Frontiers in Public Health (Aug 2015)

Assessment of MALDI TOF MS as alternative tool for Streptococcus suis identification

  • Marta ePerez-Sancho,
  • Ana Isabel Vela,
  • Teresa eGarcía-Seco,
  • Marcelo eGottschalk,
  • Lucas eDominguez,
  • JOSE FRANCISCO FERNANDEZ-GARAYZABAL

DOI
https://doi.org/10.3389/fpubh.2015.00202
Journal volume & issue
Vol. 3

Abstract

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The accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identifying Streptococcus suis isolates obtained from pigs, wild animals and humans was evaluated using a PCR-based identification assay as the gold standard. In addition, MALDI-TOF MS was compared with the commercial multi-tests Rapid ID 32 STREP system. From the 129 S. suis isolates included in the study and identified by the molecular method, only 31 isolates (24.03%) had score values ≥2.300 and 79 isolates (61.24%) gave score values between 2.299-2.000. After updating the currently available S. suis MALDI Biotyper database with the spectra of three additional clinical isolates of serotypes 2, 7 and 9, most isolates had statistically significant higher score values (mean score: 2.65) than those obtained using the original database (mean score: 2.182). Considering the results of the present study, we suggest using a less restrictive threshold score of ≥2.000 for reliable species identification of S. suis. According to this cut-off value, a total of 125 S. suis isolates (96.9%) were correctly identified using the updated database. These data indicate an excellent performance of MALDI-TOF MS for the identification of S. suis.

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