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

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.