中文摘要：

[目的]探讨gyrB基因区分鉴别肠道病原菌的能力,为临床快速鉴定病原菌提供依据。[方法]通过PCR扩增及测序方法,获得肠杆菌科和弧菌科的14种临床常见肠道病原菌gyrB基因序列,合并采集来自GenBank的标准菌株序列,采用距离法构建系统发育树。[结果]在系统发育树的拓扑结构中,除志贺氏菌、大肠杆菌、嗜水气单胞菌外,同一菌种的不同菌株均聚类形成具有较高的自举支持率单系类群。大肠杆菌演化支内混杂有志贺氏菌分支;嗜水气单胞菌的临床分离株与标准菌株相距较远,未能聚类成单系类群。另外,除乙型副伤寒沙门氏菌外,其余沙门氏菌gyrB序列在血清型水平呈现高度同源性,使得5种血清型各自聚类区分。[结论]采用gyrB基因作为肠道病原菌系统发育分析靶基因是合适的,其可以在菌种水平区分包含肠杆菌与弧菌科的肠道病原菌。

英文摘要：

[Objective] The discriminative power of gyrB gene sequence variations in the enteric pathogens was assessed by inspecting the topology of nucleotide acid phylogenetic tree. [Methods] GyrB gene sequences were amplified by PCR from a set of pathogens comprised of 100 clinical isolates belonging to 14 species within Enterobacteriaceae and Vibrionaceae.Gene tree was constructed with neighbor-joining method. [Results] Enhanced resolution was demonstrated for Salmonella choleraesuis subspecies choleraesuis,within which 5 of 6 serotypes were found to be homogeneous in their corresponding sequences.E. coli was overlapped with Shigella strains.A polyphyletic pattern was observed for Aeromonas hydrophila.Other organisms, including Yersinia enterocolitica,Enterobacter cloacae,Aeromonas veronii,Aeromonas caviae,Vibrio choleraesuis and Vibrio parahaemolyticus,formed monophyletic groups with consistently well resolved topologies. [Conclusion] The gyrB gene is an efficient target molecule for bacterial phylogenetic analysis because it yields high accuracy and resolution.