{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T03:58:13Z","timestamp":1784865493484,"version":"3.55.0"},"reference-count":32,"publisher":"Microbiology Society","issue":"4","license":[{"start":{"date-parts":[[2025,4,4]],"date-time":"2025-04-04T00:00:00Z","timestamp":1743724800000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,4,4]]},"abstract":"<jats:p>\n                  <jats:bold>Introduction.<\/jats:bold>\n                  <jats:italic>Enterococcus faecium<\/jats:italic> clade B has recently been re-classified as <jats:italic>Enterococcus lactis<\/jats:italic>. Although <jats:italic>E. lactis<\/jats:italic> was previously associated with food products and probiotics, the recent re-classification has prompted the need for the accurate identification of this species and re-interpretation of its disease-causing ability. Since the re-classified <jats:italic>E. lactis<\/jats:italic> can currently only be identified by molecular techniques such as whole-genome sequencing, we constructed a MALDI Biotyper<jats:sup>\u00ae<\/jats:sup> custom database to rapidly identify and differentiate <jats:italic>E. lactis<\/jats:italic> causing bacteraemia from <jats:italic>E. faecium<\/jats:italic>.<\/jats:p>\n               <jats:p>\n                  <jats:bold>Hypothesis\/Gap statement.<\/jats:bold> The re-classification of <jats:italic>E. faecium<\/jats:italic> clade B as <jats:italic>E. lactis<\/jats:italic> warrants the development of rapid and accurate identification methods to distinguish these species, particularly in clinical settings where <jats:italic>E. lactis<\/jats:italic> may be misidentified as <jats:italic>E. faecium<\/jats:italic>.<\/jats:p>\n               <jats:p>\n                  <jats:bold>Aim.<\/jats:bold> The aim of this study was to construct a MALDI Biotyper<jats:sup>\u00ae<\/jats:sup> custom database to rapidly identify and differentiate <jats:italic>E. lactis<\/jats:italic> causing bacteraemia from <jats:italic>E. faecium<\/jats:italic>.<\/jats:p>\n               <jats:p>\n                  <jats:bold>Methodology.<\/jats:bold> A total of 97 enterococcal isolates, including 38 <jats:italic>E. lactis<\/jats:italic>, 51 <jats:italic>E. faecium<\/jats:italic> and 8 non-<jats:italic>E. faecium<\/jats:italic> non-<jats:italic>E. lactis<\/jats:italic> enterococci (<jats:italic>E. avium<\/jats:italic>, <jats:italic>E. casseliflavus<\/jats:italic>, <jats:italic>E. cecorum<\/jats:italic>, <jats:italic>E. durans<\/jats:italic>, <jats:italic>E. faecalis<\/jats:italic>, <jats:italic>E. faecium<\/jats:italic>, <jats:italic>E. gallinarum<\/jats:italic>, <jats:italic>E. lactis<\/jats:italic>, <jats:italic>E. mundtii<\/jats:italic> and <jats:italic>E. raffinosus<\/jats:italic>) were investigated. Whole-genome sequence analysis was used to confirm the species of each isolate. A MALDI Biotyper<jats:sup>\u00ae<\/jats:sup> in-house database was constructed using 29 <jats:italic>E. lactis<\/jats:italic> isolates and the ethanol\/formic acid\/acetonitrile preparation protocol. The in-house database was validated using the 97 enterococcal isolates and the extended direct transfer preparation protocol.<\/jats:p>\n               <jats:p>\n                  <jats:bold>Results.<\/jats:bold> Our in-house database correctly identified all isolates at the species level, including the <jats:italic>E. lactis<\/jats:italic> isolates, all of which were misidentified as <jats:italic>E. faecium<\/jats:italic> by the BioTyper<jats:sup>\u00ae<\/jats:sup> MBT Compass reference library (2022). Of the 38 <jats:italic>E. lactis<\/jats:italic> isolates, 84.2% (<jats:italic>n<\/jats:italic>=32) were identified at the high probable species level (score \u22652.300), while the remaining 15.8% (<jats:italic>n<\/jats:italic>=6) were identified at the probable species level (score 2.000\u20132.299). Similarly, all <jats:italic>E. faecium<\/jats:italic> isolates (<jats:italic>n<\/jats:italic>=51) were accurately identified, including 84.3% (<jats:italic>n<\/jats:italic>=43\/51) identified at the high probable species level and 15.7% (<jats:italic>n<\/jats:italic>=8\/51) identified at the probable species level.<\/jats:p>\n               <jats:p>\n                  <jats:bold>Conclusion.<\/jats:bold> Our study provides a ready-to-use custom MALDI spectral database that can be implemented in clinical diagnostic and research laboratories to accurately identify <jats:italic>E. lactis,<\/jats:italic> which is currently misidentified as <jats:italic>E. faecium<\/jats:italic> by the standard spectrum database available on commercial platforms.<\/jats:p>","DOI":"10.1099\/jmm.0.001995","type":"journal-article","created":{"date-parts":[[2025,4,4]],"date-time":"2025-04-04T15:20:19Z","timestamp":1743780019000},"source":"Crossref","is-referenced-by-count":2,"title":["Accurate identification of 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