广西人感染猪链球菌病的病原学及分子生物学鉴定分析

Microbiologic and molecular biologic investigation of human Streptococcus suis infections in Guangxi

目的:用细菌分离培养和分子生物学方法鉴定猪链球菌,为确定疫情、及时治疗及控制提供依据。方法:疑似患者血液、脑脊液,死亡患者的肝、脾、肾等尸检组织进行分离培养、API 20 Strep生化鉴定、药敏试验及PCR检测。结果:从11份血液、4份脑脊液标本中分离出5株猪链球菌,API 20 Strep生化鉴定为猪链球菌Ⅱ型;经PCR检测5株菌均具有猪链球菌种特异性基因16SrRNA(spe)基因、猪链球菌2型特异性荚膜多糖编码基因(cps2J)和猪链球菌溶菌酶释放相关蛋白编码基因(mrp),1例死亡患者尸检组织标本和2例患者(1例为死亡病例)的脑脊液标本,具有猪链球菌2型特异性荚膜多糖编码基因(cps2J),脾脏组织和1份脑脊液标本具有猪链球菌溶菌酶释放相关蛋白编码基因(mrp),全部确定为猪链球菌2型,并携带强毒力基因。药敏试验表明,猪链球菌2型对万古霉素、氯霉素、头孢吡肟、头孢噻肟、头孢曲松、克林霉素敏感。结论:广西6起疫情均为人感染猪链球菌2型所致。

Objective： To detect S.suis by methods of microbiologic culture and molecular biology to provide laboratory evidence for outbreak containment and case treatment.Methods：Specimens of blood,CSF, or postmortem liver,spleen,and kidney tissues from human patients were collected for microbiologic culture.S.suis strains were identified by chemical reactions,antibiotic susceptibility and PCR.Results：Five strains of S.suis were isolated from 11 blood and 4 CSF specimens,all of which were diagnosed as type 2 by chemical reaction with API Strep 20.PCR on all isolates showed gene coding for species-specific 16S rRNA of S.suis,gene coding for the capsule of S.suis serotypes 2（cps2J） and the muramidase-released-protein（mrp） gene.Postmortem tissues from 1 death and CSF specimens from 2 patients（1 death） were all tested positive for cps2J,and spleen tissues and 1 CSF specimen positive for mrp,showing virulence factors in the specimens.Antibiotic susceptibility profile of the isolates inhibited sensitivity to vancomycin,chloramphenicol,cefepime,cefotaxime,cefotriaxone and clindamycin.Conclusion：All of the 6 human S.suis outbreaks in Guangxi are caused by S.suis serotype 2.