Article open access publication

Typing of vancomycin-resistant enterococci with MALDI-TOF mass spectrometry in a nosocomial outbreak setting

Clinical Microbiology and Infection, Elsevier, ISSN 1198-743X

Volume 24, 10, 2018

DOI:10.1016/j.cmi.2018.03.020, Dimensions: pub.1101721023, PMID: 29581054,



  1. (1) Copenhagen University Hospital, grid.4973.9, Capital Region
  2. (2) Slagelse Hospital, grid.452905.f, Zealand Region
  3. (3) University of Copenhagen, grid.5254.6, KU
  4. (4) Hvidovre Hospital, grid.411905.8, Capital Region
  5. (5) State Serum Institute, grid.6203.7
  6. (6) Hvidovre
  7. (7) Rigshospitalet, grid.475435.4, Capital Region
  8. (8) Odense
  9. (9) Aarhus
  10. (10) Herning-Viborg
  11. (11) Esbjerg
  12. (12) Aalborg






OBJECTIVES: To investigate the usefulness of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) typing as a first-line epidemiological tool in a nosocomial outbreak of vancomycin-resistant Enterococcus faecium (VREfm). METHODS: Fifty-five VREfm isolates, previously characterized by whole-genome sequencing (WGS), were included and analysed by MALDI-TOF MS. To take peak reproducibility into account, ethanol/formic acid extraction and other steps of the protocol were conducted in triplicate. Twenty-seven spectra were generated per isolate, and spectra were visually inspected to determine discriminatory peaks. The presence or absence of these was recorded in a peak scheme. RESULTS: Nine discriminatory peaks were identified. A characteristic pattern of these could distinguish between the three major WGS groups: WGS I, WGS II and WGS III. Only one of 38 isolates belonging to WGS I, WGS II or WGS III was misclassified. However, ten of the 17 isolates not belonging to WGS I, II or III displayed peak patterns indistinguishable from those of the outbreak strain. CONCLUSIONS: Using visual inspection of spectra, MALDI-TOF MS typing proved to be useful in differentiating three VREfm outbreak clones from each other. However, as non-outbreak isolates could not be reliably differentiated from outbreak clones, the practical value of this typing method for VREfm outbreak management was limited in our setting.

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2018: Realized

Research area: Medicine

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2018: Level 1

Research area: Medicine

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Times Cited: 5

Field Citation Ratio (FCR): 4.27

Relative Citation ratio (RCR): 0.97

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