scholarly journals Pharmacodynamics of Linezolid Plus Fosfomycin Against Vancomycin–Resistant Enterococcus faecium in a Hollow Fiber Infection Model

2021 ◽  
Vol 12 ◽  
Author(s):  
Shuaishuai Wang ◽  
Huiping Liu ◽  
Jun Mao ◽  
Yu Peng ◽  
Yisong Yan ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Galleria Mellonella ◽  
Bactericidal Effect ◽  
Hollow Fibre ◽  
Good Choice ◽  
Infection Model ◽  
Severe Infections ◽  
Vancomycin Resistant ◽  
Fosfomycin Resistance

The optimal therapy for severe infections caused by vancomycin-resistant Enterococcus faecium (VREfm) remains unclear, but the combination of linezolid and fosfomycin may be a good choice. The 24-h static-concentration time-kill study (SCTK) was used to preliminarily explore the pharmacodynamics of linezolid combined with fosfomycin against three clinical isolates. Subsequently, a hollow-fibre infection model (HFIM) was used for the first time to further investigate the pharmacodynamic activity of the co-administration regimen against selected isolates over 72 h. To further quantify the relationship between fosfomycin resistance and bacterial virulence in VREfm, the Galleria mellonella infection model and virulence genes expression experiments were also performed. The results of SCTK showed that the combination of linezolid and fosfomycin had additive effect on all strains. In the HFIM, the dosage regimen of linezolid (12 mg/L, steady-state concentration) combined with fosfomycin (8 g administered intravenously every 8 h as a 1 h infusion) not only produced a sustained bactericidal effect of 3∼4 log10 CFU/mL over 72 h, but also completely eradicated the resistant subpopulations. The expression of virulence genes was down-regulated to at least 0.222-fold in fosfomycin-resistant strains compared with baseline isolate, while survival rates of G. mellonella was increased (G. mellonella survival ≥45% at 72 h). For severe infections caused by VREfm, neither linezolid nor fosfomycin monotherapy regimens inhibited amplification of the resistant subpopulations, and the development of fosfomycin resistance was at the expense of the virulence of VREfm. The combination of linezolid with fosfomycin produced a sustained bactericidal effect and completely eradicated the resistant subpopulations. Linezolid plus Fosfomycin is a promising combination for therapy of severe infections caused by VREfm.

scholarly journals Development of in Vitro Resistance to Daptomycin in Enterococcus Faecium and Estimation of Its Fitness Cost

2020 ◽  
Author(s):  
Weiliang Zeng ◽  
Tao Chen ◽  
Qing Wu ◽  
Ye Xu ◽  
Kaihang Yu ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Resistance Mechanisms ◽  
Fitness Cost ◽  
Resistant Bacteria ◽  
Infection Model ◽  
Dynamic Resistance ◽  
Vancomycin Resistant

Abstract BackgroundDaptomycin has broad-spectrum antibacterial activity against Gram-positive pathogens, but recent studies have revealed cases where daptomycin has failed to treat multidrug-resistant bacteria, such as vancomycin-resistant Enterococcus faecium. However, the resistance evolution of E. faecium to daptomycin in vitro and fitness cost remain unclear. In this study, we sought to analyze the resistance development and mechanism of E. faecium to datomycin, and futher to investigate the relationship between daptomycin resistance and fitness cost.MethodsTo investigate the development of daptomycin resistance in E. faecium, 6 daptomycin-susceptible (DAP-S) clinical isolates, including 3 vancomycin-resistant E. faecium (VRE) and 3 vancomycin-susceptible E. faecium (VSE), were exposured to daptomycin in vitro by serial passage experiment. Then the different resistance mechanisms of daptomycin-resistant (DAP-R) mutants were analyzed by polymerase chain reaction (PCR), cytochrome C binding assay and transmission electron microscopy. Furthermore, we also estimated the changes of fitness cost among each highly DAP-R mutants by bacterial growth curve measurement, in vitro competition experiments, infection model of Galleria mellonella larvae and biofilm formation assays.ResultsIn vitro, a total of 21 DAP-R mutants with minimal inhibitory concentration (MIC) of 4 to 512 μg/mL were obtained, and these mutants carried more than one mutation of LiaFSR and YycFG system encoding genes. More positive charges were detected among highly DAP-R mutants than parent isolates, and the cell walls of SC1174-D and SC1762-D mutants were remarkly thicker than those of the parent isolates. In comparison with parent isolates, besides, the growth, competition ability and virulence were significantly reduced, while the biofilm formation capacity was markedly elevated among each highly DAP-R mutants.ConclusionsOur findings suggest that E. faecium isolates are able to rapidly acquire DAP resistance in vitro through different dynamic resistance mechanisms, which often accompany by significant fitness cost. Intriguingly, DAP and glycopeptide antibiotics may present collateral-sensitivity during E. faecium acquired DAP resistance in vitro.

scholarly journals In Vitro Antimicrobial Activity of Fosfomycin, Rifampin, Vancomycin, Daptomycin Alone and in Combination Against Vancomycin-Resistant Enterococci

2021 ◽  
Author(s):  
Wei Yu ◽  
Yiheng Jiang ◽  
Hao Xu ◽  
Li Zhang ◽  
Xuehang Jin ◽  
...  
Keyword(s):  
Virulence Genes ◽  
Therapeutic Option ◽  
Bactericidal Effect ◽  
Resistance Determinant ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant ◽  
High Level ◽  
Time Kill ◽  
Level Resistance

Abstract OBJECTIVESThe emergence of vancomycin resistant enterococci (VRE) is shortening the choices for clinical anti-infective therapy. The aim of this study was to investigate the mechanism of vancomycin resistance and evaluate the effect of fosfomycin (FM), rifampin (RIF), vancomycin (VAN), linezolid (LNZ), daptomycin (DAP) alone or in combination against VRE.METHODSEight VRE isolates were collected. A total of 18 antibiotics susceptibility tests were further done for VRE. Whole genome sequencing and bioinformatics analysis were performed. The effect of FM, RIF, VNA, LNZ, DAP alone or in combination was determined using anti-biofilm testing and the time-kill assay.RESULTSAll isolates were susceptible to LNZ and DPA. The high-level resistance determinant of VAN in these strains was due to VanA-type cassette. MLST revealed two different STs for vancomycin-resistant Enterococcus faecium (VREm) and four different STs for vancomycin-resistant E. faecalis (VREs). Virulence genes in VREs were more than VREm, especially for 4942 isolated from blood. Gene acm and uppS were only identified in VREm, while virulence genes related to cytolysin were only found in E. faecalis. Further in vitro anti-biofilm testing and time-kill assay found FM (83 mg/L) combined with DAP (20.6 mg/L) and DAP monotherapy (47.1 mg/L) showed bactericidal effect against 8 tested VRE strains at 24h. CONCLUSIONSThe high-level resistance determinant of VAN in these strains was due to VanA-type cassette. FM combined with DAP might be greater potential therapeutic option against VRE.

scholarly journals 735. Bacteriophage Therapy Improves Survival of Galleria mellonella Larvae Injected with Vancomycin-Resistant Enterococcus faecium

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S329-S329 ◽  
Author(s):  
Lynn El Haddad ◽  
Cynthia P Harb ◽  
Mark Stibich ◽  
Roy F Chemaly ◽  
Roy F Chemaly
Keyword(s):  
Enterococcus Faecium ◽  
Galleria Mellonella ◽  
Advisory Board ◽  
Vancomycin Resistant Enterococcus ◽  
Efficacy And Safety ◽  
Research Support ◽  
Colony Forming Units ◽  
Phage Cocktail ◽  
Vancomycin Resistant ◽  
Research Grant

Abstract Background Vancomycin-resistant Enterococcus faecium (VRE) is a major multidrug-resistant organism which may cause infection or colonization in hematopoietic cell transplant (HCT) patients. The use of VRE-specific bacteriophages (phages) may potentially help eradicate VRE colonization and subsequent infections. To test the efficacy and safety of phages against VRE in vivo, a cocktail combining four phages was used in a VRE-infected larva model. Methods The pre-screening model Greater Wax Galleria mellonella larva was used in this study. Larvae were infected with VRE by injecting a VRE strain isolated from stools of a VRE-colonized HCT patient at a concentration of 107 colony-forming units/10 μL. A single phage (MDA1) or a phage cocktail (MDA1, MDA2, MDA3, and MDA4) were also injected at a concentration of 106 colony-forming units/10 μL. Two model groups were tested; a prevention group (PG) and a treatment group (TG). For the PG, phages were administered 1 hour before bacterial injection whereas the TG were injected with phages 1 hour post bacterial injection. Control groups included larvae injected with bacteria alone, phages alone (to measure toxicity due to phage administration), sterile media (to measure any lethal effects due to physical trauma from the injection), or without any manipulation. Every group was composed of 5 larvae. The insect’s health state was observed and scored after 8 hours of incubation at 37ºC using a published health index scoring system. Results Phages improved survival of VRE-infected larvae (table). Only 32% of the VRE-infected larvae survived after 8 hours of infection whereas more than 80% survived when adding phages, whether phages were administered before or after VRE infection. The phage cocktail was shown to be more effective than the single phage MDA1 in improving survival (66% vs. 82% survival). Injecting larvae with phages alone was safe as the same survival rate was observed when compared with those injected with sterile media or those without manipulation. Conclusion The use of larva model G. mellonella allows for rapid and efficient screening of the bacterial virulence and phage efficacy and safety. Such results highlight the feasibility and the potential impact of phage therapy on VRE colonization and infections. Disclosures Roy F. Chemaly, MD, MPH, FACP, FIDSA, Chimerix: Advisory Board, Research Grant; Clinigen: Advisory Board; Merck: Advisory Board, Consultant, Grant/Research Support, Research Grant, Speaker’s Bureau; Oxford immunotec: Consultant, Grant/Research Support; Shire: Research Grant, Speaker’s Bureau; Viracor: Grant/Research Support.

scholarly journals Comparison of Carbapenem-Resistant Klebsiella pneumoniae Strains Causing Intestinal Colonization and Extraintestinal Infections: Clinical, Virulence, and Molecular Epidemiological Characteristics

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenli Liao ◽  
Na Huang ◽  
Ying Zhang ◽  
Yao Sun ◽  
Tao Chen ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Virulence Genes ◽  
Galleria Mellonella ◽  
Infection Model ◽  
Klebsiella Pneumonia ◽  
Intestinal Colonization ◽  
Infection Group ◽  
Carbapenem Resistant ◽  
Significant Difference ◽  
Epidemiological Characteristics

Carbapenem-resistant Klebsiella pneumonia (CRKP) infections has become a concerning threat. However, knowledge regarding the characteristics of intestinal CRKP isolates is limited. This study aimed to investigate and compare the clinical, virulence and molecular epidemiological characteristics of intestinal colonization and extraintestinal infections CRKP strains. The clinical characteristics were investigated retrospectively. Polymerase chain reaction was used to investigate the capsular serotype, virulence genes and carbapenemase genes. Capsular polysaccharide quantification assay, serum resistance assay, biofilm formation assay, and infection model of Galleria mellonella larvae were performed to compare the virulence and pathogenicity. Besides, multilocus-sequence-typing (MLST) and pulsed-field-gel-electrophoresis (PFGE) were conducted to explore the homology of intestinal CRKP isolates. A total of 54 intestinal CRKP isolates were included. The main capsular serotypes were K14, K64, and K19. C-reactive protein and the proportion of ICU isolation of the infection group were significantly higher than that of the colonization group (P < 0.05). The carrier rates of various virulence genes of CRKP in the infection group were mostly higher than those in the colonization group, wherein the carrier rates of peg-344 and rmpA were significantly different (P < 0.05). There was no significant difference in capsular polysaccharides, antiserum ability, biofilm formation ability between the two group (P > 0.05), but the lethality of the infection group to Galleria mellonella was significantly higher than that of the colonization group (P < 0.05). The MLST categorized the 54 isolates into 13 different sequence types. PFGE revealed that homology among the 54 CRKP strains was <80%. This study suggested that the CRKP strains in the infection group had higher virulence than those in the colonization group. The development of CRKP isolates colonizing in the intestine should be addressed in future clinical surveillance.

Evolution of hypervirulence in carbapenem-resistant Klebsiella pneumoniae in China: a multicentre, molecular epidemiological analysis

2019 ◽  
Vol 75 (2) ◽  
pp. 327-336 ◽  
Author(s):  
Yawei Zhang ◽  
Longyang Jin ◽  
Pengwen Ouyang ◽  
Qi Wang ◽  
Ruobing Wang ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Virulence Genes ◽  
Galleria Mellonella ◽  
Infection Model ◽  
Epidemiological Analysis ◽  
Virulence Plasmids ◽  
Carbapenem Resistant ◽  
Resistance Plasmid ◽  
Serum Killing ◽  
Evolution Of Resistance

Abstract Objectives Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) have been increasingly reported in China. Here, a multicentre, longitudinal surveillance study on CR-hvKP is described. Methods We retrospectively investigated carbapenem-resistant K. pneumoniae (CRKP) in 56 centres across China during 2015–17 and screened the virulence genes (iucA, iroN, rmpA and rmpA2) for the presence of virulence plasmids. Hypermucoviscosity, serum killing and Galleria mellonella lethality experiments were conducted to identify CR-hvKP among strains with all four virulence genes. Capsule typing, fitness and plasmid features of CR-hvKP were also investigated. Results A total of 1052 CRKP were collected. Among these, 34.2% (360/1052) carried virulence genes and 72 of them had all four of the virulence genes tested. Fifty-five (76.4%) were considered to be CR-hvKP using the G. mellonella infection model, with KPC-2-producing K64-ST11 being the most common type (80%, 44/55). Prevalence of CR-hvKP differed greatly between regions, with the highest in Henan (25.4%, 17/67) and Shandong (25.8%, 25/97). A significant increase in CR-hvKP among KPC-2-producing ST11 strains was observed, from 2.1% (3/141) in 2015 to 7.0% (23/329) in 2017 (P=0.045). Alarmingly, compared with classic CRKP, no difference in growth was found among CR-hvKP (P=0.7028), suggesting a potential risk for dissemination. The hybrid virulence and resistance-encoding plasmid evolved from pLVPK and the resistance plasmid harbouring blaKPC-2, indicating evolution existed between the hypervirulence and hyper-resistance plasmid. Conclusions CR-hvKP were more frequently detected than previously assumed, especially among KPC-2-producing ST11. Dissemination of hypervirulence could be extremely rapid due to limited fitness cost. Also, the evolution of resistance genes into hypervirulence plasmids was identified, presenting significant challenges for public health and infection control.

scholarly journals Comparison of Inhibitory and Bactericidal Activities and Postantibiotic Effects of LY333328 and Ampicillin Used Singly and in Combination against Vancomycin-Resistant Enterococcus faecium

1998 ◽  
Vol 42 (10) ◽  
pp. 2564-2568 ◽  
Author(s):  
Aldona L. Baltch ◽  
Raymond P. Smith ◽  
William J. Ritz ◽  
Lawrence H. Bopp
Keyword(s):  
New York ◽  
Enterococcus Faecium ◽  
Brain Heart Infusion ◽  
Bactericidal Effect ◽  
Considerable Effect ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Pharmacokinetic Studies ◽  
Mueller Hinton ◽  
Vancomycin Resistant

ABSTRACT One hundred ninety-five individual vancomycin-resistantEnterococcus faecium (VRE) isolates from five upstate New York hospitals were studied for antimicrobial susceptibilities to LY333328, quinupristin-dalfopristin, teicoplanin, ampicillin, and gentamicin. LY333328 was the most active antibiotic against VRE. The effect of media and methods on the antibacterial activity of LY333328, its synergy with ampicillin, and the postantibiotic effects (PAE) of LY333328 and ampicillin were evaluated. In microdilution tests, the MIC of LY333328 at which 90% of the isolates were inhibited (MIC90) was 2 μg/ml in Mueller-Hinton II (MH II) broth and 1 μg/ml in brain heart infusion (BHI) broth. In contrast, on MH II agar the MIC90was 4 μg/ml and on BHI agar it was >16 μg/ml. Bactericidal activity was observed for most strains at concentrations from 8 to ≥133 times the MIC of the tube macrodilution in MH II broth. A bactericidal effect of LY333328 plus ampicillin was demonstrated in time-kill studies, but there was great strain-to-strain variability. By the MH II agar dilution method, bacteristatic synergy (defined as a fractional inhibitory concentration of <0.5) with LY333328 and ampicillin was demonstrated for 61% of the strains tested. Under similar conditions, there was synergy with LY333328 and quinupristin-dalfopristin or gentamicin for 27 and 15% of the strains tested, respectively. The PAE of LY333328 was prolonged (23.0 h at 10 times the MIC). However, 50% normal pooled human serum decreased the PAE to 12.2 h at 10 times the MIC. Test conditions and media had a considerable effect on VRE susceptibilities to LY333328. The prolonged PAE of LY333328, a potent new bactericidal glycopeptide, and its synergy with ampicillin in a large proportion of strains suggest that further evaluation of this drug in pharmacokinetic studies and experimental infections, including those with VRE, is warranted.

scholarly journals Prevalence of the fosfomycin-resistance determinant, fosB3, in Enterococcus faecium clinical isolates from China

2014 ◽  
Vol 63 (11) ◽  
pp. 1484-1489 ◽  
Author(s):  
Chunhui Chen ◽  
Xiaogang Xu ◽  
Tingting Qu ◽  
Yunsong Yu ◽  
Chunmei Ying ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Susceptibility Testing ◽  
Clonal Complex ◽  
Clinical Isolates ◽  
Resistance Determinant ◽  
Circular Dna ◽  
Resistant Strains ◽  
The Common ◽  
Vancomycin Resistant ◽  
Fosfomycin Resistance

In order to investigate the prevalence of fosfomycin-resistance (fos) determinants in Enterococcus faecium, clinical strains were collected from hospitals throughout China between January 2008 and December 2009. Antimicrobial susceptibility testing was performed, after which the fos genes in all isolates and van genes in vancomycin-resistant isolates were characterized by PCR and sequencing. Conjugation experiments were carried out with fosB-positive E. faecium, DNA fragments flanking the fosB3 gene were sequenced and the genetic environment of fosB3 was analysed. Fosfomycin-resistant E. faecium (FREF) strains were characterized further by multilocus sequence typing (MLST) and PFGE. Among 145 E. faecium clinical isolates, 10 were resistant to fosfomycin with MICs >1024 mg l−1 including six vancomycin-resistant strains of which five were vanA-positive and the sixth vanM-positive. All ten FREF strains harboured the fosB3 gene. Fosfomycin resistance and fosB3 could be transferred by conjugation from nine isolates. The fosB3 and tnpA genes were located in a circular DNA intermediate in all FREF strains and reversely inserted into vanA transposon Tn1546 in four vanA-positive FREF isolates. Ten different PFGE types and seven MLST types were found among the ten fosB3-positive isolates, while all strains belonged to the common clonal complex CC17. In conclusion, the transferable fosfomycin-resistance determinant fosB3 plays an important role in E. faecium resistance to fosfomycin in China.

scholarly journals Virulence of Vancomycin-Resistant Enterococcus faecium According to Linezolid Resistance and Clinical Outbreak Status

2013 ◽  
Vol 57 (8) ◽  
pp. 3923-3927 ◽  
Author(s):  
Milena McLaughlin ◽  
Michael Malczynski ◽  
Chao Qi ◽  
Grace Barajas ◽  
Jordan Radetski ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Galleria Mellonella ◽  
Interaction Model ◽  
Content Type ◽  
Host Interaction ◽  
Linezolid Resistance ◽  
Related Pair ◽  
Significant Difference ◽  
Vancomycin Resistant ◽  
Poor Outcomes

ABSTRACTAssessing clinical virulence differences between vancomycin-resistantEnterococcus faecium(VREF) strains resistant to linezolid (LRVRE) and linezolid-susceptible VRE (LSVRE) strains is difficult due to confounding patient variables.Galleria mellonellais a validated host interaction model allowing straightforward organism virulence assessment. The objective of this study was to assess the virulence of VREF inG. mellonellaaccording to linezolid resistance and clinical outbreak status. A genetically related pair of VREF strains with and without genotypically confirmed linezolid resistance was selected for analysis. Additionally, six strains of LSVRE and two strains of LRVRE were selected according to epidemiologic outbreak status. Mortality ofG. mellonellawas assessed daily over a 5-day period and analyzed using Kaplan-Meier survival curves and log rank tests. Linezolid resistance did not have a significant effect onG. mellonellamortality in the genetically related pair (P= 0.93). There was no significant difference in mortality over time between strains (non-outbreak [i.e., no patient transmissions were recorded] [n= 2] versus outbreak [i.e., transmission occurred between 3 or more patients in a period of 30 days] [n= 6],P= 0.84; extensive transmission [i.e., the isolate was transmitted between at least 80 patients] [n= 2] versus limited transmission [i.e., the isolate was transmitted between fewer than 10 patients] [n= 4],P= 0.78). These results suggest that patients infected with LRVRE or outbreak strains of VREF are at no greater risk of poor outcomes mediated by organism virulence than those infected with LSVRE or non-outbreak strains.

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

2019 ◽  
Vol 87 (4) ◽  
pp. 195-203
Author(s):  
Anna Sieńko ◽  
Sławomir Czaban ◽  
Dominika Ojdana ◽  
Piotr Majewski ◽  
Anna Wieczorek ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Susceptibility Testing ◽  
Surface Protein ◽  
Hospital Environment ◽  
Vancomycin Resistant Enterococcus ◽  
Biofilm Production ◽  
Long Time ◽  
Vancomycin Resistant

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.

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