{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,26]],"date-time":"2026-01-26T20:31:44Z","timestamp":1769459504403,"version":"3.49.0"},"reference-count":16,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T00:00:00Z","timestamp":1768435200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Vancomycin-resistant Enterococci (VRE) are established nosocomial pathogens; however, vancomycin-dependent Enterococci (VDE) represent a rare and underrecognized phenomenon. These organisms paradoxically require vancomycin for growth due to mutations in cell wall precursor synthesis. Limited awareness and significant diagnostic challenges associated with VDE can lead to delayed recognition and treatment failure. We report a case of vancomycin-dependent Enterococcus faecium isolated from a liver transplant recipient receiving oral vancomycin prophylaxis for recurrent Clostridioides difficile infection. The isolate failed to grow on standard media but exhibited robust growth on vancomycin-supplemented agar, confirmed by vancomycin disc diffusion testing and PCR detection of the vanB gene. Additionally, we reviewed four further VDE cases identified over a two-year period in our tertiary care microbiology laboratory. All patients originated from complex care settings, had significant comorbidities, and had received prolonged glycopeptide therapy. We summarize the clinical features, diagnostic findings, and microbiological challenges encountered across this case series. This series documents the first reported Canadian case of VDE and highlights the critical need for clinical vigilance and diagnostic suspicion in high-risk patients with prior enterococcal colonization and ongoing glycopeptide exposure. Laboratory findings such as failure to grow on blood agar coupled with growth around vancomycin discs should prompt specific evaluation for VDE. Our findings reinforce the necessity for targeted antimicrobial stewardship and infection prevention strategies and underscore the remarkable evolutionary adaptability of Enterococci under sustained antimicrobial pressure.<\/jats:p>","DOI":"10.3390\/microorganisms14010193","type":"journal-article","created":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T11:13:21Z","timestamp":1768475601000},"page":"193","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["\u201cHiding in Plain Sight\u201d: A Retrospective Clinical and Microbiological Review of Vancomycin-Dependent Enterococci at a Tertiary Care Centre\u2014A Case Report"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1279-1738","authenticated-orcid":false,"given":"Ruchika","family":"Bagga","sequence":"first","affiliation":[{"name":"Department of Pathobiology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada"},{"name":"Victoria Hospital, London Health Sciences Centre, London, ON N6A 5W9, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Johan","family":"Delport","sequence":"additional","affiliation":[{"name":"Department of Pathobiology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada"},{"name":"Victoria Hospital, London Health Sciences Centre, London, ON N6A 5W9, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alice","family":"Kanyua","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine and Pathology, Aga Khan University, Nairobi 00100, Kenya"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-7139-8134","authenticated-orcid":false,"given":"Kumudhavalli","family":"Kavanoor Sridhar","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, ON M5S 3K3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1086\/321815","article-title":"Vancomycin-Resistant Enterococci: Mechanisms and Clinical Observations","volume":"33","author":"Eliopoulos","year":"2001","journal-title":"Clin. Infect. Dis."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1017\/S0950268800030478","article-title":"High-level vancomycin-resistant enterococci causing hospital infections","volume":"103","author":"Uttley","year":"1989","journal-title":"Epidemiol. Infect."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1038\/nrmicro2761","article-title":"The rise of the Enterococcus: Beyond vancomycin resistance","volume":"10","author":"Arias","year":"2012","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1221","DOI":"10.1586\/14787210.2014.956092","article-title":"Mechanisms of antibiotic resistance in enterococci","volume":"12","author":"Miller","year":"2014","journal-title":"Expert Rev. Anti Infect. Ther."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1128\/AAC.43.1.41","article-title":"Vancomycin-dependent Enterococcus faecalis clinical isolates and revertant mutants","volume":"43","author":"Chauvel","year":"1999","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1277","DOI":"10.3201\/eid1007.030993","article-title":"Nosocomial infection with vancomycin-dependent enterococci","volume":"10","author":"Tambyah","year":"2004","journal-title":"Emerg. Infect. Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"926","DOI":"10.1016\/j.jmii.2016.08.007","article-title":"Vancomycin-dependent Enterococcus faecium can easily be obscured","volume":"50","author":"Kuo","year":"2017","journal-title":"J. Microbiol. Immunol. Infect."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"318","DOI":"10.1016\/j.pathol.2018.11.012","article-title":"Vancomycin dependent Enterococcus: An unusual mutant?","volume":"51","author":"Sukumaran","year":"2019","journal-title":"Pathology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"734","DOI":"10.1093\/jac\/40.5.734","article-title":"Vancomycin-dependent enterococci: Curious phenomenon or serious threat?","volume":"40","author":"Stewart","year":"1997","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"22","DOI":"10.7326\/0003-4819-121-1-199407010-00004","article-title":"Urinary tract infection with an Enterococcus faecalis isolate that requires vancomycin for growth","volume":"121","author":"Fraimow","year":"1994","journal-title":"Ann. Intern. Med."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"299","DOI":"10.3343\/kjlm.2009.29.4.299","article-title":"Microbiological and Epidemiological Characteristics of Vancomycin-dependent Enterococci","volume":"29","author":"Hwang","year":"2009","journal-title":"Ann. Lab. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"686","DOI":"10.1128\/CMR.13.4.686","article-title":"Vancomycin-resistant enterococci","volume":"13","author":"Cetinkaya","year":"2000","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2770","DOI":"10.1128\/jcm.33.10.2770-2773.1995","article-title":"Vancomycin-dependent Enterococcus faecium isolated from stool following oral vancomycin therapy","volume":"33","author":"Dever","year":"1995","journal-title":"J. Clin. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"783","DOI":"10.1097\/00005373-200004000-00035","article-title":"Vancomycin-dependent enterococcal strains: Case report and review","volume":"48","author":"Yowler","year":"2000","journal-title":"J. Trauma"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1268","DOI":"10.1086\/313456","article-title":"An outbreak of vancomycin-dependent Enterococcus faecium in a bone marrow transplant unit","volume":"29","author":"Kirkpatrick","year":"1999","journal-title":"Clin. Infect. Dis."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"765","DOI":"10.1093\/ndt\/14.3.765","article-title":"Vancomycin-dependent enterococci in a uraemic patient with sclerosing peritonitis","volume":"14","author":"Majumdar","year":"1999","journal-title":"Nephrol. Dial. Transplant."}],"container-title":["Microorganisms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2607\/14\/1\/193\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,26]],"date-time":"2026-01-26T10:40:34Z","timestamp":1769424034000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2607\/14\/1\/193"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,15]]},"references-count":16,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["microorganisms14010193"],"URL":"https:\/\/doi.org\/10.3390\/microorganisms14010193","relation":{},"ISSN":["2076-2607"],"issn-type":[{"value":"2076-2607","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,15]]}}}