基质辅助激光解析电离飞行时间质谱用于猪链球菌鉴定与聚类分析的研究

Identification and cluster analysis of Streptococcus suis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

目的 评估基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)技术对猪链球菌的鉴定与聚类分析的可行性。方法 将经生化鉴定为猪链球菌的18株临床分离株,分别采用涂抹甲酸法和甲酸-乙腈提取法对样品进行前处理,将MALDI-TOF-MS法的鉴定结果及蛋白质图谱进行分析对比,采集更优前处理方法的图谱自建数据库,18株猪链球菌进行聚类分析,同时对其进行PFGE同源性分析,对比两种分型结果。结果 两种前处理方法均能准确鉴定出猪链球菌,分值均在2.1以上,甲酸乙腈提取法的蛋白指纹图谱的基线更平滑,杂峰更少,可标识的离子峰更多;两种同源性分型的结果相比较显示,MALDI-TOF-MS的同源性结果与PFGE结果存在显著差异。结论 MALDI-TOF-MS对涂抹甲酸法和甲酸-乙腈提取法处理的菌株均可准确鉴定出猪链球菌,甲酸乙腈提取法可获得更优蛋白质图谱,MALDI-TOF-MS在同源性分析中发挥一定的分型作用,但还存在一定的局限性,还不能完全取代PFGE。

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.