浙江省人源猪链球菌鉴定及毒力基因检测分析

Identification and characterization of the virulence of Streptococcus suis from human patients in Zhejiang Province,China

目的鉴定浙江省2005-2020年散发猪链球菌感染者分离株血清型并检测其毒力基因,了解该地区临床致病株毒力基因的分布情况与分子流行病学特征。方法收集猪链球菌感染者临床分离株,采用传统细菌学方法及基质辅助激光解吸电离飞行时间质谱(MALDI TOF MS)鉴定的同时,利用聚合酶链(PCR)技术检测其链球菌属(tuf)、猪链球菌种(16S rRNA)、猪链球菌7型(Cps7H)、猪链球菌9型(Cps9D)与2型猪链球菌(Cps2J)/兼荚膜毒力基因以及毒力基因:溶菌酶释放蛋白(mrp)、胞外因子(epf)、溶血素(sly)、毒力相关序列(orf2)、纤连蛋白(fbps)、谷氨酸脱氢酶(gdh)、3-磷酸甘油醛脱氢酶(gapdh)等24种毒力基因携带情况。结果28株人源分离株经综合鉴定均为2型猪链球菌,毒力基因群检测结果显示,除salKR毒力基因以及1株ZJ-31菌株外,96.43%(27/28)的菌株均携带23种毒力基因;16S rRNA基因测序构建系统发育树,结果显示除来自2018年的ZJ-31菌株单独在另一分枝外,其它菌株同源性极高均在同一分枝。结论浙江省十几年来散发猪链球菌病的人源分离株大多为2型猪链球菌强毒力株,遗传进化显示近年来已出现个别不同来源分枝群菌株。

Streptococcus suis is an economically influential pathogen affecting pigs as well as a zoonotic cause of human disease.The purpose of this study was to examine Streptococcus suis isolates recovered from human infections in Zhejiang Province,China,from 2005-2020,in terms of their serotype distribution,virulence genes and genetic profiles.A total of 28 S.suis isolates recovered from clinical specimens were identified by conventional methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry.Isolates were also characterized through serotyping and co-agglutination,virulence-associated genes detected by PCR and genotypic profiles determined by 16S rRNA sequence typing.All human isolates were identified as Streptococcus suis type 2.A total of 96.43%(27/28)of isolates contained 17 virulence genes:Cps2J,mrp,orf2,fbps,gdh,gapdh,ciaHR,dltA,lgA1,manN,neuB,pgdA,purD,dpe IV,serum,sortase and sspA.Furthermore,16S rRNA sequence typing classified 27 of 28 isolates in the same clade.Strain ZJ-31,lacking the virulence genes epf,sly,endoB,Permease,rgg and sum,was in the other clade.Together,our results demonstrated that Streptococcus suis type 2 has predominated in Zhejiang Province in the past 10 years.Phylogenetic analysis indicated that a new S.suis clone is emerging and deserves attention.