猪链球菌1型临床分离株的鉴定和基因组学分析

Identification and genomics analysis of a clinical strain of Streptococcus suis serotype 1

从罹患肺炎型猪链球菌病的仔猪气管中分离出1株猪链球菌强毒株,命名为SS2011GZ,经PCR鉴定为血清1型。斑马鱼攻毒试验测得该菌株的半数致死量(LD50)为4.09×10^(4) CFU/mL,有较强毒力;全基因组测序分析显示,毒力基因型为mrp^(+)gdh^(+)epf^(+)sly^(+)fbps^(-)sao^(-),存在19个基因岛,24种耐药基因,共线性分析发现该菌株基因有大量重排、倒位、插入、缺失,基因发生树中处于独立的分支。结果表明本研究分离的猪链球菌1型为强毒力株,基因共线性较差,存在大量特殊基因和耐药基因,有重要的公共卫生学意义,需引起足够重视。

Streptococcus suis is an emerging zoonotic pathogenic bacterium.In this study,we isolated a strain from a piglet with pneumonia showing a high virulence,which was named SS2011 GZ.PCR assay demonstrated that the strain was S.suis and was confirmed as serotype 1.Pathogenicity experiment with zebra fish was performed which showed that the median lethal dose of the strain(LD50)was 4.09×10^(4) CFU/mL.Its virulence factors,antibiotic resistance genes and gene islands were analyzed via genome sequencing of the organism.And the results were that the virulence factors of this strain were mrp^(+)gdh^(+)epf^(+)sly^(+)fbps^(-)sao^(-).Altogether,19 gene islands and 24 antibiotic resistance genes were identified.The result of the collinearity analysis showed that a large number of genes were rearranged,inversely inserted and deleted.The gene phylogenetic tree displayed that SS2011 GZ was in a separate cluster,compared with the classical S.suis stains.SS2011 GZ possessed a poor gene collinearity,more special genes and multidrug resistance genes which called for serious attention and was therefore of great public health significance.