贵州省死亡病例1型猪链球菌的分离及分子生物学特征分析

目的 对来自贵州省1例疑似人感染猪链球菌患者的血液标本进行细菌分离鉴定,了解该菌株的分子生物学特征,为病例的快速确诊提供病原学依据。方法 采用血培养法对疑似感染猪链球菌患者的血液进行细菌分离培养,对分离菌株采用细菌16S rRNA 基因通用引物进行PCR扩增和DNA序列测定,将测序结果通过GenBank数据库的BLAST程序进行在线比对,再用猪链球菌种特异的16S rRNA 基因进行猪链球菌种的鉴定,进一步分别采用PCR检测常见强致病性血清型1、2、7和9型特异的cps 1j、cps 2j、cps 7h和cps9h基因以鉴定其血清型,并对菌株毒力基因gapdh、mrp、sly和ef进行检测。结果 血培养分离出1株链球菌可疑菌株,序列比对结果显示该分离菌株16S rRNA基因与猪链球菌的同源性最高,进一步的猪链球菌特异性PCR检测显示分离菌株16S rRNA基因为阳性,血清型特异PCR检测结果显示cps 1j基因为阳性,而cps 2j、cps 7h和cps 9h基因为阴性,毒力基因检测结果显示分离菌株gapdh,sly和ef毒力基因为阳性,而mrp为阴性。结论 本次从疑似感染猪链球菌死亡病例分离的菌株为猪链球菌1型,其毒力特征为gapdh、sly和ef基因阳性,mrp基因阴性,该病例为1型猪链球菌感染所致,且菌株毒力较强。

Identification and characterization of Streptococcus suis serotype 1 strain isolated from a death case,Guizhou

Objective To isolate and characterize the bacterial strain isolated from a suspicious death case of human with Streptococcus suis infection in Guizhou province,and to provide etiological basis for the diagnosis of the case. Methods The blood sample from a suspicious patient with Streptococcus suis infection was used for bacteria isolation using blood culture bottle.The genus of suspected bacteria strain was primarily identified using universal 16S rRNA gene sequencing and was compared with sequences in the GeneBank.The species of the bacteria strain was identified using S.suis specific 16S rRNA gene.Serotype specific genes including cps 1j,cps 2j,cps 7h and cps 9h were tested using PCR to identify the serotype of the S.suis isolate.And the PCR was used to detect the virulence gene including mrp,sly and ef. Results One strain of S.suspicious bacteria was isolated from the blood sample and the DNA sequence comparison results showed that the 16S rRNA gene of the isolated strain was the highest homology with the genus of Streptococcus.The specific PCR detection of Streptococcus suis showed that the 16S rRNA gene of the isolated strain was positive.Serotype-specific PCR showed that the serotype 1 specific gene cps1j was positive,while the cps2j,cps7h and cps9h gene were negative.Virulence gene detection showed that the gapdh,sly and ef gene were positive,while mrp was negative. Conclusion The bacteria strain isolated from the suspicious case of human with S.suis infection was identified as Streptococcus suis serotype 1,carrying virulence gene gapdh,sly and ef,but did not carry gene mrp.The patient was caused by S.suis serotype 1 infection and the virulence of the strain was strong.