Identification and cluster analysis of Streptococcus suis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry / 公共卫生与预防医学

ABSTRACT

Objective To evaluate the feasibility of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for identification and cluster analysis of Streptococcus suis. Methods Eighteen clinical isolates biochemically identified as Streptococcus suis were pre-treated by smearing formic acid method and formic acid-acetonitrile extraction method. The identification results and protein profiles of MALDI-TOF-MS method were analyzed and compared. A self-constructed database of profiling with better pretreatment method was established, and cluster analysis was performed on the 18 strains of Streptococcus suis. At the same time, PFGE homology analysis was performed to compare the results of the two genotyping. Results Both pretreatment methods could accurately identify Streptococcus suis with scores above 2.1. The protein fingerprint of formic acid and acetonitrile extraction method had a smoother baseline, fewer miscellaneous peaks and more identifiable ion peaks. Comparison of the results of homology typing showed that the homology results of MALDI-TOF-MS were significantly different from those of PFGE. Conclusion MALDI-TOF-MS can accurately identify Streptococcus suis for the strains pre-treated with formic acid method or formic acid-acetonitrile extraction method, and the formic acid-acetonitrile extraction method can obtain a better protein mapping. MALDI-TOF-MS can play a certain role in typing, but it still has some limitations and cannot completely replace the PFGE.