Optimization of the score cutoff value for routine identification of Staphylococcus species by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry

Huan Wen Han, Hsien Chang Chang, Ay Huei Hunag, Tsung Chain Chang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Staphylococcus species are important pathogens. We evaluated 2 score cutoffs (2.0 and 1.7) and the replicate number (a single or a duplicate test) on the identification of staphylococci using the Bruker matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). A collection of 440 clinical isolates (11 species) and 144 reference strains (36 species) was evaluated. For clinical isolates using a cutoff of 2.0 and duplicate tests, the rates of species, genus, and unreliable identifications were 93.4%, 5.7%, and 0.9% respectively, while the respective values were 99.3%, 0.2%, and 0.5% when the cutoff was 1.7. The species identification rates were significantly higher ( P< 0.01) when a cutoff of 1.7 or a duplicate test was used. Similar results were obtained for reference strains. In conclusion, a cutoff of 1.7 and duplicate tests are recommended for identification of staphylococci using MALDI-TOF MS.

Original languageEnglish
Pages (from-to)349-354
Number of pages6
JournalDiagnostic Microbiology and Infectious Disease
Volume83
Issue number4
DOIs
Publication statusPublished - 2015 Dec

All Science Journal Classification (ASJC) codes

  • Microbiology (medical)
  • Infectious Diseases

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