Journal article
Accurate identification of Enterococcus lactis causing bacteraemia by matrix-assisted laser desorption ionization-time of flight mass spectrometry
Journal of medical microbiology, Vol.74(4), 001995
2025
PMID: 40184187
Appears in Open Access via Read & Publish Agreements
Abstract
Introduction
Enterococcus faecium clade B has recently been re-classified as Enterococcus lactis. Although E. lactis 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 E. lactis can currently only be identified by molecular techniques such as whole-genome sequencing, we constructed a MALDI Biotyper® custom database to rapidly identify and differentiate E. lactis causing bacteraemia from E. faecium.
Hypothesis/Gap statement
The re-classification of E. faecium clade B as E. lactis warrants the development of rapid and accurate identification methods to distinguish these species, particularly in clinical settings where E. lactis may be misidentified as E. faecium.
Aim
The aim of this study was to construct a MALDI Biotyper® custom database to rapidly identify and differentiate E. lactis causing bacteraemia from E. faecium.
Methodology
A total of 97 enterococcal isolates, including 38 E. lactis, 51 E. faecium and 8 non-E. faecium non-E. lactis enterococci (E. avium, E. casseliflavus, E. cecorum, E. durans, E. faecalis, E. faecium, E. gallinarum, E. lactis, E. mundtii and E. raffinosus) were investigated. Whole-genome sequence analysis was used to confirm the species of each isolate. A MALDI Biotyper® in-house database was constructed using 29 E. lactis 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.
Results
Our in-house database correctly identified all isolates at the species level, including the E. lactis isolates, all of which were misidentified as E. faecium by the BioTyper® MBT Compass reference library (2022). Of the 38 E. lactis isolates, 84.2% (n=32) were identified at the high probable species level (score ≥2.300), while the remaining 15.8% (n=6) were identified at the probable species level (score 2.000–2.299). Similarly, all E. faecium isolates (n=51) were accurately identified, including 84.3% (n=43/51) identified at the high probable species level and 15.7% (n=8/51) identified at the probable species level.
Conclusion
Our study provides a ready-to-use custom MALDI spectral database that can be implemented in clinical diagnostic and research laboratories to accurately identify E. lactis, which is currently misidentified as E. faecium by the standard spectrum database available on commercial platforms.
Details
- Title
- Accurate identification of Enterococcus lactis causing bacteraemia by matrix-assisted laser desorption ionization-time of flight mass spectrometry
- Authors/Creators
- Marhami Fahriani - School of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, Western Australia, AustraliaGeoffrey W Coombs - Australian Group on Antimicrobial ResistancePrincy Shoby - Murdoch UniversityHaley Hood - School of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, Western Australia, AustraliaDenise A Daley - Australian Group on Antimicrobial ResistanceChristopher A Mullally - School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, AustraliaShakeel Mowlaboccus - School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Publication Details
- Journal of medical microbiology, Vol.74(4), 001995
- Publisher
- Microbiology Society
- Number of pages
- 12
- Identifiers
- 991005758307007891
- Copyright
- © 2025 The Authors
- Murdoch Affiliation
- Centre for Biosecurity and One Health; School of Medical, Molecular and Forensic Sciences
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- Citation topics
- 1 Clinical & Life Sciences
- 1.23 Infection Management & Resistance
- 1.23.2108 Microbial Diagnostics
- Web Of Science research areas
- Microbiology
- ESI research areas
- Microbiology