浙江省人源猪链球菌鉴定及毒力基因检测分析

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。

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

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.