Vancomycin-susceptible Enterococcus Research Articles

Comparison of antibiotic resistance and virulence in vancomycin-susceptible and vancomycin-resistant Enterococcus faecium strains

Aim. Today, infections caused by vancomycin-resistant Enterococcus faecium (VRE) are a major problem in the healthcare system. The aim of this study was to compare the antibiotic resistance and virulence traits between vancomycin-susceptible E. faecium (VSE) and VRE clinical isolates.Material and Methods. Studies were performed on 66 E. faecium (32 VRE and 34 VSE) strains. Susceptibility testing and identification were performed, and strains were examined for ß-lactamase, hemolysin and biofilm production. Isolates were tested for the presence of 5 van genes, 8 virulence genes and 6 aminoglycoside-modifying enzyme (AME) genes. Obtained amplicons were subjected to electrophoretical separation and DNA sequencing.Results. Among 32 VRE isolates, 28 were found to have the VanA phenotype, and 4 the VanB. The most frequent resistance and virulence profile among VRE strains was resistance to ampicillin, imipenem, gentamicin, streptomycin, teicoplanin, and vancomycin with enterococcal surface protein (esp), endocarditis antigen (efaA), collagen adhesin (acm), and hialuronidase (hyl) genes; among VSE: resistance to ampicillin, imipenem, gentamicin, streptomycin with esp, efaA, acm, and hyl genes. Conclusions. Our findings prove that both VRE and VSE strains were well equipped with virulence and resistance genes, although VRE strains were characterized by a greater variety and a higher number of these genes. However, statistical analysis revealed no significant differences between VSE and VRE strains (p > 0.05). Nevertheless, our results suggest that VRE strains may slowly acquire and incorporate resistance and virulence genes, due to their ability to survive in a hospital environment for a long time.

2428. Lower Rates of Antibiotic Treatment of Vancomycin-Resistant Compared With Vancomycin Susceptible Enterococcal Bacteriuria

BackgroundAccording to the IDSA guidelines, most asymptomatic bacteriuria should not be treated. The identification of drug resistance often leads to inappropriate antibiotic prescribing. We evaluated prescribing patterns of vancomycin-resistant enterococci (VRE) and vancomycin-susceptible enterococci (VSE) at a regional health system to determine whether the rates differ by institution.MethodsThis is a retrospective chart review of all adult inpatients at the St. John Providence Health System (SJPHS) with positive urine culture identified as VRE or VSE between April 1, 2017 and October 1, 2017. The groups were matched to hospital location, age within 5 years and gender. Patients with medical records that were not available were excluded. Patient demographics (age, sex), location of patient (institution), ID consult, fever, treatment, antibiotic class and the duration of treatment was collected. Bacteriuria was defined as a UTI if there was fever or enterococcal bacteremia. We evaluated frequency of treatment as well as type and duration of antibiotics.Results208 patients with VRE bacteriuria at SJPHS were identified and 106 met our inclusion criteria. 1,304 of VSE bacteriuria at SJPHS were identified and 106 were matched. The mean age was 70.4 and 71.3 (P = 0.476) in the VRE and VSE groups respectively and each group had 35.8% males. The table below depicts the number of patients with VRE/VSE being treated by institution.SiteIncludedID ConsultNumber TreatedFever(+) BCxMedian length of Rx (days)Hospital 122/2220/145/48/42/27/14.5Hospital 247/4740/2715/218/50/07/7Hospital 35/54/31/22/00/07/13Hospital 422/2216/135/123/30/17/7Hospital 510/109/54/62/30/06.5/8.5Total106/10689/62 (P < 0.0001)30/45 (P = 0.0085)23/15 (P = 0.21)2/37/7Therapy for VRE was diverse among most institutions and included agents such as daptomycin, β-lactams, doxycycline, fosfomycin, nitrofurantoin and linezolid. Hospital 2 had a total of 15 treated cases; 11 of which were treated with linezolid. Therapy for VSE primarily consisted of β-lactam or vancomycin.ConclusionThe rates of treatment were higher with VSE compared with VRE. ID was more frequently consulted in patients with VRE and those patients were treated less frequently.Disclosures All authors: No reported disclosures.

Prevalence of vancomycin-variable Enterococcus faecium (VVE) among vanA-positive sterile site isolates and patient factors associated with VVE bacteremia.

Vancomycin-variable enterococci (VVE) are vanA-positive, vancomycin-susceptible enterococci with the ability to revert to a vancomycin-resistant phenotype on exposure to vancomycin. We sought to assess the prevalence of VVE and to determine clinical characteristics of patients infected with VVE. We prospectively collected Enterococcus faecium sterile site isolates from Toronto Invasive Bacterial Diseases Network hospitals from January 2015 to June 2016 and calculated VVE (defined as vanA-positive, vancomycin-susceptible isolates) prevalence among vanA-containing isolates. We performed chart reviews of VVE and vancomycin-resistant E. faecium (VRE) bacteremias identified from January 2012 to June 2016, and on a random sample of patients with bacteremia due to vanA/vanB-negative, vancomycin-susceptible enterococci (VSE) from January 2015 to June 2016. Clinical characteristics were compared and factors associated with mortality assessed. Because of the potential reversion from VVE to VRE, pulsed-field gel electrophoresis (PFGE) was performed for strains causing breakthrough bacteremia in order to identify relatedness among strains with different phenotypic resistance within the same patient. VVE comprised 47% (18/38) of vanA-positive isolates. The charts of 36 VRE, 25 VVE, and 79 VSE patients were reviewed. Central venous catheter associated bacteremia was more common in VVE (44%) and VRE patients (57%) than in VSE patients (28%) (P = 0.01). The Pitt bacteremia (OR 1.3, P = 0.002) and the Charlson score (OR 1.2, P = 0.008) were the only independent mortality predictors. PFGE of strains causing breakthrough bacteremia showed high within-patient clonality, irrespective of vanA-positivity or vancomycin-susceptibility. A substantial proportion of vanA-positive isolates are VVE and are therefore not detected with conventional selective culture methods. Bacteremia sources of patients with VVE are similar to those infected with VRE. We detected no association between VVE and 30-day mortality or breakthrough bacteremia.

In vitro activity of oritavancin against planktonic and biofilm states of vancomycin-susceptible and vancomycin-resistant enterococci

We tested the in vitro activity of oritavancin against 60 vancomycin-susceptible enterococci (VSE) and 27 vancomycin-resistant enterococci (VRE). The oritavancin MIC ranged from ≤0.002 to 0.5μg/mL; the minimum biofilm bactericidal concentration ranged from ≤0.002 to 2μg/mL. Oritavancin has promising in vitro activity against VSE and VRE in both planktonic and biofilm states.

Economic burden of nosocomial infections caused by vancomycin-resistant enterococci

BackgroundNosocomial infections due to vancomycin-resistant enterococci (VRE) have become a major problem during the last years. The purpose of this study was to investigate the economic burden of nosocomial VRE infections in a European university hospital.MethodsA retrospective matched case-control study was performed including patients who acquired nosocomial infection with either VRE or vancomycin-susceptible enterococci (VSE) within a time period of 3 years. 42 cases with VRE infections and 42 controls with VSE infections were matched for age, gender, admission and discharge within the same year, time at risk for infection, Charlson comorbidity index (±1), stay on intensive care units and non-intensive care units as well as for the type of infection, using criteria of the Centers for Disease Control and Prevention.ResultsThe median overall costs per case were significantly higher than for controls (EUR 57,675 vs. EUR 38,344; p = 0.030). Costs were similar between cases and controls before onset of infection (EUR 17,893 vs. EUR 16,600; p = 0.386), but higher after onset of infection (EUR 37,971 vs. EUR 23,025; p = 0.049). The median attributable costs per case for vancomycin-resistance were EUR 13,157 (p = 0.036). The most significant differences in costs between cases and controls turned out to be for pharmaceuticals (EUR 6030 vs. EUR 2801; p = 0.008) followed by nursing staff (EUR 8956 vs. EUR 4621; p = 0.032), medical products (EUR 3312 vs. EUR 1838; p = 0.020), and for assistant medical technicians (EUR 3766 vs. EUR 2474; p = 0.023). Furthermore, multivariate analysis revealed that costs were driven independently by vancomycin-resistance (1.4 fold; p = 0.034).ConclusionsThis analysis suggested that nosocomial VRE infections significantly increases hospital costs compared with VSE infections. Therefore, hospital personal should implement control measures to prevent VRE transmission.

Detection of vancomycin-resistant enterococci using chromogenic selective medium

Objective. To detect vancomycin-resistant enterococci (VRE) using chromogenic selective medium CHROMagar™VRE (CHROMagar, France). Materials and Methods. In the first part of the study, a total of 39 vancomycin-resistant and 20 vancomycinsusceptible Enterococcus spp. isolated from blood culture with known susceptibility profiles were incubated on the CHROMagar™VRE (CHROMagar, France) and examined after 24 h and 48 h of incubation. In the second part of the study, a total of 110 rectal swabs were taken from patients with hematological malignancies and incubated on the CHROMagar™VRE. The vancomycin susceptibility of isolates grown on the selective medium was further evaluated by the broth microdilution method (CLSI, 2017). Glycopeptide resistance genes were detected by PCR. Results. Using the CHROMagar™VRE, a total of 36 (92.3%) vancomycin-resistant isolates were detected after 24 h and additional two isolates – after 48 h of incubation. The sensitivity of the selective medium for detection of VRE obtained from blood culture was 92% and 97% after 24 h and 48 h of incubation, respectively. All 20 vancomycin-susceptible enterococci did not grow on the CHROMagar™VRE (specificity – 100%). Of 110 rectal swabs, 35 (31.8%) samples were positive for Enterococcus spp. on the CHROMagar™VRE (33 – E. faecium и 2 – E. faecalis). Resistance to vancomycin was detected in 32⁄33 (97%) E. faecium isolates, of them 28 and 4 strains were isolated after 24 h and 48 h of incubation; all VRE strains carried vanA gene. The proportion of false positive isolates was 3.4% after 24 h of incubation and 8.6% after 48 h of incubation on the CHROMagar™VRE medium for screening of VRE from rectal swabs. Conclusions. The chromogenic selective media CHROMagar™VRE has a high sensitivity and specificity for the detection of VRE and can be used for screening in laboratory practice.

Dalbavancin is active in vitro against biofilms formed by dalbavancin-susceptible enterococci

We tested the in vitro activity of dalbavancin, vancomycin and daptomycin against 83 enterococcal isolates in planktonic and biofilm states. The MIC90 for vancomycin-susceptible Enterococcus faecalis was 0.125 and 4μg/mL for dalbavancin and daptomycin, respectively. For vancomycin-resistant Enterococcus faecium, the MIC90 was >16 and 2μg/mL for dalbavancin and daptomycin, respectively. Dalbavancin minimum biofilm inhibitory concentrations (MBICs) for vancomycin-susceptible and -resistant isolates were ≤0.25 and >16μg/mL, respectively. The daptomycin MBIC90 for all isolates was 4μg/mL. For E. faecalis and E. faecium, dalbavancin minimum biofilm bactericidal concentrations (MBBCs) for vancomycin-susceptible and -resistant isolates were ≤4 and >16μg/mL, respectively, whereas vancomycin MBBCs were >128μg/mL for all isolates, and daptomycin MBBC90 values for both species were 128μg/mL. In summary, dalbavancin exhibited in vitro activity against all tested isolates of vancomycin-susceptible, but not against vancomycin-resistant enterococci; activity was observed in both the planktonic and biofilm states.

In Vitro Activity of Telavancin Against Clinically Important Gram-Positive Pathogens from 69 U.S. Medical Centers (2015): Potency Analysis by U.S. Census Divisions.

A total of 8,072 gram-positive isolates collected from 69 medical centers among all 9 U.S. Census Divisions during the 2015 SENTRY Antimicrobial Surveillance Program were included. Telavancin had minimal inhibitory concentration (MIC)50 and MIC90 values of 0.03/0.06 μg/mL, respectively, against methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). Similar activity was also observed among coagulase-negative staphylococci (MIC50/90, 0.03/0.06 μg/ml; 100.0% inhibited by ≤0.12 μg/ml). Telavancin was active against vancomycin-susceptible Enterococcus faecalis (MIC50/90, 0.12/0.12 μg/ml) and Enterococcus faecium (MIC50/90, 0.03/0.06 μg/ml), but was less active against vancomycin-resistant E. faecium (MIC90, >2 μg/ml) and E. faecalis (MIC90, >2 μg/ml). Streptococci showed modal MIC results of 0.008 μg/ml (Streptococcus pneumoniae) to 0.015 μg/ml (β-hemolytic streptococci and viridans group streptococci). Potency variations for telavancin within Census Divisions were not observed. Telavancin remains potent in vitro against indicated pathogens recovered from U.S. medical centers (2015).

Frequency of antiseptic resistance genes in clinical staphycocci and enterococci isolates in Turkey

BackgroundDisinfectants and antiseptics are biocides widely used in hospitals to prevent spread of pathogens. It has been reported that antiseptic resistance genes, qac’s, caused tolerance to a variety of biocidal agents, such as benzalkonium chloride (BAC) and chlorhexidine digluconate (CHDG) in Staphylococcus spp. isolates. We aimed to search the frequency of antiseptic resistance genes in clinical Staphylococcus spp. and Enterococcus spp. isolates to investigate the possible association with antiseptic tolerance and antibiotic resistance.MethodsAntiseptic resistance genes (qacA/B, smr, qacG, qacH, and qacJ) isolated from Gram-positive cocci (69 Staphylococcus spp. and 69 Enterococcus spp.) were analyzed by PCR method. The minimum inhibitory concentrations (MICs) of BAC and CHDG were determined by agar dilution method, whereas antibiotic susceptibility was analyzed by disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI) criteria.ResultsThe frequency of antiseptic resistance genes was found to be high (49/69; 71.0%) in our clinical staphylococci isolates but absent (0/69; 0%) in enterococci isolates. The frequency of qacA/B and smr genes was higher (25/40; 62.5% and 7/40; 17.5%, respectively) in coagulase negative staphylococci (CNS) when compared to Staphylococcus aureus strains (3/29; 10.3%, and 4/29; 13.8%, respectively). In contrast, the frequency of qacG and qacJ genes was higher (11/29; 37.9% and 8/29; 27.5%, respectively) in S. aureus than those of CNS (5/40; 12.5%, 10/40; 25.0%) strains. qacH was not identified in none of the strains. We found an association between presence of antiseptic resistance genes and increased MIC values of BAC (>4 μg/mL) in staphylococci and it was found to be statistically statistically significant (p < 0.01). We also showed that MICs of BAC and CHDG of vancomycin-resistant enterococci (VRE) isolates were significantly higher than those of vancomycin-susceptible enterococci (VSE) isolates (p < 0.01).ConclusionsFor our knowledge, our study is the first to investigate antiseptic resistance genes in enterococci and also qacG, qacH, and qacJ genes in staphylococci isolates in Turkey. Further studies are needed to revise the biocide policy and to support infection control programs to avoid the development of new resistance mechanisms.

Telavancin activity in vitro tested against a worldwide collection of Gram-positive clinical isolates (2014).

Telavancin activity was measured against Gram-positive pathogens collected worldwide during 2014 using the revised broth microdilution testing method. The results were compared with previous reports. A total of 10552 isolates from 86 sites located in 32 countries were included as part of the Telavancin International Surveillance Program for the Americas, Europe and Asia-Pacific. Telavancin had MIC50 and MIC90 values of 0.03μg/mL and 0.06μg/mL, respectively, against Staphylococcus aureus, regardless of methicillin susceptibility, and inhibited all S. aureus isolates at the CLSI breakpoint (≤0.12μg/mL). Telavancin was eight-fold more active than daptomycin (MIC50/90, 0.25/0.5μg/mL) and 16-32-fold more active than vancomycin (MIC50/90, 1/1μg/mL) and linezolid (MIC50/90, 1/1μg/mL) against methicillin-resistant S. aureus (MRSA). Telavancin was also active against coagulase-negative staphylococci isolates (MIC50/90, 0.06/0.06μg/mL). Vancomycin-susceptible Enterococcus faecalis isolates (n=718) were all inhibited by telavancin (MIC50/90, 0.12/0.12μg/mL) at ≤0.25μg/mL (CLSI breakpoint), except for a single isolate (MIC, 0.5μg/mL). All Enterococcus faecium and E. faecalis isolates with telavancin MICs of ≥0.5μg/mL and ≥1μg/mL, respectively, had a VanA phenotype. Based on the MIC90 values, telavancin was at least eight-fold more potent than comparators against vancomycin-susceptible enterococci. With the exception of Streptococcus agalactiae (MIC50, 0.03μg/mL), all tested species of streptococci exhibited telavancin MIC50 values of ≤0.015μg/mL. These in vitro results from 2014 highlight the potent in vitro activity of telavancin and demonstrate that its activity was virtually unchanged compared with the corresponding 2013 telavancin surveillance results.

Rapid Phenotypic Detection of Microbial Resistance in Gram-Positive Bacteria by a Real-Time Laser Scattering Method.

We developed a methodology for antimicrobial susceptibility testing (AST) based on the BacterioScanTM216R laser scattering technology, using methicillin resistance in Staphylococcus aureus and vancomycin resistance in enterococci as exemplar for important resistance phenotypes. Fifty methicillin-resistant (MRSA) and 50 methicillin-susceptible (MSSA) S. aureus, as well as 50 vancomycin-resistant enterococci (VRE) and 50 vancomycin-susceptible enterococci (VSE) isolates were used for the study. Optimal test conditions were derived by investigating the effects of inoculum size, medium, incubation temperature and broth filtration. We proposed four different statistical approaches for rapid discrimination between resistant and susceptible bacteria. The statistical approach based on raw measurements of bacterial concentrations delivered sensitivity of 100% and specificity of 94% for discrimination between MRSA and MSSA already after 3 hours of incubation. Categorical agreement of ≥90% was achieved after 140 min with this approach. Differentiation between VRE and VSE was possible with 98% sensitivity and 92% specificity after 3 hours, using a sophisticated statistical approach based on concentration slopes derived from the raw concentration measurements. This approach provided categorical agreement of ≥90% after 165 min. The sensitivity and specificity estimates were confirmed by leave-one-out cross validation. In conclusion, the phenotypic AST methods developed in this study are promising for rapid detection of MRSA and VRE. The development and application of this technology would allow early detection of the resistant pathogens, thus facilitating swift change to the targeted antimicrobial treatment as well as timely initiation of appropriate infection control measures. Further studies are warranted to validate this approach for the detection of other resistance phenotypes, including direct testing from clinical specimens.

One Year Incidence of Infection in Intestine Transplant Recipients at a Single Center

Introduction: This study reports the infection rate, location of infection, and pathogen causing bacterial, fungal, or viral infections in intestine transplant recipients during the first year post-transplant at an active transplant center. Additional risk for infection was assessed based on simultaneous inclusion of the liver or colon as a part of the intestine transplant. Methods: Records from a single transplant center were reviewed for patients receiving an intestine transplant. Positive cultures and pathology reports were used to diagnose bacterial, fungal, and viral infections and also to determine location and infectious agent. For analysis, patients were grouped by age (pediatric or adult). Results: During the study period, 236 intestine transplants were performed, 184 adults and 52 pediatric patients. In adults, one year bacterial, fungal, and viral infection rates were 91%, 47%, and 29%, respectively. The most commonly infected sites were the urinary tract and bloodstream. Coagulase-negative Staphylococcus was the most commonly isolated pathogen and found in 48% of patients. Candida species were the most common fungal pathogens and seen in 42% of all patients, and in 89% of patients who developed a fungal infection. Cytomegalovirus infections were present in 15% of transplant recipients. Bacterial and fungal bloodstream infections (BSI) developed in 72% of patients with a median time to first infection of 30 days. Among pediatric patients, bacterial, fungal, and viral infection rates were 90%, 25%, and 75%, respectively. Vancomycin susceptible enterococci were the most common pathogens and isolated from 52% of patients. Candida species were the most common fungal pathogens and observed in 23% of patients. Upper respiratory viral infections were common (44%) and cytomegalovirus infection rate was 17%. The most common sites of infection were bloodstream, urinary, and upper respiratory tract. The median days to the first BSI was 38 days. Conclusion: Overall, 91% of adult and 90% of pediatric intestine transplant patients had a bacterial infection in the first year post-transplant. Opportunistic fungal and viral infections were also common. Age, gender, race, or liver inclusion did not have a significant impact on the development of a BSI or median time to first BSI. Colon inclusion significantly (p < .05) decreased the risk of developing a BSI in pediatric patients, while not having a significant impact on median days to first BSI or development of a BSI in adults. The two tables below represent a portion of the data analyzed.FigureFigure

Genotyping, antimicrobial resistance and virulence factor gene profiles of vancomycin resistance Enterococcus faecalis isolated from blood culture.

Enterococcus spp. is the common of intestinal micro flora in humans but nowadays this gram-positive bacterium causes the variety of nosocomial infections. Resistance to antibiotic and also, presence of different virulence genes in the enterococcus spp. can change it to problematic microorganisms in the health care centers. The aim of this study was determined the genotyping, antimicrobial resistance and virulence factor gene profiles of vancomycin resistance Enterococcus faecalis isolated from blood culture. In this study, enterococcus isolated from BACTEC was collected and antibiotic susceptibility testing was done according to CLSI recommendation. Important virulence genes and vancomyci resistance genes were detected by PCR and molecular typing was performed by RAPD PCR assay. Nine enterococcus collected from 194 positive BACTEC and seven out of nine were vancomycin-resistant enterococcus (VRE). vanA gene observed in all VRE and none of strains carried vanB and vanC genes. efbaA and gelE virulence factors have been detected in all strains. ace, esp, and cyl virulence factors genes harbored in two, seven and eight isolates respectively. asaI was not detected in any strains. All seven VRE isolates were related to the one specific molecular type and two different molecular types observed in the two vancomycin susceptible enterococci according to molecular epidemiology results. More prevalence of the VRE in enterococcus isolated from BACTEC is so important and on the other hand high genetic relationship in the isolated VRE can be very considerable for nosocomial infection committee in the hospital.

In vitro activity of Oritavancin against gram-positive pathogens isolated in Canadian hospital laboratories from 2011 to 2015

Gram-positive bacterial pathogens isolated from patient specimens submitted to 15 Canadian hospital laboratories from 2011 to 2015 were tested in the coordinating laboratory for susceptibility to oritavancin and comparative antimicrobial agents using the Clinical and Laboratory Standards Institute M07-A10 (2015) broth microdilution method. Oritavancin's in vitro activity was equivalent to, or more potent than, vancomycin, daptomycin, linezolid, and tigecycline against methicillin-susceptible Staphylococcus aureus (n=2680; oritavancin MIC90, 0.12μg/mL; 99.9% oritavancin-susceptible), methicillin-resistant S. aureus (n=728; oritavancin MIC90, 0.12μg/mL; 99.7% oritavancin-susceptible), Streptococcus pyogenes (n=218; oritavancin MIC90, 0.25μg/mL; 100% oritavancin-susceptible), Streptococcus agalactiae (n=269; oritavancin MIC90, 0.12μg/mL; 100% oritavancin-susceptible), and vancomycin-susceptible Enterococcus faecalis (n=508; oritavancin MIC90, 0.06μg/mL; 100% oritavancin-susceptible). Oritavancin, dalbavancin, and telavancin demonstrated equivalent in vitro activities (MIC90, μg/mL) against 602 isolates of MSSA (0.06, 0.06, 0.06, respectively) and 144 isolates of MRSA (0.12, 0.06, 0.06, respectively) collected in 2015.

Antimicrobial, cytotoxic effect and purification of bacteriocin from vancomycin susceptible Enterococcus faecalis and its safety evaluation for probiotization

A vancomycin susceptible Enterococus faecalis CV7 produced bacteriocin was purified by size exclusion chromatography followed by RP-HPLC C-18 column. Tricine-SDS PAGE unrevealed molecular mass was further confirmed by MALDI-TOF MS as 4.829 kDa. This bacteriocin showed broad spectrum of anti-bacterial activity against important food borne pathogens mainly against Salmonella typhi and this activity also found to be withstood after treatment with different proteolytic enzymes, temperature, pH, solvents and detergents. Cytotoxicity of bacteriocin CV7 by MTT assay showed that lower survival inhibition on HeLa than HT-29 cell line at lower concentrations conclude its potentiality in food biopreservation. Results obtained from PCR amplifications revealed that strain E. faecalis CV7 does not harbor virulence genes esp, ace, cylB, cylA and efaAfs but contains asa1. With this, surviving in the presence of low pH and bile oxgall promising its safety as probiont to control Salmonella infections.

Comparison of two chromogenic media for the detection of vancomycin-resistant enterococcal carriage by nursing home residents

We compared ChromID VRE and Brilliance VRE media for the detection of vancomycin-resistant enterococci (VRE). Using a panel of 28 enterococcal isolates, 10 vanA Enterococcus faecium and three vanA Enterococcus faecalis isolates grew as per manufacturers’ instructions whilst growth of two vanC and eight vancomycin-susceptible enterococci was inhibited on both media. Important differences were noted in the selectivity and chromogenic properties of the two media for vanA Enterococcus raffinosus and vanB E. faecium. The two media were further evaluated using 295 stool samples from nursing home residents, 34 of which grew VRE (11.5%). ChromID and Brilliance had comparable sensitivity, which was increased markedly by prolonging incubation to 48 hours (from 29% to 82%, and from 41% to 85%, respectively) and by a pre-enrichment step (to 97% and 100%, respectively). Brilliance VRE agar had higher selectivity at 48 hours, and after pre-enrichment.

Telavancin activity tested against Gram-positive clinical isolates from European, Russian and Israeli hospitals (2011–2013) using a revised broth microdilution testing method: redefining the baseline activity of telavancin

Objectives: To reassess the activity of telavancin when tested against Gram-positive clinical pathogens recovered from hospitalized patients in European and adjacent regions using a revised broth microdilution method.Methods: 11 601 consecutive, non-duplicate isolates originating from 36 institutions among 18 countries recovered between 2011 and 2013 were tested for susceptibility using a revised broth microdilution method for telavancin. Interpretive telavancin breakpoints appropriate for the method were those recently approved by the FDA and EUCAST, as available.Results: Telavancin (MIC50/90, 0.03/0.06 mg/l; 100.0% susceptible) was equally potent against methicillin-susceptible ((MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus. All Enterococcus faecalis was susceptible to telavancin (MIC50/90, 0.12/0.12 mg/l) and inhibited at the susceptibility breakpoint (i.e. ≤ 0.25 mg/l), except for VanA-phenotype vancomycin-resistant isolates (telavancin MIC, >1 mg/l). Telavancin ( ≤ 0.015/0.03 mg/l) was active against vancomycin-susceptible Enterococcus faecium, while higher MIC values were obtained for VanA strains. Telavancin (both MIC50 and MIC90, ≤ 0.015 mg/l) was potent against Streptococcus pneumoniae, beta-haemolytic streptococci (MIC50/90, ≤ 0.015/0.06 mg/l) and viridans group streptococci (MIC50/90, ≤ 0.015/0.03 mg/l).Conclusions: Telavancin exhibited potent activity against this contemporary (2011–2013) collection of organisms, inhibiting indicated pathogens at or below the FDA/EUCAST-approved breakpoints for susceptibility. VanA-phenotype enterococci were less susceptible to telavancin, a feature observed using the previous testing method. These results redefine telavancin's activity against isolates from Europe.

Occurrence of vancomycin-resistant and -susceptible Enterococcus spp. in reclaimed water used for spray irrigation

Reclaiming municipal wastewater for agricultural, environmental, and industrial purposes is increasing in the United States to combat dwindling freshwater supplies. However, there is a lack of data regarding the microbial quality of reclaimed water. In particular, no previous studies have evaluated the occurrence of vancomycin-resistant enterococci (VRE) in reclaimed water used at spray irrigation sites in the United States. To address this knowledge gap, we investigated the occurrence, concentration, and antimicrobial resistance patterns of VRE and vancomycin-susceptible enterococci at three U.S. spray irrigation sites that use reclaimed water. We collected 48 reclaimed water samples from one Mid-Atlantic and two Midwest spray irrigation sites, as well as their respective wastewater treatment plants, in 2009 and 2010. Samples were analyzed for total enterococci and VRE using standard membrane filtration. Isolates were purified and then confirmed using biochemical tests and PCR. Antimicrobial susceptibility testing was conducted using the Sensititre® microbroth dilution system. Data were analyzed by two-sample proportion tests and one-way analysis of variance. We detected total enterococci and VRE in 71% (34/48) and 4% (2/48) of reclaimed water samples, respectively. Enterococcus faecalis was the most common species identified. At the Mid-Atlantic spray irrigation site, UV radiation decreased total enterococci to undetectable levels; however, subsequent storage in an open-air pond at this site resulted in increased concentrations of enterococci. E. faecalis isolates recovered from the Mid-Atlantic spray irrigation site expressed intrinsic resistance to quinupristin/dalfopristin; however, non-E. faecalis isolates expressed resistance to quinupristin/dalfopristin (52% of isolates), vancomycin (4%), tetracycline (13%), penicillin (4%) and ciprofloxacin (17%). Our findings show that VRE are present in low numbers in reclaimed water at point-of-use at the sampled spray irrigation sites; however, resistance to other antimicrobial classes is more prevalent, particularly among non-E. faecalis isolates.

Detection of vancomycin resistance in enterococcus species isolated from clinical samples and feces of colonized patients by phenotypic and genotypic methods.

The aim of this study was to find out the clinical correlation between the presence of vancomycin-resistant genes (van A and van B) and their expression as detected by phenotypic tests in colonized patients and in clinical isolates. Enterococci were isolated from various clinical samples and also from fecal specimens of colonized patients at the time of admission, after 48 h and after 5 days of admission. Identification to species level was done using standard methods. Vancomycin susceptibility in Enterococci was detected by disc diffusion test. Minimum inhibitory concentration was determined by agar dilution method. Multiplex polymerase chain reaction (PCR) was used to detect the presence of van genes. Out of all the clinical and fecal samples processed, 12.0% isolates were either vancomycin resistant or vancomycin intermediate. Further, these isolates carried van A or van B genes as confirmed by PCR methods. Expression of van A gene was found to be more in Enterococcus faecalis (28.3%) as compared to Enterococcus faecium (25.0%) in both clinical and fecal isolates. 16.6% strains of E. faecium and 15.0% strains each of E. faecalis and Enterococcus gallinarum were found to carry van B genes. The overall prevalence of vancomycin resistant Enterococci (VRE) in colonized patients was about 9.6%. Prior administration of antibiotics had significant effect (P = 0.001) on VRE carriage. Urinary tract infection was the most common infection caused by vancomycin susceptible Enterococci (VSE), 105/214 (49.0%) and VRE, 13/36 (36.1%). There was no significant difference (P = 0.112) in the distribution of VRE and VSE in different infection types. Both clinical and fecal VRE showed maximum resistance to penicillin, ampicillin, and piperacillin. Resistance to linezolid was 2.8% in clinically isolated VRE. VRE in our study were found to be resistant to a number of commonly used antibiotics. The frequency of isolation of vancomycin resistant E. faecalis (VRE.fs), which is highly virulent, and the number of strains harboring van A gene in our hospital setup is high and needs to be addressed.

A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity.