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Journal of Medical Microbiology logo Journal of Medical Microbiology

Volume 74, Issue 4

Accurate identification of causing bacteraemia by matrix-assisted laser desorption ionization-time of flight mass spectrometry Open Access

Abstract

clade B has recently been re-classified as . Although 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 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 causing bacteraemia from .

The re-classification of clade B as warrants the development of rapid and accurate identification methods to distinguish these species, particularly in clinical settings where may be misidentified as .

The aim of this study was to construct a MALDI Biotyper custom database to rapidly identify and differentiate causing bacteraemia from .

A total of 97 enterococcal isolates, including 38 , 51 and 8 non- non- enterococci (, , , , , , , , and ) 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 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.

Our in-house database correctly identified all isolates at the species level, including the isolates, all of which were misidentified as by the BioTyper MBT Compass reference library (2022). Of the 38 isolates, 84.2% (=32) were identified at the high probable species level (score ≥2.300), while the remaining 15.8% (=6) were identified at the probable species level (score 2.000–2.299). Similarly, all isolates (=51) were accurately identified, including 84.3% (=43/51) identified at the high probable species level and 15.7% (=8/51) identified at the probable species level.

Our study provides a ready-to-use custom MALDI spectral database that can be implemented in clinical diagnostic and research laboratories to accurately identify which is currently misidentified as by the standard spectrum database available on commercial platforms.

  • Received:
  • Accepted:
  • Published Online:
Keyword(s): bacteraemia , Enterococcus faecium , Enterococcus lactis and MALDI-TOF MS
© 2025 The Authors
  • This is an open-access article distributed under the terms of the Creative Commons Attribution License. This article was made open access via a Publish and Read agreement between the Microbiology Society and the corresponding author’s institution.
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2025-04-04
2025-04-27
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/content/journal/jmm/10.1099/jmm.0.001995
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Accurate identification of Enterococcus lactis causing bacteraemia by matrix-assisted laser desorption ionization-time of flight mass spectrometry
J. Med. Microbiol. 74, 001995 (2025); https://doi.org/10.1099/jmm.0.001995
/content/journal/jmm/10.1099/jmm.0.001995
/content/journal/jmm/10.1099/jmm.0.001995
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