Assessment of MALDI-TOF MS as Alternative Tool for Streptococcus suis Identification.
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 and 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.
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense , Madrid , Spain ; Campus de Excelencia Internacional (CEI) Moncloa, Universidad Politécnica de Madrid (UPM), Universidad Complutense de Madrid (UCM) , Madrid , Spain.
Marta
M
Pérez-Sancho
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense , Madrid , Spain ; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense , Madrid , Spain.
Ana Isabel
AI
Vela
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense , Madrid , Spain.
Teresa
T
García-Seco
Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal , Saint-Hyacinthe, QC , Canada.
Marcelo
M
Gottschalk
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense , Madrid , Spain ; Campus de Excelencia Internacional (CEI) Moncloa, Universidad Politécnica de Madrid (UPM), Universidad Complutense de Madrid (UCM) , Madrid , Spain ; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense , Madrid , Spain.
Lucas
L
Domínguez
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense , Madrid , Spain ; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense , Madrid , Spain.
José Francisco
JF
Fernández-Garayzábal
MALDI-TOF MS; PCR; Streptococcus suis; biochemical tests; identification