Antimicrobial Resistance in Enterococci

Background. Enterococcus spp. are opportunistic agents of community-acquired and in-hospital infections, which have been considered a threat to public health due to their antimicrobial resistance, primarily to glycopeptides, in recent years.The aim of the study is to determine the prevalence of various Enterococcus species causing infections in hospitalized patients and their antimicrobial resistance.Methods included identification by MALDI-TOF mass spectrometry and antimicrobial susceptibility testing in accordance with the EUCAST or, in their absence, CLSI guidelines.Results. Antimicrobial resistance in 1562 consecutive Enterococcus strains isolated from hospitalized patients was determined in a major medical center admitting patients from various regions of the Russian Federation in 2019. The predominance of E.faecalis and E.faecium (99.5%) was revealed; the frequency of isolation of the former was 56% higher than that of the latter. E.avium, E.casseliflavus, E.gallinarum, E.durans were isolated from 0.5% of biological samples. The highest level of resistance of enterococci was observed to erythromycin (84.8%), tetracycline (75.0%), and rifampicin (68.2%). Multidrug, as well as vancomycin resistance, prevailed in E.faecium. All E.faecium strains isolated from blood were multidrug resistant. Resistance to vancomycin in enterococci, causing bloodstream infections, was observed solely in 19.5% of E.faecium; all vancomycin-resistant isolates were also resistant to teicoplanin. Linezolid resistance was detected in 2 community-acquired strains of E.faecalis (0.1%). Rare enterococci have shown diverse patterns of antimicrobial resistance.Conclusions. E.faecalis and E.faecium prevailed among Enterococcus spp. causing infections in hospitalized patients. Multidrug resistance and vancomycin resistance were observed predominantly in E.faecium, especially in strains causing blood-stream infections. Further monitoring of the spread and antimicrobial resistance of various Enterococcus spp. in hospital and community-acquired infections is needed.

Contemporary Clinical and Molecular Epidemiology of Vancomycin-Resistant Enterococcal Bacteremia: A Prospective Multicenter Cohort Study (VENOUS I)

Background Vancomycin-resistant enterococci (VRE) are major therapeutic challenges. Prospective contemporary data characterizing the clinical and molecular epidemiology of VRE bloodstream infections (BSI) are lacking. Methods VENOUS I is a prospective observational cohort of adult patients with enterococcal BSI in 11 US hospitals. We included patients with Enterococcus faecalis or E. faecium BSI with ≥1 follow-up blood culture(s) within 7 days and availability of isolate(s) for further characterization. The primary study outcome was in-hospital mortality. Secondary outcomes were mortality at days 4, 7, 10, 12, and 15 after index blood culture. A desirability of outcome ranking was constructed to assess the association of vancomycin resistance with outcomes. All index isolates were subjected to whole genome sequencing. Results 42 of 232 (18%) patients died in hospital and 39 (17%) exhibited microbiological failure (lack of clearance in the first 4 days). Neutropenia (HR 3.13), microbiological failure (HR 2.15), VRE BSI (HR 2), use of urinary catheter (HR 1.85), and Pitt BSI score ≥2 (HR 1.83) were significant predictors of in-hospital mortality. Microbiological failure was the strongest predictor of in-hospital mortality in patients with E. faecium bacteremia (HR 5.03). The impact of vancomycin resistance on mortality in our cohort changed throughout the course of hospitalization. E. faecalis ST6 was a predominant multidrug-resistant lineage, whereas a heterogeneous genomic population of E. faecium was identified. Conclusions Failure of early eradication of VRE from the bloodstream is a major factor associated with poor outcomes.

Rapid detection of Enterococcus and vancomycin resistance using recombinase polymerase amplification

Vancomycin-resistant enterococci (VRE), especially Enterococcus faecium, have been a global concern, often causing serious healthcare-associated infections. We established a rapid approach for detecting E. faecium and vancomycin-resistance genes (vanA and vanB) in clinical samples using isothermal recombinase polymerase amplification (RPA) combined with a lateral-flow (LF) strip. Specific RPA primer sets and probes for ddl (to identify the presence of E. faecium) vanA and vanB genes were designed. The RPA reaction was performed under isothermal condition at 37 °C within 20 min and read using the LF strip within a further 5 min. A total of 141 positive blood-cultures and 136 stool/rectal swab samples were tested using RPA-LF method compared to the conventional PCR method. The RPA-LF method exhibited 100% sensitivity in both blood-culture (60 E. faecium; 35 vanA type and two vanB type) and stool/rectal-swab samples (63 E. faecium and 36 vanA type) without cross-reaction (100% specificity). The lower detection limit of the RPA-LF was approximately 10 times better than that of the conventional PCR method. The RPA-LF method is an alternative rapid method with excellent sensitivity and specificity for detecting E. faecium, vanA, and vanB, and it has the potential to be used as a point-of-care device for VRE therapy and prevention.

Regulation of Resistance in Vancomycin-Resistant Enterococci: The VanRS Two-Component System

Vancomycin-resistant enterococci (VRE) are a serious threat to human health, with few treatment options being available. New therapeutics are urgently needed to relieve the health and economic burdens presented by VRE. A potential target for new therapeutics is the VanRS two-component system, which regulates the expression of vancomycin resistance in VRE. VanS is a sensor histidine kinase that detects vancomycin and in turn activates VanR; VanR is a response regulator that, when activated, directs expression of vancomycin-resistance genes. This review of VanRS examines how the expression of vancomycin resistance is regulated, and provides an update on one of the field’s most pressing questions: How does VanS sense vancomycin?

Comparison of Different Phenotypic Methods for Detection of Vancomycin Drug Resistance in Enterococcus Species

Introduction: Vancomycin resistant enterococci have emerged as an important cause of nosocomial infection worldwide. Vancomycin drug resistance needs to be detected accurately in all Enterococcus species in order to prevent its spread in health care setting. Present study was conducted to compare three different phenotypic methods for detection of vancomycin resistance in enterococci. Material and methods: Study was conducted in a tertiary care hospital over a period of one year. Enterococcus species isolated from clinical samples like urine, pus, blood and sterile body fluids were tested by three different methods namely disk diffusion, E-strip and Phoenix automated system for detection of vancomycin resistance. Results: 400 Enterococcus species were isolated from clinical samples. 19(4.8%) Enterococcus species were found to be vancomycin resistant and one (0.25%) strain was found to be intermediate resistant to vancomycin by all three methods resulting in 100% sensitivity and 100%specificity. Conclusion: Present study recommends vancomycin disk diffusion as screening and E-strip as good confirmatory tests in resource poor settings for detection of vancomycin drug resistance. Keywords: VRE, vancomycin, disk diffusion, E strip, Phoenix automated system..

The Vancomycin Resistance-Associated Regulatory System VraSR Modulates Biofilm Formation of Staphylococcus epidermidis in an ica -Dependent Manner

S. epidermidis is a leading cause of hospital-acquired catheter-related infections, and its pathogenicity depends mostly on its ability to form biofilms on implants. The biofilm formation is a complex procedure that involves multiple regulating factors. Here, we show that a vancomycin resistance-associated two-component regulatory system, VraSR, plays an important role in modulating S. epidermidis biofilm formation and tolerance to stress.

Identification of Vancomycin Resistance Determinants in Twin Cities of Rawalpindi/Islamabad

Vancomycin resistant Enterococci have emerged rapidly in the recent years leading to treatment failure. The aim of this work was to identify vancomycin resistance determinants; vanA and vanB genes in Enterococci. The blood, urine and throat samples were collected from 150 patients from local hospitals of twin cities of Rawalpindi/Islamabad. Forty-nine phenotypically confirmed isolates were further confirmed by PCR amplification for vancomycin determinants (genes for vanA and vanB) for vancomycin resistant Enterococci. Dependence and frequency distribution of VRE and VSE bacteraemia with respect to age, gender and source was also studied. Phenotypically resistant strains were positive for vanA while negative for vanB. vancomycin susceptible enterococci (VSE) could be isolated more from urine samples as compared to blood whereas vancomycin resistant enterococci (VRE) was found more prevalent in the blood samples (p value= 0.000). VRE was more frequently isolated from patients aged 50 or above whereas VSE prevalence was same in both age groups (p value=0.002). Gender was not found to have any significant impact on VRE or VSE bacteraemia. This study reports vanA gene cluster responsible for resistance in Pakistani population and frequently isolation of VRE from blood samples. Keywords: Enterococcus, Vancomycin resistant Enterococci, Pakistan