{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T17:06:41Z","timestamp":1789664801288,"version":"4.0.1"},"reference-count":30,"publisher":"Cambridge University Press (CUP)","issue":"1","license":[{"start":{"date-parts":[[2024,11,11]],"date-time":"2024-11-11T00:00:00Z","timestamp":1731283200000},"content-version":"unspecified","delay-in-days":315,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["ASHE"],"published-print":{"date-parts":[[2024]]},"abstract":"<jats:title>Abstract<\/jats:title>\n\t  <jats:p><jats:italic>Enterococcus faecium<\/jats:italic> is a difficult-to-treat gram positive organism with increasing rates of resistance to vancomycin which is commonly mediated through the <jats:italic>vanA<\/jats:italic> gene cluster. There have been international reports of <jats:italic>E. faecium<\/jats:italic> isolates that are genotypically positive for <jats:italic>vanA<\/jats:italic> but phenotypically vancomycin-susceptible. These isolates, commonly called vancomycin-variable enterococci (VVE), can convert to phenotypic vancomycin resistance upon exposure to vancomycin. Multiple mechanisms for this genotypic-phenotypic mismatch have been reported and most commonly involve the regulatory components of the <jats:italic>vanA<\/jats:italic> gene cluster. VVE are challenging to identify unless microbiology labs routinely implement both genotypic and phenotypic screening methods. VVE has been associated with outbreaks and has become a prevalent pathogen in several countries. In this review, we summarize the mechanisms, microbiology and epidemiology of VVE. Clinicians must remain vigilant for VVE as diagnosis can be challenging and treatment failure on vancomycin is possible.<\/jats:p>","DOI":"10.1017\/ash.2024.449","type":"journal-article","created":{"date-parts":[[2024,11,11]],"date-time":"2024-11-11T11:28:07Z","timestamp":1731324487000},"source":"Crossref","is-referenced-by-count":12,"title":["\u201cKeeping us on our toes\u201d: a review of what clinicians need to know about vancomycin-variable <i>Enterococcus<\/i>"],"prefix":"10.1017","volume":"4","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8387-0823","authenticated-orcid":false,"given":"Marten R.","family":"Hawkins","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1037-3209","authenticated-orcid":false,"given":"Natalia","family":"Medvedeva","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3712-9188","authenticated-orcid":false,"given":"Hannah","family":"Wang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Niaz","family":"Banaei","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7585-1809","authenticated-orcid":false,"given":"Marisa K.","family":"Holubar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[2024,11,11]]},"reference":[{"key":"S2732494X24004492_ref14","article-title":"A novel resistance reversion mechanism in a vancomycin-variable Enterococcus faecium strain","author":"McInnes","year":"2023","journal-title":"bioRxiv"},{"key":"S2732494X24004492_ref19","first-page":"S15","article-title":"17: effect of vancomycin exposure on avancomycin variable Enterococcus faecium harbouring vanB","volume":"31","author":"Mowlaboccus","year":"2022","journal-title":"J Glob Antimicrob Resist"},{"key":"S2732494X24004492_ref13","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dky308"},{"key":"S2732494X24004492_ref9","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.03579-13"},{"key":"S2732494X24004492_ref26","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijmmb.2021.12.011"},{"key":"S2732494X24004492_ref2","doi-asserted-by":"publisher","DOI":"10.1016\/j.resmic.2023.104046"},{"key":"S2732494X24004492_ref16","doi-asserted-by":"publisher","DOI":"10.1101\/2022.07.29.501338"},{"key":"S2732494X24004492_ref10","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.04490-14"},{"key":"S2732494X24004492_ref11","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijantimicag.2023.106849"},{"key":"S2732494X24004492_ref12","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkaa541"},{"key":"S2732494X24004492_ref22","volume-title":"Performance Standards for Antimicrobial Susceptibility Testing","year":"2020"},{"key":"S2732494X24004492_ref17","doi-asserted-by":"publisher","DOI":"10.2807\/1560-7917.ES.2019.24.34.1900503"},{"key":"S2732494X24004492_ref27","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0193926"},{"key":"S2732494X24004492_ref24","doi-asserted-by":"publisher","DOI":"10.1186\/s12941-023-00552-8"},{"key":"S2732494X24004492_ref18","doi-asserted-by":"publisher","DOI":"10.1110\/ps.39101"},{"key":"S2732494X24004492_ref3","first-page":"382","article-title":"Detection of vancomycin-resistant Enterococcus faecium endocarditis after clearance of vancomycin-sensitive Enterococcus faecium bacteremia","volume":"28","author":"McEllistrem","year":"2022","journal-title":"Microb Drug Resist"},{"key":"S2732494X24004492_ref6","doi-asserted-by":"publisher","DOI":"10.3390\/microorganisms11010024"},{"key":"S2732494X24004492_ref15","doi-asserted-by":"publisher","DOI":"10.1016\/j.diagmicrobio.2014.06.012"},{"key":"S2732494X24004492_ref25","unstructured":"25. The European Committee on Antimicrobial Susceptibility Testing. EUCAST Expert Rules on Enterococcus spp. Version 3.2. 2023. https:\/\/www.eucast.org\/fileadmin\/src\/media\/PDFs\/EUCAST_files\/Expert_Rules\/2023\/ExpertRules_V3.2_20230113_Enterococcus.pdf. Accessed June 04, 2024."},{"key":"S2732494X24004492_ref20","doi-asserted-by":"publisher","DOI":"10.1016\/j.jmii.2015.08.003"},{"key":"S2732494X24004492_ref21","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.01125-14"},{"key":"S2732494X24004492_ref28","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.02180-19"},{"key":"S2732494X24004492_ref23","unstructured":"23. The European Committee on Antimicrobial Susceptibility Testing. EUCAST guidelines for detection of resistance mechanisms and specific resistances of clinical and\/or epidemiological importance. Version 2.0. 2017. https:\/\/www.eucast.org\/fileadmin\/src\/media\/PDFs\/EUCAST_files\/Resistance_mechanisms\/EUCAST_detection_of_resistance_mechanisms_170711.pdf. 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