不同基质辅助激光解吸电离飞行时间质谱系统对链球菌鉴定性能的比较

Comparison of different matrix-assisted laser desorption ionization time of flight mass spectrometry systems for identification of streptococci

目的了解基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)对链球菌属临床菌株的鉴定能力。方法收集2015-2019年同济大学附属东方医院临床分离的链球菌,16SrRNA基因测序确定细菌种类。采用直接涂抹法平行使用Autof MS1000型质谱仪、VITEK MS质谱鉴定系统及Bruker Biotyper系统对菌株进行质谱鉴定。结果134株链球菌属细菌中,3套质谱鉴定系统对无乳链球菌、化脓链球菌、解没食子酸链球菌、戈登链球菌及变异链球菌的准确鉴定率均为100%。Bruker Biotyper和Autof MS1000型质谱仪对21株停乳链球菌及14株星座链球菌未能鉴定到亚种,5株缓症链球菌鉴定为口腔链球菌,肺炎链球菌和咽峡炎链球菌各有1株鉴定错误;Autof MS1000型质谱仪鉴定链球菌种水平置信度高于Bruker Biotyper系统。VITEK MS质谱鉴定系统可鉴定停乳链球菌的部分亚种,但14株星座链球菌未能鉴定到亚种,7株缓症链球菌鉴定为缓症链球菌/口腔链球菌,2株咽峡炎链球菌分别鉴定为星座链球菌和肺炎链球菌。结论3套质谱鉴定系统对链球菌属中临床常见的无乳链球菌、化脓链球菌可准确鉴定、直接报告,但是对一些种类菌株鉴定结果有误或不能鉴别亚种,需要DNA序列分析或结合血清学或其他补充实验来准确鉴定。

Objective To understand the ability of matrix-assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF MS)to identify clinical strains of Streptococcus spp..Methods The clinical isolates of Streptococcus spp.from Shanghai East Hospital Affiliated to Tongji University from 2015 to 2019 were collected,and the 16 SrRNA gene was sequenced to determine the identification results.The direct smear method was used in parallel to identify the strains using Autof MS1000,VITEK MS and Bruker Biotyper systems.Results Among the 134 strains of Streptococcus spp.,three sets of the MALDI-TOF-MS systems all correctly identified 100% of Streptococcus agalactiae,Streptococcus pyogenes,Streptococcus gallolyticus,Streptococcus gordon and Streptococcus mutans.Bruker Biotyper and Autof MS1000 systems failed to identify21 Streptococcus dysgalactiae strains and 14 Streptococcus constellatus strains to the subspecies level,and 5 Streptococcus mitis strains were identified as Streptococcus oralis,and there were 1 strain of Streptococcus pneumoniae and 1 strain of Streptococcus anginosus identified incorrectly.The level of confidence of the Autof MS1000 system in identifying Streptococcus spp.was higher than that of the Bruker Biotyper system.The VITEK MS system can identify some Streptococcus dysgalactiae ssp.,but it failed to identify 14 Streptococcus constellation strains to the subspecies level.Besides,7 Streptococcus mitis strains were identified as Streptococcus mitis/oralis,2 Streptococcus anginosus strains were identified as 1 Streptococcus constellatus and 1 Streptococcus pneumoniae respectively.Conclusion The three sets of MALID-TOF MS systems can accurately identify Streptococcus agalactiae and Streptococcus pyogenes,and their identification results can be reported directly.Gene sequencing,serological or other supplementary experiments are in need for confirming the idenfitication results of other Streptococcus spp.