腹泻仔猪大肠埃希菌分离株ST4214的全基因组测序分析

Complete genome analysis of Escherichia coli ST4214 from piglets with diarrhea

目的 分析腹泻仔猪大肠埃希菌(E.coli)分离株血清型、毒力因子及耐药基因。方法 本课题组前期研究从腹泻仔猪粪便样本中分离到64株E.coli,本研究取其中含有毒力因子最多的1株进行全基因组测序分析。结果 E.coli分离株基因组序列为5.5 Mb,预测蛋白质编码序列数为5 743,与已知致病菌E.coli O145的基因重合率较低,为64.53%。经多位点序列分型分析,确定分离株为E.coli ST4214,血清型为O3∶H45。与病原菌O157∶H7、O145∶H28和O104∶H4的毒力基因比较表明:4株菌共同含有的毒力基因为354个,E.coli ST4214含有64种独特的毒力基因、编码鞭毛蛋白、Ⅳ型分泌蛋白、Ⅱ型分泌蛋白、溶血素、菌毛、肠毒素、荚膜多糖相关蛋白质。耐药基因E.coli分离株含有氨基香豆素抗性基因、磺胺类耐药基因、β-内酰胺抗性基因、多粘菌素耐药基因、肽抗生素抗性基因和抗生素耐药基因外排泵等多重耐药基因。结论 腹泻仔猪E.coli ST4214分离株是一株新菌株,具有较多毒力因子及耐药基因,可能与仔猪腹泻发病相关。

Objective To analyze the serotypes, virulence factors and drug resistance genes of Escherichia coli isolated from diarrhea piglets. Methods In our previous study, 64 strains of Escherichia coli were isolated from fecal samples of diarrhea piglets. In this study, the whole genome sequencing was used to examine the E.coli strain containing the most virulence factors. Results The genome sequence of E.coli isolates was 5.5 Mb, and the predicted protein coding sequence was 5743. The coincidence rate ofE.coli O145 was 64.53%. By MLST analysis, the E.coli isolates belonged to ST4214 and the serotype was O3∶H45. The comparison of virulence genes and drug resistance genes with pathogenic bacteria O157∶H7, O145∶H28 and O104∶H4 showed that the four strains shared 354 virulence genes, and E.coli ST4214 contained 64 unique virulence genes, encoding flagellin, type Ⅳ secretory protein, typeⅡsecretory protein, hemolysin, fimbria, enterotoxin, and capsular polysaccharide related protein. The results showed that theE.coli isolates contained multiple resistance genes, including aminocoumarin resistance gene, sulfonamides resistance gene, β-lactam resistance gene, polymyxin resistance gene, peptide antibiotic resistance gene and antibiotic resistance gene efflux pump. Conclusion E.coli ST4214 is a new strain with more virulence factors and drug resistance genes, which may be related to diarrhea of piglets.