利用MLST技术对浙江省大肠杆菌O157的分子流行病学研究

Multilocus sequence typing analysis application in molecular epidemiological research of Escherichia coli O157 isolates in Zhejiang province

目的对浙江省2005-2010年大肠杆菌O157分离株进行分子分型研究,了解菌株间的遗传进化关系,为浙江省大肠杆菌O157监测及爆发疫情的控制提供基础。方法选择Pasteur大肠杆菌多位点序列分型(Multilocus SequenceTyping,MLST)方案,对大肠杆菌O157分离株及882364菌株进行MLST分型,确定菌株序列型(Sequence type,ST);采用DNAsp、eBURST、START2等软件进行分析。结果 30株菌中,27株O157∶H7菌株具备相同序列型(ST-284),占90%(27/30),其他3株菌序列型分别为ST-367、ST-125、ST-296。8个管家基因核苷酸多态性(Pi)范围为0.00119(polB)～0.00648(uidA),putP基因多态性位点比例最高(4.6%),trpA基因多态性位点比例最低(0.4%)。进化分析结果显示,这些序列型分别属于Group 1及Group 11群。结论浙江省动物源性大肠杆菌O157∶H7的主要序列型为ST-284,与江苏省病人株882364(ST-296)具有同一个进化祖先,提示应加强浙江省大肠杆菌O157病原学监测。

The objective was to investigate the molecular epidemiological feature of Escherichia coli O157 isolates in Zhejiang Province.A multilocus sequence typing（MLST） scheme was applied to identify sequences of 8 housekeeping genes including DNA polymerase（dinB）,isocitrate dehydrogenase（icdA）,p-aminobenzoate synthase（pabB）,polymerase PolII（polB）,proline permease,（putP）,tryptophan synthase subunit A（trpA）,tryptophan synthase subunit B（trpB） and beta-glucuronidase（uidA） from 29 EHEC O157 isolated between 2005 and 2010 in Zhejiang Province and 882364 isolated in Jiangshu Province.DNAsp,eBURST and START2 were applied to analyze the polymorphism of the eight housekeeping genes and the evolution of the EHEC O157.Four sequence types（STs）,named ST-284,ST-367,ST-125,and ST-296 were identified,which grouped into two lineages,Group 1 and Group 11.ST-284 had the most proportion of 90%（27/30）.The proportion of variable sites ranged from 0.4%（trpA） to 4.6%（putP）.The nucleotide diversity（Pi,average number of nucleotide differences per site between two randomly-selected isolates） ranged from 0.00119（polB）-0.00648（uidA）.Phylogenetic analysis suggested that these STs belong to two CCs（clone complex）.The data presented here provide new sights into molecular epidemiology feature of EHEC O157.MLST molecular typing of EHEC O157 isolates in Zhejiang Province call for intense surveillance efforts.It was an ideal tool to the investigation of the genetic evolution of.EHEC O157.