed as per Clinical and Laboratory Standards Institute guidelines and clinical and microbiological data was analyzed.

RESULTS

In this study of 105 patients, DFU was most common in males in 5th and 6th decade of life. Majority of patients had poor glycemic control and neuropathy. Of 110 bacterial isolates obtained from 97 samples, 73.7% were Gram-negative bacteria, and 27.3% were Gram-positive. Most of samples (48.6%) showed growth of single bacteria, growth of two bacteria and polymicrobial growth was seen in 28.6% and 15.2% of tissue samples respectively of which. Pseudomonas was predominant isolate (27.3%) sensitive to imipenem (90%), amikacin (86.6%), gentamicin (83.3%), and cefotaxime (80%) followed by Staphylococcus aureus (19.1%) sensitive to amikacin and gentamicin (100%), and ofloxacin (90%). Pseudomonas, E. coli, Proteus and Klebsiella were highly resistant to ampicillin and amoxicillin-clavulanic acid.

CONCLUSION

This study showed DFU are common in 5th and 6th decades of life. Gram-negative bacteria are predominant infective organism. Most of both Gram-negative and Gram-positive bacteria are resistant to variable degrees to commonly used antibiotics and sensitive to aminoglycosides. Amikacin and gentamicin can be used as empiric antibiotics for treatment of DFU infections.

Microbiologic characteristics and antibiotic resistance rates of diabetic foot infections

PURPOSE

the purpose of this research was to identify the sociodemographic and microbiological characteristics and antibiotic resistance rates of patients with diabetic foot infections, hospitalized in an emergency reference center.

METHODS

it was an observational and transversal study. The sociodemographic data were collected by direct interview with the patients. During the surgical procedures, specimens of tissue of the infected foot lesions were biopsied to be cultured, and for bacterial resistance analysis.

RESULTS

the sample consisted of 105 patients. The majority of patierns were men, over 50 years of age, married and with low educational level. There was bacterial growth in 95 of the 105 tissue cultures. In each positive culture only one germ was isolated. There was a high prevalence of germs of the Enterobacteriaceae family (51,5%). Gram-negative germs were isolated in 60% of cultures and the most individually isolated germs were the Gram-positive cocci, Staphylococcus aureus (20%) and Enterococcus faecalis (17,9%). Regarding antibiotic resistance rates, a high frequency of Staphylococcus aureus resistant to methicillin (63,0%) and to ciprofloxacin (55,5%) was found; additionally, 43,5% of the Gram-negative isolated germs were resistant to ciprofloxacin.

CONCLUSIONS

the majority of patients were men, over 50 years of age, married and with low educational level. The most prevalent isolated germs from the infected foot lesions were Gram-negative bacteria, resistant to ciprofloxacin, and the individually most isolated germ was the methicillin resistant Staphylococcus aureus.

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.

Pexiganan in Combination with Nisin to Control Polymicrobial Diabetic Foot Infections

Diabetic foot ulcers (DFUs) are major complications of Diabetes mellitus being responsible for significant morbidity and mortality. DFUs frequently become chronically infected by a complex community of bacteria, including multidrug-resistant and biofilm-producing strains of Staphylococcus aureus and Pseudomonas aeruginosa. Diabetic foot infections (DFI) are often recalcitrant to conventional antibiotics and alternative treatment strategies are urgently needed. Antimicrobial Peptides (AMPs), such as pexiganan and nisin, have been increasingly investigated and reported as effective antimicrobial agents. Here, we evaluated the antibacterial potential of pexiganan and nisin used in combination (dual-AMP) to control the growth of planktonic and biofilm co-cultures of S. aureus and P. aeruginosa clinical strains, co-isolated from a DFU. A DFU collagen three-dimensional (3D) model was used to evaluate the distribution and efficacy of AMPs locally delivered into the model. The concentration of pexiganan required to inhibit and eradicate both planktonic and biofilm-based bacterial cells was substantially reduced when used in combination with nisin. Moreover, incorporation of both AMPs in a guar gum delivery system (dual-AMP biogel) did not affect the dual-AMP antimicrobial activity. Importantly, the application of the dual-AMP biogel resulted in the eradication of the S. aureus strain from the model. In conclusion, data suggest that the local application of the dual-AMPs biogel constitutes a potential complementary therapy for the treatment of infected DFU.

In vitro detection of porphyrin-producing wound bacteria with real-time fluorescence imaging

Aim: Fluorescence imaging can visualize polymicrobial populations in chronic and acute wounds based on porphyrin fluorescence. We investigated the fluorescent properties of specific wound pathogens and the fluorescence detected from bacteria in biofilm. Methods: Utilizing Remel Porphyrin Test Agar, 32 bacterial and four yeast species were examined for red fluorescence under 405 nm violet light illumination. Polymicrobial biofilms, supplemented with δ-aminolevulinic acid, were investigated similarly. Results: A total of 28/32 bacteria, 1/4 yeast species and polymicrobial biofilms produced red fluorescence, in agreement with their known porphyrin production abilities. Conclusion: These results identify common wound pathogens capable of producing porphyrin-specific fluorescence and support clinical observations using fluorescence imaging to detect pathogenic bacteria in chronic wounds.

Association between baseline abundance of Peptoniphilus, a Gram-positive anaerobic coccus, and wound healing outcomes of DFUs

Diabetic foot ulcers (DFUs) lead to nearly 100,000 lower limb amputations annually in the United States. DFUs are colonized by complex microbial communities, and infection is one of the most common reasons for diabetes-related hospitalizations and amputations. In this study, we examined how DFU microbiomes respond to initial sharp debridement and offloading and how the initial composition associates with 4 week healing outcomes. We employed 16S rRNA next generation sequencing to perform microbial profiling on 50 samples collected from 10 patients with vascularized neuropathic DFUs. Debrided wound samples were obtained at initial visit and after one week from two DFU locations, wound bed and wound edge. Samples of the foot skin outside of the wounds were also collected for comparison. We showed that DFU wound beds are colonized by a greater number of distinct bacterial phylotypes compared to the wound edge or skin outside the wound. However, no significant microbiome diversity changes occurred at the wound sites after one week of standard care. Finally, increased initial abundance of Gram-positive anaerobic cocci (GPAC), especially Peptoniphilus (p < 0.05; n = 5 subjects), was associated with impaired healing; thus, GPAC's abundance could be a predictor of the wound-healing outcome.

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

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

Molecular Characteristics of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Diabetic Foot Infection

Background & Objective:

Diabetic foot ulcer (DFU), is one of the most frequent causes for hospitalizations in patients with diabetes. A major problem in the treatment of DFU is the increased-incidence of methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to determine the SCCmec types of MRSA isolates and their epidemiology among patients with diabetes.

Methods:

This study was carried out on 145 diabetic patients with DFUs. The antibiotic susceptibility tests (ASTs) were performed using the disk diffusion method and E-test technique. SCCmec typing was done by multiplex PCR. Moreover, the presence of virulence toxin genes, including pvl and lukED was detected by PCR assay.

Results:

In 145 samples from which S. aureus was predominantly isolated, 19.48% were MRSA. Analysis of MRSA isolates revealed that the most prevalent SCCmec type was type IV (46.7%) followed by type III (30.0%) and type V (20.0%). One strain (3.3%) was untypeable. The prevalence of pvl and lukED was 56.7% and 100%, respectively.

Conclusion:

The high prevalence of MRSA in DFUs represents the high levels of antibiotic usage among patients with diabetes. In this study, resistance to other important clinical antibiotics was detected among MRSA isolates. The high proportion of SCCmec type IV and V strains, even in former hospitalized patients, indicates the entrance of these clones to the clinical setting.

Correlation between superficial and intra-operative specimens in diabetic foot infections: results of a cross-sectional Tunisian study

Objective

To determine the correlation between superficial, and intra-operative specimens in diabetic foot infections (DFIs).

Methods

We conducted a cross-sectional study in patients with DFIs hospitalized in a Tunisian teaching hospital. Superficial specimens were collected for all patients, and intra-operative specimens were collected in operated patients. The specimens were processed using standard microbiology techniques. Antimicrobial susceptibility testing was carried out according to the protocol established by the European Committee on Anti-microbial Susceptibility Testing. Intra-operative and superficial specimens were considered correlated if they isolated the same microorganism(s), or if they were both negative.

Results

One hundred twelve patients, 81 males and 31 females, mean age 56 years, were included. Superficial samples were positive in 77% of cases, and isolated 126 microorganisms. Among the positive samples, 71% were monomicrobial. The most frequently isolated microorganisms were Enterobacteriaceae (53%), followed by streptococci (21%) and Staphylococcus aureus (17%). Nine microorganisms (7%) were multi-drug resistant. Intra-operative samples were positive in 93% of cases. Superficial specimens were correlated to intra-operative specimens in 67% of cases. Initial antibiotic therapy was appropriate in 70% of cases. The lower-extremity amputation and the mortality rates were 41% and 1%, respectively.

Conclusion

In our study, DFIs were most frequently caused by Enterobacteriaceae and superficial specimens were correlated to intra-operative specimens in only two thirds of cases. Clinicians should emphasize on the systematic practice of intraoperative specimens in all patients with DFIs treated surgically, while well-performed superficial specimens could be useful for prescribing appropriate antibiotic therapy in other patients.

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.

Diabetic foot infections: Application of a nisin-biogel to complement the activity of conventional antibiotics and antiseptics against Staphylococcus aureus biofilms

BACKGROUND

Diabetic foot infections (DFIs) are a frequent complication of Diabetes mellitus and a major cause of nontraumatic limb amputations. The Gram-positive bacterium Staphylococcus aureus, known for its resilient biofilms and antibiotic resistant profile, is the most frequent DFI pathogen. It is urgent to develop innovative treatments for these infections, being the antimicrobial peptide (AMP) nisin a potential candidate. We have previously proposed the use of a guar gum biogel as a delivery system for nisin. Here, we evaluated the potential of the nisin-biogel to enhance the efficacy of conventional antibiotics and antiseptics against DFIs S. aureus clinical isolates.

METHODS

A collection of 23 S. aureus strains isolated from DFI patients, including multidrug- and methicillin-resistant strains, was used. The antimicrobial activity of the nisin-biogel was tested alone and in different combinations with the antiseptic chlorhexidine and the antibiotics clindamycin, gentamicin and vancomycin. Isolates' in vitro susceptibility to the different protocols was assessed using broth microdilution methods in order to determine their ability to inhibit and/or eradicate established S. aureus biofilms. Antimicrobials were added to the 96-well plates every 8 h to simulate a typical DFI treatment protocol. Statistical analysis was conducted using RCBD ANOVA in SPSS.

RESULTS

The nisin-biogel showed a high antibacterial activity against biofilms formed by DFI S. aureus. The combined protocol using nisin-biogel and chlorhexidine presented the highest efficacy in biofilm formation inhibition, significantly higher (p<0.05) than the ones presented by the antibiotics-based protocols tested. Regarding biofilm eradication, there were no significant differences (p>0.05) between the activity of the combination nisin-biogel plus chlorhexidine and the conventional antibiotic-based protocols.

CONCLUSIONS

Results provide a valuable contribution for the development of complementary strategies to conventional antibiotics protocols. A combined protocol including chlorhexidine and nisin-biogel could be potentially applied in medical centres, contributing for the reduction of antibiotic administration, selection pressure on DFI pathogens and resistance strains dissemination.

BD-2 and BD-3 increase skin flap survival in a model of ischemia and Pseudomonas aeruginosa infection

The main aim of this work was to study the usefulness of human β-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap survival in the context of a P. aeruginosa infection associated with a foreign body. The secondary endpoints assessed were: bacterial counts, and biofilm formation on the surface of the foreign body. A local ischemic environment was created by producing arterialized venous flaps in the left epigastric region of rats. Flaps were intentionally infected by placing underneath them two catheters with 105 CFU of P. aeruginosa before the surgical wounds were hermetically closed. Flap biopsies were performed 3 and 7 days post-operatively, and the specimens submitted to immunohistochemical analysis for BD-2 and BD-3, as well as to bacterial quantification. Subsequently, the catheter segments were analyzed with scanning electron microscopy (SEM). Flaps transduced with BD-2 and BD-3 showed expression of these defensins and presented increased flap survival. Rats transduced with BD-3 presented a net reduction in the number of P. aeruginosa on the surface of the foreign body and lesser biofilm formation.

Diabetic Foot Infection: Causative Pathogens and Empiric Antibiotherapy Considerations—The Experience of a Tertiary Center

Most moderate-to-severe diabetic foot infections (DFIs) require hospitalization with urgent surgical approach and administration of empiric antibiotherapy. To ensure optimal antibiotic coverage, regular microbiological background updates are imperative. The purpose is to characterize the microbiological profile and the antibiotic sensitivity pattern of the DFI causative pathogens isolated within a specialized DFI unit of a tertiary hospital, in order to establish evidence-based policies regarding empirical antibiotic use. A cross-sectional study was conducted. Microbiological cultures and corresponding antibiotic sensitivity tests collected from moderate-to-severe DFIs as a first approach to the hospitalized patient were retrieved and analyzed during a 12-month period. Two groups were analyzed: inpatients that had been previously followed at the diabetic foot clinic of the hospital and inpatients without a previous contact with the hospital services. A total of 125 isolates obtained from 87 patients were deemed for analysis. Globally, a predominance of Gram-positive bacteria was observed (60%). Staphylococcus aureus was the most common pathogen. The global ratio of methicillin-sensitive S aureus to methicillin-resistant S aureus (MRSA) was 1.3:1, with similar findings in both groups. According to the antibiotic sensitivity test results, and within the recommended empiric antibiotic regimens for DFI, piperacillin/tazobactam seems to be the most suitable option. Gram-positive bacteria prevail as the main isolates in DFIs. Screening for MRSA-specific risk factors is mandatory. When going for a first empiric therapy, piperacillin/tazobactam is recommended in this institution, and an anti-MRSA agent should be added early, if necessary. We encourage continuous monitoring for the bacterial prevalence in Portuguese diabetic foot centers as it is paramount for the decision making regarding DFI protocols.