Vancomycin-resistant Enterococcus Faecium Isolates Research Articles

Emergence of Virulent Extensively Drug-Resistant Vancomycin-Resistant Enterococci Among Diarrheic Pet Animals: A Possible Public Health Threat on the Move.

Background: Vancomycin-resistant enterococci (VRE) have become an increasing public health concern in the past few decades, being associated with serious multidrug-resistant (MDR) infections. This study was conducted to investigate the role of diarrheic pet animals as potential reservoirs for virulent extensively drug-resistant (XDR) VRE and their threat on human health. Materials and Methods: Rectal swabs were collected from 153 diarrheic pet animals (80 dogs and 73 cats). The collected swabs were cultured on CHROMagarTMVRE for the isolation of vancomycin-resistant Enterococcus faecalis and Enterococcus faecium, and then suspected colonies were identified as enterococci after Gram staining, conventional biochemical tests, and molecular techniques. VRE were basically identified using the disk diffusion method; however, molecular identification of vanA and vanB genes was carried out among confirmed VRE isolates. Moreover, three virulence genes (cytolysin A, cylA; enterococcal surface protein, esp; and hyaluronidase, hyl) were investigated in VRE isolates. Thereafter, VRE strains that harbored virulence genes were tested for antimicrobial susceptibility. Results: Eighteen out of 153 animals (11.8%) were positive for VRE, which were obtained from 15% and 8.2% of the examined dogs and cats, respectively. None of the obtained isolates carried the vanA gene, whereas the vanB gene was detected in E. faecalis (4/10) with a prevalence rate (40%). Of the obtained VRE isolates, five possessed esp and/or cylA, while all strains were negative for the hyl gene. Furthermore, four virulent VRE isolates exhibited an XDR pattern, and one isolate was MDR. Conclusion: Diarrheic pet animals could represent a potential zoonotic reservoir for virulent XDR vancomycin-resistant E. faecalis, which may have serious public health implications.

Genomic characterization of vancomycin-resistant Enterococcus faecium clonal complex 17 isolated from urine in tertiary hospitals in Northeastern Thailand.

Vancomycin-resistant Enterococci (VREs) have increasingly become a major nosocomial pathogen worldwide, earning high-priority category from the World Health Organization (WHO) due to their antibiotic resistance. Among VREs, vancomycin-resistant Enterococcus faecium (VREfm) is particularly concerning, frequently isolated and resistant to many antibiotics used in hospital-acquired infections. This study investigated VREfm isolates from rural tertiary hospitals in Northeastern Thailand based both antibiotic susceptibility testing and whole-genome sequencing. All isolates showed resistance to vancomycin, ampicillin, erythromycin, tetracycline, ciprofloxacin, norfloxacin, and rifampin. Nitrofurantoin and tigecycline resistance were also observed in nearly all isolates. Conversely, all isolates remained susceptible to chloramphenicol, daptomycin, and linezolid. Genomic characterization revealed that all VREfm isolates belonged to clonal complex 17 (CC17), primarily consisting of sequence type (ST) 80, followed by ST17, ST761, and ST117. Additionally, all isolates harbored numerous antimicrobial-resistant genes, including vanA, tet(L), tet(M), aac(6')-li, ant(6)-Ia, aph(3')-III, aac(6')-aph(2″), aph(2″)-la, ant(9)-la, erm(B), msr(C), erm(T), erm(A), fosB, dfrG, and cfr(B). Notably, all isolates contained virulence genes, for collagen adhesin (acm) and cell wall adhesin (efafm), while hylEfm (glycosyl hydrolase) was detected in VREfm ST80. This study provided important information for understanding the genomic features of VREfm isolated from urine.

Long-term carriage and evolution of VREfmLong-term carriage and evolution of vancomycin-resistant Enterococcus faecium: a genomic study on consecutive isolates.

To determine if vancomycin-resistant Enterococcus faecium (VREfm) carriers carry the same VREfm clone after a minimum follow-up of 365 days. For those carrying the same clone, we investigated the genomic evolution per year per genome. We used WGS results to assign VREfm clones to each isolate and determine clone shifts. Finally, we calculated distance in core-genome MLST alleles, and the number of SNPs between consecutive VREfm isolates from patients carrying the same VREfm clone. In total, 44.2% of patients carried the same VREfm clone, and the genomic evolution was 1.8 alleles and 2.6 SNPs per genome per year. In our population of long-term carriers, we calculated a molecular clock of 2.6 SNPs.

The first vanE-type vancomycin resistant Enterococcus faecalis isolates in Norway – phenotypic and molecular characteristics

We aimed to characterize the vanE cluster and its genetic support in the first Norwegian vanE-type isolates and assess genetic relatedness to other vanE isolates. Two vanE-type vancomycin resistant Enterococcus faecalis (vanE-VREfs) isolates (E1 and E2) recovered from the same patient 30 months apart were examined for antimicrobial susceptibility, genome sequence, vancomycin resistance induction, vanE transferability, genome mutation rate, and phylogenetic relationship to E. faecalis closed genomes and two vanE-VREfs from North America. The ST34 E1 and E2 strains expressed low-level vancomycin resistance and susceptibility to teicoplanin. Their vanE gene clusters were part of a non-transferable Tn6202. The histidine kinase part of vanSE was expressed although a premature stop codon (E1) and insertion of a transposase (E2) truncated their vanSE gene. The vancomycin resistance phenotype in E1 was inducible while constitutive in E2. E1 showed a 125-fold higher mutation rate than E2. Variant calling showed 60 variants but nearly identical chromosomal gene content and synteny between the isolates. Their genomes also showed high similarity to another ST34 vanE-VREfs from Canada. In-depth genomic analyses of the first two vanE-VREfs found in Europe identified a single chromosomal insertion site of two variants of vanE-conferring Tn6202. Single nucleotide polymorphism (SNP) and core genome multilocus sequence type (cgMLST) analyses show the genomes are different. This can be explained by the high mutation rate of E1 and acquisition of different mobile genetic elements; thus, we believe the two isolates from the same patient are genetically related. Genome similarities also suggest relatedness between the Canadian and Norwegian vanE-VREfs.

The population structure of vancomycin-resistant and -susceptible Enterococcus faecium in a low-prevalence antimicrobial resistance setting is highly influenced by circulating global hospital-associated clones.

Between 2010 and 2015 the incidence of vancomycin-resistant Enterococcus faecium (VREfm) in Norway increased dramatically. Hence, we selected (1) a random subset of vancomycin-resistant enterococci (VRE) from the Norwegian Surveillance System for Communicable Diseases (2010-15; n=239) and (2) Norwegian vancomycin-susceptible E. faecium (VSEfm) bacteraemia isolates from the national surveillance system for antimicrobial resistance in microbes (2008 and 2014; n=261) for further analysis. Whole-genome sequences were collected for population structure, van gene cluster, mobile genetic element and virulome analysis, as well as antimicrobial susceptibility testing. Comparative genomic and phylogeographical analyses were performed with complete genomes of global E. faecium strains from the National Center for Biotechnology Information (NCBI) (1946-2022; n=272). All Norwegian VREfm and most of the VSEfm clustered with global hospital-associated sequence types (STs) in the phylogenetic subclade A1. The vanB2 subtype carried by chromosomal Tn1549 integrative conjugative elements was the dominant van type. The major Norwegian VREfm cluster types (CTs) were in accordance with concurrent European CTs. The dominant vanB-type VREfm CTs, ST192-CT3/26 and ST117-CT24, were mostly linked to a single hospital in Norway where the clones spread after independent chromosomal acquisition of Tn1549. The less prevalent vanA VRE were associated with more diverse CTs and vanA carrying Inc18 or RepA_N plasmids with toxin-antitoxin systems. Only 5 % of the Norwegian VRE were Enterococcus faecalis, all of which contained vanB. The Norwegian VREfm and VSEfm isolates harboured CT-specific virulence factor (VF) profiles supporting biofilm formation and colonization. The dominant VREfm CTs in general hosted more virulence determinants than VSEfm. The phylogenetic clade B VSEfm isolates (n=21), recently classified as Enterococcus lactis, harboured fewer VFs than E. faecium in general, and particularly subclade A1 isolates. In conclusion, the population structure of Norwegian E. faecium isolates mirrors the globally prevalent clones and particularly concurrent European VREfm/VSEfm CTs. Novel chromosomal acquisition of vanB2 on Tn1549 from the gut microbiota, however, formed a single major hospital VREfm outbreak. Dominant VREfm CTs contained more VFs than VSEfm.

Fosfomycin Enhances the Inhibition Ability of Linezolid Against Biofilms of Vancomycin-Resistant Enterococcus faecium in vitro.

We explored the inhibition ability of linezolid/fosfomycin combination against biofilms of vancomycin-resistant Enterococcus faecium (VREfm) and tried to provide a theoretical basis for the treatment of VREfm biofilm-associated infections. Four clinical isolates of VREfm (No.2, No.4, No.5, and No.6) were used for this study, which were collected from the First Affiliated Hospital of Anhui Medical University. The checkerboard method was used to assess the synergistic effect of linezolid and fosfomycin. The inhibition ability of biofilm biomass was evaluated by crystal violet staining, and the metabolic activity was tested by an Alamar blue cell viability assay. Changes in biofilm formation-related genes of the strains after incubating with drugs were investigated via the quantitative real-time polymerase chain reaction (RT-qPCR). The fractional inhibitory concentration index (FICI) showed that linezolid combined with fosfomycin had a synergistic effect on all four VREfm isolates. Compared with linezolid monotherapy, linezolid combined with fosfomycin led to a significant decrease in biofilm biomass and metabolic activity, especially in the mature biofilm. The results of RT-qPCR showed linezolid combined with fosfomycin inhibition biofilm formation through the inhibition of cylA, ebpA, and gelE transcription in VREfm in the initial and mature stages. To the mature biofilm, the combination also reduced the expression of asa1, atlA, and esp. The combination of linezolid and fosfomycin represented stronger inhibitory effect on the biofilm formation of VREfm than linezolid alone.

An Outbreak of Vancomycin-Resistant Enterococci in a City Hospital Intensive Care Unit: Molecular Characterization of Resistance.

Background and Objectives: Vancomisin-resistant Enterococci (VRE), is a resistant microorganism that colonizes and causes infections in hospitalized patients. The aim of this study was to show the spread of vancomycin-resistant Enterococcus faecium (VREfm) step-by-step in all intensive care units, which started with the growth of VREfm on 2 December 2021 in the blood culture of a patient hospitalized in the anesthesia intensive care unit of our hospital and was found to have reached epidemic size in the surveys. Materials and Methods: Rectal swab samples were taken from all patients hospitalized in intensive care units, VRE colonization was determined, the VanA and VanB resistance genes associated with the vancomycin resistance of VREfm isolates were determined by PCR method, and clonal association analysis was performed by Arbitrarily Primed-PCR (AP-PCR) and PFGE (pulsed-field gel electrophoresis). Results: In our study, VRE were detected in 61 of 2601 rectal swab samples. In total, fifty-four (85.52%) of the VRE isolates were Enterococcus faecium, three (4.91%) was Enterococcus faecalis, three (4.91%) was Enterococcus gallinorum, and one (1.63%) was Enterococcus casseliflavus. It was determined that all of the 54 VREfm isolates, which were the most detected among all VRE isolates, carried the vanA gene. In the clonal association analysis of the isolates by AP-PCR and PFGE methods, it was found that they had 12 different genotypes, 48 of them were included in any cluster, the clustering rate was 88.8%, and the largest cluster was the genotype 1 cluster, with 36 isolates. Of the 54 patients with VREfm isolated recently, 18.51 percent of the clinical samples were isolated before the survey, and 9.25% were isolated after the survey. It was determined that 100% of VREfm isolates were resistant to ampicillin, levofloxacin, ciprofloxacin, high-level gentamicin, trimethoprimsulfamethoxazole, and teicoplanin, 7.4% to tigecycline, and 1.85% to linezolid. Conclusions: In our study, in the clonal association analysis performed by isolating VREfm in rectal swab samples, it was found that 88.8% of the samples were indistinguishably similar, and that the increase in the number of VREfm infections after the index case in our hospital was associated with the epidemic. VREfm infections cause long-term hospitalization, costs and also deaths, which shows the seriousness of the event, and the importance of the combination of epidemiological and molecular analysis in epidemic research.

Outbreak of vancomycin-resistant Enterococcus faecium ST1133 in paediatric patients with acute lymphoblastic leukaemia from southern Brazil

We aimed to investigate an outbreak of vancomycin-resistant Enterococcus faecium (VREfm) in paediatric patients from Hospital Pequeno Príncipe. The susceptibility profile was determined, and whole-genome sequencing (WGS) was used to analyse the genetic context of the strains. Five VREfm isolates were recovered from sterile sites and surveillance cultures of two paediatric patients with acute lymphoblastic leukaemia. Species identification was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the minimum inhibitory concentration (MIC) was assessed according to the European Committee for Antimicrobial Susceptibility Testing (EUCAST). WGS was performed to analyse the genetic context of virulence and resistance genes, and in silico multilocus sequence typing was performed to identify the sequence typing of the strains. High-level vancomycin resistance was observed in all isolates (≥256 mg/L). WGS revealed the presence of mobile genetic elements, such as plasmids (rep2, rep11a, repUS15, rep17, and rep18a), insertion sequences, and phages. Multiple resistance genes (aac(6')-aph(2"), dfrG, ermB, and vanA) and virulence genes (acm and efaAfm) were identified. All the isolates were assigned to ST117 (ST1133 - via a novel MLST), an important epidemic lineage associated with nosocomial infections and outbreaks. Our results show that the ST117 (ST1133) VREfm isolates are circulating in paediatric patients, which raises a great concern. The development of new drugs as well as the implementation of an antimicrobial stewardship program are necessary for their correct management, limiting the spread of resistance in oncohematological patients.

Concerning emergence of a new vancomycin-resistant Enterococcus faecium strain ST1299/CT1903/vanA at a tertiary university centre in South Germany

vanB-carrying vancomycin-resistant Enterococcus faecium (VREfm) of the sequence types 80 (ST80) and ST117 have dominated Germany in the past. In 2020, our hospital witnessed a sharp increase in the proportion of vanA-positive VREfm. To attempt to understand these dynamics through whole-genome sequencing (WGS) and analysis of nosocomial transmissions. At our hospital, the first VREfm isolate per patient, treated during 2020, was analysed retrospectively using specific vanA/vanB PCR, WGS, multi-locus sequence typing (MLST), and core-genome (cg) MLST. Epidemiologic links between VRE-positive patients were assessed using hospital occupancy data. Isolates from 319 out of 356 VREfm patients were available for WGS, of which 181 (56.7%) fulfilled the ECDC definition for nosocomial transmission. The high load of nosocomial cases is reflected in the overall high clonality rate with only three dominating sequence (ST) and complex types (CT), respectively: the new emerging strain ST1299 (100% vanA, 77.4% CT1903), and the well-known ST80 (90.0% vanB, 81.0% CT1065) and ST117 (78.0% vanB, 65.0% CT71). The ST1299 isolates overall, and the subtype CT1903 in particular, showed high isolate clonality, which demonstrates impressively high spreading potential. Overall, 152 out of 319 isolates had an allelic cgMLST difference of ≤3 to another, including 91 (59.6%) ST1299. Occupancy data identified shared rooms (3.7%), shared departments (6.2%), and VRE-colonized prior room occupants (0.6%) within 30 days before diagnosis as solid epidemiological links. A new emerging VREfm clone, ST1299/CT1903/vanA, dominated our institution in 2020 and has been an important driver of the increasing VREfm rates.

Molecular characterization of tetracycline and vancomycin-resistant Enterococcus faecium isolates from healthy dogs in Egypt: a public health threat

BackgroundVancomycin-resistant enterococci (VRE) are among the most common causative pathogens for nosocomial infections worldwide. Moreover, strains of VRE have been isolated from several domestic livestock in Egypt.MethodsThis study examined if healthy dogs are a potential source of VRE infection by isolating and characterizing Enterococcus faecium strains from stool samples on a morphological basis and biochemical activities. Subsequently, it was confirmed by genotypic characterization using polymerase chain reaction (PCR), followed by the detection of antibiotic resistance genes, virulence determinants, and genes contributing to enterocin production by PCR. Furthermore, the phylogenetic relationships among vanB and tetL genes were analyzed.ResultsAll ten fecal samples were identified as E. faecium and confirmed by PCR. In addition, 90% of the isolates tested were positive for the virulence genes gelE and esp, and all the isolates tested were positive for the antibiotic resistance genes tetL and vanB. Only three of the five enterocin genes examined were detected. Ent As-48, bacteriocin 31, and Ent L50 were identified in 100%, 80%, and 60% of the samples, respectively.ConclusionDogs should be regarded as a reservoir of E. faecium that carries vancomycin resistance and virulence determinants that may affect public health in Egypt, considering a "One Health" task force approach to restrict their spread.

Increasing trend of healthcare-associated infections due to vancomycin-resistant Enterococcus faecium (VRE-fm) paralleling escalating community-acquired VRE-fm infections in a medical center implementing strict contact precautions: An epidemiologic and pathogenic genotype analysis and its implications.

To clarify whether there were clandestine intra-hospital spreads of vancomycin-resistant Enterococcus faecium (VRE-fm) isolates that led to specific strain of VRE lingering in the hospital and/or developing outbreaks that rendered a progressively increasing trend of healthcare-associated infections due to VRE-fm (VRE-fm-HAIs). Despite implementing strict contact precautions for hospitalized patients with VRE-fm-infection/colonization, number of VRE-fm-HAIs in a medical centre in southern Taiwan were escalating in 2009-2019, paralleling an increasing trend of community-acquired VRE-fm- infections. We analyzed epidemiologic data and genotypes of non-duplicate VRE-fm isolates each grown from a normally sterile site of 89 patients between December 2016 and October 2018; multilocus sequence typing (MLST) and pulse-field gel electrophoresis (PFGE) typing were performed. Totally 13 sequence types (STs) were found, and the 3 leading STs were ST17 (44％), ST78 (37％), and ST18 (6％); 66 pulsotypes were generated by PFGE. Four VRE-fm isolates grouped as ST17/pulsotype S, 2 as ST17/pulsotype AS, 2 as ST17/pulsotype AU, and 3 as ST78/pulsotype V grew from clinical specimens sampled less than one week apart from patients staying at different wards/departments and/or on different floors of the hospital. Despite possible small transitory clusters of intra-hospital VRE-fm spreads, therewas no specific VRE-fm strain lingering in the hospital leading to increasing trend of VRE-fm-HAIs during the study period. Strict contact precautions were able to curb intra-hospital VRE-fm spreads, but unable to curb the increasing trend of VRE-fm-HAIs with the backdrop of progressively increasing VRE-fm-infections/colorizations in the community.

Impact of a new hospital with close to 100% single-occupancy rooms on environmental contamination and incidence of vancomycin-resistant Enterococcus faecium colonization or infection: a genomic surveillance study

Vancomycin-resistant Enterococcus faecium (VRE) is a leading cause of nosocomial infection, driven by its ability to spread between patients and persist in the hospital environment. To investigate the impact of a long-established cardiothoracic hospital moving to new premises with close to 100% single-occupancy rooms on the rates of environmentalcontamination and infection or colonization by VRE. Prospective environmental surveillance for VRE was conducted at five time-points between April and November 2019, once in the original building, and four times in the new building. Incidence rate ratios (IRRs) of VRE infection/colonization were determined for the one-year period before and after the hospital move, and compared to a nearby hospital. In the original location, the first environmental screen found 29% VRE positivity. The following four screens in the new location showed a significant reduction in positivity (1-6%; P<0.0001). The VRE infection/colonization rates were halved in the new location (IRR: 0.56; 95% confidence interval: 0.38-0.84), compared to the original location,contrasting with an increase in a nearby hospital (1.62; 1.17-2.27) over the same time-period. Genomic analysis of the environmental isolates was consistent with reduced transmission in the new hospital. The use of single-occupancy rooms was associated with reducedenvironmental contamination with VRE, and lower transmission and isolation of VRE from clinical samples. The cost-effectiveness of single-occupancy room hospitals in reducing healthcare-associated infections should be reassessed in the context of operational costs of emerging pandemic and increasing antimicrobial resistance threats.

Vancomycin-sensitive Enterococcus faecium bacteraemia - hospital transmission and mortality in a Danish University Hospital.

Introduction. The emergence of vancomycin-resistant Enterococcus faecium (VREfm) has left the vancomycin-sensitive E. faecium (VSEfm) strains almost unnoticed.Hypothesis. Molecular characteristics, hospital transmission patterns and clinical impact of VSEfm have changed, and VSEfm is a predictor of VREfm introduction.Aim. We wanted to do a molecular characterization of VSEfm to identify hospital transmissions and links between VSEfm and VREfm, and to investigate the demographics, treatment and impact on mortality of VSEfm bacteraemia.Methodology. VSEfm and VREfm blood culture isolates from Odense University Hospital, Denmark, from 2015 to 2019 were characterized using whole-genome sequencing and core-genome multilocus sequence typing (cgMLST). Clonal shifts and diversity of the VREfm isolates were compared to the VSEfm isolates. Hospital records were used for clinical data and transmission investigation of VSEfm cases.Results. Six-hundred and thirty VSEfm isolates from 599 patients belonged to 42 sequence types (STs) and 131 complex types (CTs) in several clusters. Multiple types were involved in putative transmission, occurring over the entire period. Twenty-seven VREfm bacteraemia cases were included. No correlation between the VSEfm and VREfm clones was identified. The 30 day mortality was 40 %, but only in 6.3 % of the cases, VSEfm bacteraemia was the likely cause of death.Conclusion. The molecular types of VSEfm bacteraemia isolates are changing and diverse. No direct correlation between VSEfm and the introduction of VREfm was found, but widespread hospital transmission indicates a presence of risk factors that could facilitate transmission of other micro-organisms as well. VSEfm bacteraemia is rarely the cause of death, indicating that 30 day mortality does not reflect the cause of death.

Tolerance of clinical vancomycin-resistant Enterococcus faecium isolates against UV-C light from a mobile source

BackgroundAdmission to a room previously occupied by patients carrying environmentally robust pathogens implies an increased risk of acquiring those pathogens. Therefore, ‘No-touch’ automated room disinfection systems, including devices based on UV-C irradiation, are discussed to improve terminal cleaning. It is still unclear if clinical isolates of relevant pathogens behave differently under UV-C irradiation compared to laboratory strains used in the approval process of disinfection procedures. In this study we analysed the susceptibility of well characterized clonally divergent vancomycin-resistant enterococci (VRE) strains, including a linezolid-resistant isolate, against UV-C radiation.MethodsSusceptibility against UV-C of ten clonally divergent clinical isolates of VRE was determined in comparison to the commonly used test organism Enterococcus hirae ATCC 10541. Ceramic tiles contaminated with 105 to 106 colony forming units/25 cm² of the different enterococci were positioned at a distance of 1.0 and 1.5 m and irradiated for 20 s, resulting in a UV-C dose of 50 and 22 mJ/cm², respectively. Reduction factors were calculated after quantitative culture of the bacteria recovered from treated and untreated surfaces.ResultsSusceptibility to UV-C varied considerably among the strains studied, with the mean value of the most robust strain being up to a power of ten lower compared to the most sensitive strain at both UV-C doses. The two most tolerant strains belonged to MLST sequence types ST80 and ST1283. The susceptibility of the laboratory strain E. hirae ATCC 10541 ranged between the most sensitive and most tolerant isolates for both irradiation doses. However, for UV-C dose of 22 mJ/cm², the reduction of the most tolerant isolate of ST1283 was statistically significantly lower compared to E. hirae ATCC 10541. The most susceptible strains belonged to the MLST sequence types ST117 and ST203.ConclusionsThese results indicate that UV-C doses reported in the literature are sufficient for the reduction of commonly used reference strains of enterococci but could be insufficient for the reduction of tolerant patient VRE-isolates in a hospital setting. Therefore, for future studies, the most tolerant clinical isolates should be used to validate automated UV-C devices or longer exposure times should be expected to ensure efficacy in the real world.

Occult Vancomycin-Resistant Enterococcus faecium ST117 Displaying a Highly Mutated vanB2 Operon

Rare information is available on clinical Enterococcus faecium encountered in Sardinia, Italy. This study investigated the antimicrobial susceptibility profiles and genotypic characteristics of E. faecium isolated at the University Hospital of Sassari, Italy, using the Vitek2 system and PCR, MLST, or WGS. Vitek2 revealed two VanB-type vancomycin-resistant Enterococcus faecium (VREfm) isolates (MICs mg/L = 8 and ≥32) but failed to detect vancomycin resistance in one isolate (MIC mg/L ≤ 1) despite positive genotypic confirmation of vanB gene, which proved to be vancomycin resistant by additional phenotypic methods (MICs mg/L = 8). This vanB isolate was able to increase its vancomycin MIC after exposure to vancomycin, unlike the "classic" occult vanB-carrying E. faecium, becoming detectable by Vitek 2 (MICs mg/L ≥ 32). All three E. faecium had highly mutated vanB2 operons, as part of a chromosomally integrated Tn1549 transposon, with common missense mutations in VanH and VanB2 resistance proteins and specific missense mutations in the VanW accessory protein. There were additional missense mutations in VanS, VanH, and VanB proteins in the vanB2-carrying VREfm isolates compared to Vitek2. The molecular typing revealed a polyclonal hospital-associated E. faecium population from Clade A1, and that vanB2-VREfm, and nearly half of vancomycin-susceptible E. faecium (VSEfm) analyzed, belonged to ST117. Based on core genome-MLST, ST117 strains had different clonal types (CT), excluding nosocomial transmission of specific CT. Detecting vanB2-carrying VREfm isolates by Vitek2 may be problematic, and alternative methods are needed to prevent therapeutic failure and spread.

Epidemiological profiles and pathogenicity of Vancomycin-resistant Enterococcus faecium clinical isolates in Taiwan.

The emerging Vancomycin-resistant Enterococcus faecium (VRE-fm) is an opportunistic pathogen causing nosocomial infections. The identification of VRE-fm is important for successful prevention and control in healthcare settings. VRE-fm clinical isolates obtained from regional hospitals in northern Taiwan were characterized for antimicrobial susceptibility, virulence genes and biofilm production. Most isolates exhibited multi-drug resistance and carried the virulence genes, esp and hyl. While all isolates produce biofilms, those isolates that carried esp exhibited greater biofilm production. Isolates with different virulence gene carriages were examined for pathogenicity by using a nematode model, Caenorhabditis elegans, for determining microbial-host interactions. The survival assay showed that C. elegans was susceptible to Linezolid-resistant VRE-fm isolates with hyl. Combining the molecular epidemiological profiles regarding pathogenesis in C. elegans can serve as a guide for physicians in limiting opportunistic infections caused by VRE-fm.

Genomic Characterization of a Vancomycin-Resistant Strain of Enterococcus faecium Harboring a rep2 Plasmid.

In China, vancomycin-resistant enterococci (VRE) was not a common occurrence, and research on the genetic context and transmission mechanism of vanA-plasmid was scarce. The aim of this study was to molecularly characterise a vancomycin-resistant Enterococcus faecium isolate from a bloodstream infection and determine the genetic environment and delivery pattern of the plasmid carrying vancomycin-resistant gene. In May 2022, a vancomycin-resistant strain of Enterococci was identified during routine screening for VRE bacteria at the First Affiliated Hospital, Zhejiang University School of Medicine. Utilizing matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), the isolate was accurately identified. Antimicrobial susceptibility and whole-genome sequencing (WGS) were employed to perform phenotypic and genomic analysis, respectively. Further bioinformatics analyses was carried out to characterize the vanA-bearing plasmid. The antimicrobial susceptibility test showed that SJ2 strain was resistant to multiple antimicrobials, including ampicillin, benzylpenicillin, ciprofloxacin, erythromycin, levofloxacin, streptomycin, and vancomycin. Whole-genome analysis revealed that SJ2 strain carries several antimicrobial resistance genes and virulence determinants. MLST analysis found that SJ2 strain belongs to an unknown ST type. Plasmid analysis confirmed that the vanA gene was located on a variant of ~50 kb rep2 plasmid. Our study found that vanA-bearing rep2 plasmid is a potential source of dissemination and outbreak, and continuous surveillance is necessary to control its spread in Hangzhou, China.

Multisite Detection of Tn1549-Mediated vanB Vancomycin Resistance in Multidrug-Resistant Enterococcus faecalis ST6 in Texas and Florida.

In the United States, vanB-mediated resistance in enterococci is rare. We characterized three sequence type (ST) 6, vancomycin-resistant Enterococcus faecalis isolates causing bacteremia in unique patients in spatiotemporally distinct settings. Isolates were recovered between 2018 and 2020 in two cities in the United States (Houston, TX; Miami, FL). The isolates harbored the vanB operon on a chromosomally located Tn1549 transposon, and epidemiological data suggested multiple introductions of the vanB gene cluster into ST6 E. faecalis.

Molecular epidemiology of bacteraemic vancomycin-resistant Enterococcus faecium isolates and in vitro activities of SC5005 and other comparators against these isolates collected from a medical centre in northern Taiwan, 2019-2020.

The global prevalence of vancomycin-resistant Enterococcus faecium (VREfm) highlights the need for new anti-enterococcal agents. Here, we assessed the molecular epidemiology of clinical VREfm bacteraemic isolates from a medical centre in northern Taiwan in 2019-2020 and to evaluate their susceptibility to last-line antibiotics and a new antimicrobial agent, SC5005. The molecular epidemiology of VREfm was investigated using van genotyping, MLST and PFGE. The susceptibilities of VREfm strains to antibiotics and SC5005 were determined using the agar dilution and broth microdilution methods. The capability of E. faecium to develop resistance to antibiotics and SC5005 was evaluated using frequency of resistance and multipassage resistance assays. The mode of action of SC5005 was assessed by time-kill, bacterial membrane integrity and membrane potential assays. All 262 VREfm isolates harboured vanA gene, and the most prevalent sequence type was ST17 (51%, n = 134, 84 pulsotypes), followed by ST78 (25%, n = 65, 54 pulsotypes). Additionally, we identified four new STs (ST2101, ST2102, ST2135 and ST2136) and observed the arrival of multidrug-resistant ST1885 in Taiwan. Moreover, SC5005 was effective against all VREfm isolates, including those non-susceptible to last-line antibiotics. SC5005 can disrupt and depolarize the bacterial membrane to kill E. faecium without detectable resistance. The findings provide insights into the latest epidemiology and resistance profiles of bacteraemic-causing VREfm in northern Taiwan. Additionally, SC5005 has the potential for development as a new therapeutic to treat VREfm infections.

Germany's Burden of Disease of Bloodstream Infections Due to Vancomycin-Resistant Enterococcus faecium between 2015-2020.

In Germany, there is an increasing amount of vancomycin-resistant Enterococcus faecium (VREfm) isolates in bloodstream infections (BSIs); however, estimates on recent incidences and disease burden are missing. We aim to estimate the incidence and calculate the annual disease burden in disease-adjusted life years (DALYs) for BSIs due to VREfm in Germany between 2015 and 2020 to support informed decision-making in the field of antimicrobial resistance (AMR). We used the Antibiotic Resistance Surveillance (ARS) system data to obtain incidence estimates. The estimated incidences were used in the Burden of Communicable Disease in Europe (BCoDE) toolkit to calculate the attributable DALYs. A total of 3417 VREfm blood culture-positive isolates were observed within ARS. The estimated incidence of VREfm-BSIs per 100,000 inhabitants increased from 1.4 (95% Uncertainty Interval [UI]: 0.8-1.9) in 2015 to 2.9 (95% UI: 2.4-3.3) in 2020. The estimated burden, expressed in DALYs per 100,000 inhabitants, increased from 8.5 (95% UI: 7.3-9.7; YLD = 0.9, YLL = 7.6) in 2015 to 15.6 (95% UI: 14.6-16.6; YLD = 1.6, YLL = 14) in 2020. The most affected groups within the observed period are the 65-69-year-old males with 262.9 DALYs per 100,000 inhabitants, and in the younger age groups (&lt;30 years), the under-one-year-old with 43.1 DALYs per 100,000 inhabitants and 34.5 DALYs for male and female, respectively. The increasing DALYs of BSIs due to VREfm require targeted prevention and control measures to address their unequal distribution across gender and age, especially for older hospitalized patients, neonates, and infants in Germany.