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目的了解大肠埃希菌分离株eaeA基因的多态性。方法对不同来源的60株大肠埃希菌分离株的eaeA基因进行聚合酶链反应扩增后直接测序,测序结果在NCBI中进行BLASTn比对,根据比对相似性判定eaeA基因的型别。将获得型别的序列与GenBank中肠致病性大肠埃希菌(Enteropathogenic Escherichia coli,EPEC)和肠出血性大肠埃希菌(Enterohemorrhagic Escherichia coli,EHEC)代表性菌株型别的序列用Neighbor-joining法构建系统发生树,分析其进化关系。结果所有EHEC分离株的eaeA基因均为γ型,且序列完全一致。EPEC分离株的eaeA基因型以β1型为主,同时存在ε,κ,ι2,θ型。结论 EHEC分离株的eaeA基因相对保守,型别单一,而EPEC分离株的eaeA基因表现出较大的多态性。
Objective To understand the eaeA gene polymorphism of Escherichia coli isolates. Methods The eaeA gene of 60 Escherichia coli isolates from different sources was amplified by polymerase chain reaction (PCR) and sequenced directly. The results of sequencing were compared with each other by BLASTn in NCBI. The eaeA gene types were determined according to the similarities. The sequences of the obtained type and the representative strains of enteropathogenic Escherichia coli (EPEC) and Enterohemorrhagic Escherichia coli (EHEC) in GenBank were sequenced by Neighbor-joining Method to construct phylogenetic tree, analyze its evolutionary relationship. Results The eaeA genes of all EHEC isolates were all γ-type, and their sequences were identical. The eaeA genotypes of EPEC isolates mainly belonged to β1 type, with ε, κ, ι2 and θ types. Conclusion The eaeA gene of EHEC isolates is relatively conservative with a single haplotype. The eaeA gene of EPEC isolates shows a large polymorphism.