猪链球菌的分离鉴定及16S rDNA序列分析

Isolation,identification and 16S rDNA sequencehomology of Streptococcus suis

为明确导致新疆某猪场猪急性死亡的病原菌,试验对采集的猪病变淋巴结、肺脏进行病原菌分离培养、形态观察、16S rDNA测定、生化鉴定、药敏试验以及PCR血清型鉴定。将该分离株与国内外13株分离株构建系统进化树进行比对分析。结果显示:分离菌株镜检观察为革兰氏阳性长链状球菌,具有β溶血性,可发酵大多数糖类,符合猪链球菌的生化特性;分离菌株16S rDNA序列与猪链球菌标准菌株ATCC 43765 (GenBank登录号:NR_115737.1)同源性为100%;采用PCR方法对分离菌株进行血清型鉴定扩增出约390 bp的荚膜血清9型特异性条带。分离菌株对林可霉素、多西环素、青霉素钠、环丙沙星、头孢噻呋、氟苯尼考、替米考星、氧氟沙星、磺胺嘧啶钠、硫酸黏菌素、氨苄西林钠11种药物敏感,对四环素、庆大霉素、阿莫西林表现耐药。研究表明,分离株为猪链球菌,荚膜血清9型,命名为XJS9。

In order to clarify the pathogenic bacteria that caused the acute death of pigs in a pig farm in Xinjiang,the test carried out the isolation and culture of pathogenic bacteria,morphological observation,16S rDNA determination,biochemical identification,drug sensitivity test and PCR serotype identification on the collected diseased lymph nodes and lung tissues of pigs.A phylogenetic tree was constructed from this isolated strain and 13 domestic and foreign isolates for comparative analysis.The results showed that the isolated strain was gram-positive long-streptococcus observed under microscopy.It hadβ-hemolytic properties which can ferment most sugars,and conforms to the biochemical characteristics of Streptococcus suis.The 16S rDNA sequence of the isolated strain was comparable to the standard strain ATCC of Streptococcus suis.43765(GenBank accession number:NR_115737.1)had a homology of 100%.The serotype identification of the isolated strains by PCR method was used to amplify a type 9-specific band with a size of about 390 bp.The isolated strains were p-lincomycin,doxycycline,penicillin sodium,ciprofloxacin,ceftiofur,florfenicol,tilmicosin,ofloxacin,sulfadiazine sodium,colistin sulfate,ampicillin Cillin sodium was sensitive to 11 drugs and was resistant to tetracycline,gentamicin,and amoxicillin.The study indicated that the isolated strain was Streptococcus suis,capsular serotype 9,named XJS9.