scholarly journals Comparison of VITEK® 2, three different gradient strip tests and broth microdilution for detecting vanB-positive Enterococcus faecium isolates with low vancomycin MICs

2019 ◽  
Vol 74 (10) ◽  
pp. 2926-2929 ◽  
Author(s):  
Ingo Klare ◽  
Jennifer K Bender ◽  
Carola Fleige ◽  
Nancy Kriebel ◽  
Axel Hamprecht ◽  
...  
Keyword(s):  
Incubation Time ◽  
Enterococcus Faecium ◽  
Agar Medium ◽  
Standard Procedure ◽  
Vancomycin Resistance ◽  
Therapeutic Decision ◽  
Molecular Test ◽  
Broth Microdilution ◽  
Vancomycin Mics ◽  
Confirmatory Tests

Abstract Objectives In 2018, EUCAST issued a warning regarding unreliable results of gradient strip tests for confirming vancomycin resistance in enterococci. We compared the performance of various diagnostic standard and confirmatory tests to identify and determine vanB-type vancomycin resistance. Methods We analysed a collection of vanB-positive Enterococcus faecium isolates (n = 68) with low vancomycin MICs and compared the performance of VITEK® 2 (bioMérieux), broth microdilution and three gradient strip tests from different providers (Oxoid, Liofilchem and bioMérieux). For the latter we compared the standard procedure with a protocol with increased inoculum, a rich agar medium and a longer incubation time (‘macromethod’). Results The sensitivity of VITEK® 2 was 81% compared with 72% for broth microdilution and 61%–63% for the three gradient strip tests using standard conditions. The macromethod substantially improved the performance of all strip tests resulting in a sensitivity of 89%–96% after 48 h of incubation. Conclusions We recommend that EUCAST changes the present warning against the general use of MIC strips. When MIC strips are used to either exclude or confirm suspected vancomycin resistance in E. faecium, and a PCR is not available, the macromethod should be employed. For clinically relevant enterococci, where a rapid therapeutic decision is needed, a molecular test (e.g. PCR) should be favoured in order to save time and to further increase sensitivity.

scholarly journals Comparison of Vitek® 2, three different gradient strip tests and broth microdilution for detecting vanB-positive Enterococcus faecium isolates with low vancomycin MICs

2019 ◽  
Author(s):  
Ingo Klare ◽  
Jennifer K. Bender ◽  
Carola Fleige ◽  
Nancy Kriebel ◽  
Axel Hamprecht ◽  
...  
Keyword(s):  
Agar Medium ◽  
Standard Procedure ◽  
Vancomycin Resistance ◽  
Broth Microdilution ◽  
Minimal Inhibitory Concentrations ◽  
Specific Pcr ◽  
Vancomycin Mics ◽  
Confirmatory Tests ◽  
Improved Performance ◽  
Strip Test

AbstractObjectivesIn 2018, EUCAST issued a warning regarding unreliable results of gradient strip tests for confirming vancomycin resistance in enterococci. We compared the performance of various diagnostic standard and confirmatory tests to identify and determine vanB-type vancomycin resistance.MethodsWe analysed a collection of vanB-positive E. faecium isolates (n = 68) with low level vancomycin minimal inhibitory concentrations (MICs) and compared the performance of Vitek® 2 (bioMérieux), of broth microdilution and of three different gradient strip test providers (Oxoid, Liofilchem, bioMérieux). For the latter we compared the standard procedure vs. a protocol with increased inoculum, a rich agar medium and a longer incubation time (“macromethod”).ResultsThe sensitivity of Vitek® 2 was 81% of vanB-isolates compared to 72% for broth microdilution and 61 – 63% for the three gradient strip tests using standard conditions. The “macromethod” substantially improved performance of all strip tests resulting in a sensitivity of 89 – 96% at 48h readout.ConclusionsThe “macromethod” provided the overall best performance for recognition of vanB E. faecium. We therefore propose to adapt the EUCAST warning and to recommend the “macromethod” with an additional 48h readout or a confirmation by a vanB-specific PCR from culture.

scholarly journals Failure of Vitek2 to reliably detect vanB-mediated vancomycin resistance in Enterococcus faecium

2021 ◽  
Author(s):  
Sarah V Walker ◽  
Martina Wolke ◽  
Georg Plum ◽  
Robert E Weber ◽  
Guido Werner ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Vancomycin Resistance ◽  
Bacterial Suspension ◽  
Clinical Routine ◽  
Low Level ◽  
Vancomycin Mics ◽  
Reliable Detection ◽  
Before And After ◽  
B Test ◽  
Level Resistance

Abstract Objectives The increasing prevalence of VRE necessitates their reliable detection, especially for low-level resistance mediated by vanB in Enterococcus faecium. In this prospective study we analysed if vanB-mediated vancomycin resistance can be reliably detected by Vitek2. Methods One thousand, three hundred and forty-four enterococcal isolates from routine clinical specimens were tested by Vitek2 (bioMérieux, Nürtingen, Germany). Additionally, a bacterial suspension (with a turbidity equivalent to that of a 0.5 McFarland standard) was inoculated on chromID VRE screening agar (bioMérieux) and incubated for 48 h. If vancomycin tested susceptible by Vitek2 but growth was detected on the screening agar, PCR for vanA/vanB was performed (GeneXpert vanA/B test, Cepheid, Frankfurt, Germany). For isolates that tested susceptible to vancomycin by Vitek2 but were vanA/B positive, MICs were determined before and after cultivation in broth with increasing concentrations of vancomycin. Results One hundred and fifty-six out of 491 E. faecium were VRE and were predominantly vanB positive (81.0%). Of these, Vitek2 did not identify 14 as VRE (sensitivity 91.0%). By broth microdilution 9/14 isolates demonstrated high MICs (≥32 mg/L) and 5/14 showed low vancomycin MICs, which did not increase despite vancomycin exposure. Three of the 14 isolates demonstrated growth on chromID VRE; after vancomycin exposure seven additional isolates were able to grow on chromID VRE. Conclusions Vitek2 fails to detect vanB-mediated vancomycin resistance consistently, especially, but not limited to, low-level resistance. As this may lead to treatment failure and further dissemination of vanB VRE, additional methods (e.g. culture on VRE screening agar or PCR) are necessary to reliably identify vanB-positive enterococci in clinical routine.

scholarly journals Attributable mortality of vancomycin resistance in ampicillin-resistant Enterococcus faecium bacteremia in Denmark and the Netherlands: A matched cohort study

2021 ◽  
pp. 1-9
Author(s):  
Wouter C. Rottier ◽  
Mette Pinholt ◽  
Akke K. van der Bij ◽  
Magnus Arpi ◽  
Sybrandus N. Blank ◽  
...  
Keyword(s):  
Cohort Study ◽  
The Netherlands ◽  
Antibiotic Therapy ◽  
Enterococcus Faecium ◽  
Mortality Rates ◽  
Vancomycin Resistance ◽  
Attributable Mortality ◽  
Matched Cohort ◽  
Matched Cohort Study ◽  
The Impact

Abstract Objective: To study whether replacement of nosocomial ampicillin-resistant Enterococcus faecium (ARE) clones by vancomycin-resistant E. faecium (VRE), belonging to the same genetic lineages, increases mortality in patients with E. faecium bacteremia, and to evaluate whether any such increase is mediated by a delay in appropriate antibiotic therapy. Design: Retrospective, matched-cohort study. Setting: The study included 20 Dutch and Danish hospitals from 2009 to 2014. Patients: Within the study period, 63 patients with VRE bacteremia (36 Dutch and 27 Danish) were identified and subsequently matched to 234 patients with ARE bacteremia (130 Dutch and 104 Danish) for hospital, ward, length of hospital stay prior to bacteremia, and age. For all patients, 30-day mortality after bacteremia onset was assessed. Methods: The risk ratio (RR) reflecting the impact of vancomycin resistance on 30-day mortality was estimated using Cox regression with further analytic control for confounding factors. Results: The 30-day mortality rates were 27% and 38% for ARE in the Netherlands and Denmark, respectively, and the 30-day mortality rates were 33% and 48% for VRE in these respective countries. The adjusted RR for 30-day mortality for VRE was 1.54 (95% confidence interval, 1.06–2.25). Although appropriate antibiotic therapy was initiated later for VRE than for ARE bacteremia, further analysis did not reveal mediation of the increased mortality risk. Conclusions: Compared to ARE bacteremia, VRE bacteremia was associated with higher 30-day mortality. One explanation for this association would be increased virulence of VRE, although both phenotypes belong to the same well-characterized core genomic lineage. Alternatively, it may be the result of unmeasured confounding.

Evaluation of methods for detection of β-lactamase production in MSSA

2021 ◽  
Author(s):  
Robert Skov ◽  
David R Lonsway ◽  
Jesper Larsen ◽  
Anders Rhod Larsen ◽  
Jurgita Samulioniené ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Confirmatory Test ◽  
Disc Diffusion ◽  
Broth Microdilution ◽  
Confirmatory Tests ◽  
Correct Determination ◽  
Primary Test ◽  
Zone Edge ◽  
Evaluation Of Methods

Abstract Objectives Correct determination of penicillin susceptibility is pivotal for using penicillin in the treatment of Staphylococcus aureus infections. This study examines the performance of MIC determination, disc diffusion and a range of confirmatory tests for detection of penicillin susceptibility in S. aureus. Methods A total of 286 consecutive penicillin-susceptible S. aureus blood culture isolates as well as a challenge set of 62 MSSA isolates were investigated for the presence of the blaZ gene by PCR and subjected to penicillin-susceptibility testing using broth microdilution MIC determination, disc diffusion including reading of the zone edge, two nitrocefin tests and the cloverleaf test. Results Using PCR-based detection of blaZ as the gold standard, both broth microdilution MIC testing and disc diffusion testing resulted in a relatively low accuracy (82%–93%) with a sensitivity ranging from 49%–93%. Among the confirmatory tests, the cloverleaf test performed with 100% accuracy, while zone edge interpretation and nitrocefin-based tests increased the sensitivity of β-lactamase detection to 96%–98% and 82%–96% when using MIC determination or disc diffusion as primary test, respectively. Conclusions This investigation showed that reliable and accurate detection of β-lactamase production in S. aureus can be obtained by MIC determination or penicillin disc diffusion followed by interpretation of the zone edge as a confirmatory test for apparently penicillin-susceptible isolates. The more cumbersome cloverleaf test can also be used. Nitrocefin-based tests should not be used as the only test for confirmation of a presumptive β-lactamase-negative isolate.

scholarly journals Draft Genome Sequence of a Vancomycin-Resistant and Vancomycin-Dependent Enterococcus faecium Isolate

2016 ◽  
Vol 4 (2) ◽  
Author(s):  
Marion Blaschitz ◽  
Sarah Lepuschitz ◽  
Laura Wagner ◽  
Franz Allerberger ◽  
Alexander Indra ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Enterococcus Faecium ◽  
Prolonged Exposure ◽  
Draft Genome ◽  
Vancomycin Resistance ◽  
Draft Genome Sequence ◽  
Nosocomial Pathogens ◽  
Vancomycin Resistant Enterococci ◽  
Vancomycin Resistant ◽  
Faecium Isolate

Vancomycin-resistant enterococci have emerged as major nosocomial pathogens worldwide. While antimicrobial pressure promotes nosocomial colonization with these enterococci, prolonged exposure to vancomycin may foster the transition from vancomycin resistance to vancomycin dependence. Here, we report the draft genome sequence of a vancomycin-dependent Enterococcus faecium isolate showing partial teicoplanin dependence.

scholarly journals Homologous Recombination within Large Chromosomal Regions Facilitates Acquisition of β-Lactam and Vancomycin Resistance in Enterococcus faecium

2016 ◽  
Vol 60 (10) ◽  
pp. 5777-5786 ◽  
Author(s):  
Mónica García-Solache ◽  
Francois Lebreton ◽  
Robert E. McLaughlin ◽  
James D. Whiteaker ◽  
Michael S. Gilmore ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Genomic Dna ◽  
Large Scale ◽  
Vancomycin Resistance ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Single Nucleotide ◽  
Content Type ◽  
Donor Chromosome ◽  
Vancomycin Resistant

ABSTRACTThe transfer of DNA betweenEnterococcus faeciumstrains has been characterized both by the movement of well-defined genetic elements and by the large-scale transfer of genomic DNA fragments. In this work, we report on the whole-genome analysis of transconjugants resulting from mating events between the vancomycin-resistantE. faeciumC68 strain and the vancomycin-susceptible D344RRF strain to discern the mechanism by which the transferred regions enter the recipient chromosome. Vancomycin-resistant transconjugants from five independent matings were analyzed by whole-genome sequencing. In all cases but one, the penicillin binding protein 5 (pbp5) gene and the Tn5382vancomycin resistance transposon were transferred together and replaced the correspondingpbp5region of D344RRF. In one instance, Tn5382inserted independently downstream of the D344RRFpbp5gene. Single nucleotide variant (SNV) analysis suggested that entry of donor DNA into the recipient chromosome occurred by recombination across regions of homology between donor and recipient chromosomes, rather than through insertion sequence-mediated transposition. The transfer of genomic DNA was also associated with the transfer of C68 plasmid pLRM23 and another putative plasmid. Our data are consistent with the initiation of transfer by cointegration of a transferable plasmid with the donor chromosome, with subsequent circularization of the plasmid-chromosome cointegrant in the donor prior to transfer. Entry into the recipient chromosome most commonly occurred across regions of homology between donor and recipient chromosomes.

Mobilization of vancomycin resistance by transposon-mediated fusion of a VanA plasmid with an Enterococcus faecium sex pheromone-response plasmid

Gene ◽  
1996 ◽  
Vol 171 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Michael P. Heaton ◽  
Linda F. Discotto ◽  
Michael J. Pucci ◽  
Sandra Handwerger
Keyword(s):  
Sex Pheromone ◽  
Enterococcus Faecium ◽  
Vancomycin Resistance ◽  
Pheromone Response
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