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 Failure of VITEK2 to reliably detect vanB- mediated vancomycin resistance in Enterococcus faecium

2020 ◽  
Author(s):  
Sarah V. Walker ◽  
Martina Wolke ◽  
Georg Plum ◽  
Robert E. Weber ◽  
Guido Werner ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Vancomycin Resistance ◽  
Bacterial Suspension ◽  
Initial Growth ◽  
Low Level ◽  
Test Kit ◽  
Before And After ◽  
Vancomycin Resistant ◽  
High Level ◽  
Level Resistance

AbstractObjectivesThe increasing prevalence of vancomycin resistant enterococci (VRE) necessitates a reliable detection of VRE especially for low level resistance mediated by vanB in Enterococcus faecium. In this prospective study we analyzed if vanB mediated vancomycin resistance can be reliably detected by Vitek2.Methods1344 enterococcal isolates from routine clinical specimens were tested by Vitek2 (bioMérieux, Nürtingen, Germany). Additionally, a bacterial suspension (0.5 McFarland) was inoculated on a chromID VRE screening agar (bioMérieux) and incubated for 48 hours. If vancomycin was tested susceptible by Vitek2 but growth was detected on the screening agar a PCR for vanA/vanB was performed (GeneXpert vanA/B test kit, Cepheid, Frankfurt, Germany). MICs of vancomycin susceptible by Vitek but vanA/B positive isolates were determined before and after cultivation in a broth with increasing concentration of vancomycin.Results156/492 of E. faecium were VRE, predominantly vanB (87.0%) of which 14 were not identified as VRE by Vitek2 (sensitivity 91.0%). The majority (9/14) demonstrated high-level MICs by broth dilution. Even after exposure to increasing vancomycin concentrations MICs remained nearly identical. Three of the undetected isolates demonstrated initial growth on chromID VRE, after the vancomycin exposure additional 7 isolates demonstrated growth on chromID VRE.ConclusionsVitek2 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 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 Identification of VanN-Type Vancomycin Resistance in an Enterococcus faecium Isolate from Chicken Meat in Japan

2012 ◽  
Vol 56 (12) ◽  
pp. 6389-6392 ◽  
Author(s):  
Takahiro Nomura ◽  
Koichi Tanimoto ◽  
Keigo Shibayama ◽  
Yoshichika Arakawa ◽  
Shuhei Fujimoto ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Gel Electrophoresis ◽  
Vancomycin Resistance ◽  
Pulsed Field Gel Electrophoresis ◽  
Chicken Meat ◽  
Large Plasmid ◽  
Content Type ◽  
Vancomycin Resistant ◽  
Faecium Isolate ◽  
Level Resistance

ABSTRACTFive VanN-type vancomycin-resistantEnterococcus faeciumstrains were isolated from a sample of domestic chicken meat in Japan. All isolates showed low-level resistance to vancomycin (MIC, 12 mg/liter) and had the same pulsed-field gel electrophoresis profile. The vancomycin resistance was encoded on a large plasmid (160 kbp) and was expressed constitutively. The VanN-type resistance operon was identical to the first resistance operon to be reported, with the exception of a 1-bp deletion invanTNand a 1-bp substitution invanSN.

scholarly journals Resistance to vancomycin and teicoplanin: an emerging clinical problem.

1990 ◽  
Vol 3 (3) ◽  
pp. 280-291 ◽  
Author(s):  
A P Johnson ◽  
A H Uttley ◽  
N Woodford ◽  
R C George
Keyword(s):  
Clinical Problem ◽  
Selective Advantage ◽  
Vancomycin Resistance ◽  
Cross Resistance ◽  
Resistant Bacteria ◽  
Coagulase Negative Staphylococci ◽  
Wide Range ◽  
Vancomycin Mics ◽  
High Level ◽  
Level Resistance

Vancomycin and teicoplanin are glycopeptides active against a wide range of gram-positive bacteria. For 30 years following the discovery of vancomycin in 1956, vancomycin resistance was not detected among normally susceptible bacteria recovered from human specimens. Since 1986, however, bacteria resistant to vancomycin or teicoplanin or both have been described. Strains of the genera Leuconostoc, Lactobacillus, Pediococcus, and Erysipelothrix seem inherently resistant to glycopeptides. Species and strains of enterococci and coagulase-negative staphylococci appear to have acquired or developed resistance. There are at least two categories of glycopeptide resistance among enterococci, characterized by either high-level resistance to vancomycin (MIC, greater than or equal to 64 mg/liter) and teicoplanin (MIC, greater than or equal to 8 mg/liter) or lower-level vancomycin resistance (MIC, 32 to 64 mg/liter) and teicoplanin susceptibility (MIC, less than or equal to 1 mg/liter). The two categories appear to have similar resistance mechanisms, although genetic and biochemical studies indicate that they have arisen independently. Among coagulase-negative staphylococci, strains for which vancomycin MICs are up to 20 mg/liter or teicoplanin MICs are 16 to 32 mg/liter have been reported, but cross-resistance between these glycopeptides varies. The selective advantage accorded to glycopeptide-resistant bacteria and the observation that high-level resistance in enterococci is transferable suggest that such resistance may be expected to increase in incidence. Clinicians and microbiologists need to be aware of this emerging problem.

Outbreak of Enterococcus faecium with Low-Level Resistance to Vancomycin in Japan

2012 ◽  
Vol 40 (5) ◽  
pp. e111
Author(s):  
Yukihiro Yamaguchi ◽  
Medical Doctor ◽  
Yukiko Moronaga ◽  
Chie Nagahara
Keyword(s):  
Enterococcus Faecium ◽  
Low Level ◽  
Level Resistance

scholarly journals Antimicrobial Susceptibility Patterns of Enterococci Causing Infections in Europe

1999 ◽  
Vol 43 (10) ◽  
pp. 2542-2546 ◽  
Author(s):  
M. A. Schouten ◽  
A. Voss ◽  
J. A. A. Hoogkamp-Korstanje
Keyword(s):  
Enterococcus Faecalis ◽  
Antimicrobial Susceptibility ◽  
Enterococcus Faecium ◽  
Vancomycin Resistance ◽  
European Countries ◽  
High Level ◽  
Susceptibility Patterns ◽  
Level Resistance

ABSTRACT In vitro susceptibilities of 4,208 enterococci (83%Enterococcus faecalis isolates, 13.6% Enterococcus faecium isolates, and 3.4% isolates of other species) from patients in 27 European countries towards 16 antibiotics were determined. High-level resistance to gentamicin varied by country (range, 1 to 49%; mean, 22.6% ± 12.3%) and per species (19.7%E. faecalis isolates, 13.6% E. faeciumisolates, 3.4% by other species). Vancomycin resistance was detected in 0.06% E. faecalis, 3.8% E. faecium, and 19.1% isolates of other species. All enterococci were susceptible to LY 333328 and everninomicin, and 25% of E. faecalisisolates and 85% of other enterococci were susceptible to quinupristin-dalfopristin. The MIC of moxifloxacin and trovafloxacin for ciprofloxacin-susceptible E. faecalis at which 90% of the isolates were inhibited was 0.25 to 0.5 μg/ml.

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