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目的 探讨CTX-M-15型大肠埃希菌的分子分布特征及质粒传播规律. 方法 232株CTX-M-15型大肠埃希菌鸟枪法测序序列从GenBank数据库获取,利用CGE在线工具获得菌株的MLST分型、耐药基因及质粒类型信息,应用eBURST软件绘制MLST分型结果聚类图. 结果 232株CTX-M-15型大肠埃希菌共检测出 37个MLST型别,其中以ST131菌株检出率较高,为35.34％(82/232).菌株中耐药基因数目为1～22个不等,出现耐药基因数目较多菌株的ST型别为ST131和ST617,其中blaOXA-1、aac(6') Ib-cr、aac(3)-Ⅱ、aadA、mph(A)等7种耐药基因在ST131菌株和非ST131菌株中的分布差异有统计学意义(P＜0.05或P＜0.01),且ST131菌株检出率高于非ST131菌株(P＜0.05或P＜0.01).菌株巾检测到blaOXA48、blaKPC2、HaNDM1、blaCMy、blaVIM等其他类型的β-内酰胺类耐药基因,主要的β内酰胺基因组合形式是blaTEM1+blaCTXM15,而在ST131中主要的组合形式是blaOXA1+blaCTX-M-14(32/82).检测到的不相容性质粒的类型有9种,其中IncF型质粒的检出率较高,为95.26％(221/232),该质粒在ST131菌株中的检出率为98.78％(81/82).菌株中IncF型复制子类型出现频率较高的是IncFIA+IncFIB+IncFII(83/232),在ST131菌株中上述复制子中检出率较高的是IncFIA+IncFII,为51.22％(42/82).IncF型质粒经pMLST分型可获得59种型别,F36:A4:B1、F31:A4:B1、F48:A1:B49型质粒主要存在于ST131菌株和CC10克隆复合体巾,而ST131菌株中主要的质粒类型是F2:A1:B-(38/82). 结论 CTX-M-15型耐药基因主要存在于ST131型别的大肠埃希菌株中,ST131菌株比其他菌株具有更强的适应能力,同种型别的质粒可以在亲缘关系相近的菌株之间传播.“,”Objective To study the distribution characteristics of and plasmid horizontal transfer in CTX-M-15-carrying Escherichia coli.Methods A total of 232 CTX-M-15-producing E.coli strains were obtained from GenBank,and CGE web server was used to collect information on MLST,types of plasmids,and drug resistance genes.The software eBURST was used to draw a dendrogram based on MLST results Results The CTX-M-55-producing E.coli strains were grouped into 37 distinct STs,with the predominant STs being ST131 (82/232),followed by ST678 (45/232).ST405 (17/232) and ST410 (17/232),ST167 (7/232),ST478 (6/232),and other STs (fewer than 6 strains).The number of drug resistance genes ranged from 1 to 22,with the strains ST131 and ST617 harboring the largest number of drug resistance genes.blaOXA-1,aac(6')Ib-cr,aac(3)-Ⅱ,aadA,and mph(A) were detected at a higher rate in the ST131 strain than in other strains.The rate at which those genes were detected in ST131 isolates and other STs differed significantly (P＜0.05 or P＜0.01).Moreover,other beta-lactam resistance genes such as blaOXA-18,blaKPC2,blaNDM,blaCMY and blaVIM were found in the isolates.The main beta lactam resistance gene found in the 232 strains was blaTEM-1 +blaCTX-M-15 (74/232),while genes found in the ST131 strains were mainly blaXA1+blaCTXM-M-15(32/82).Nine incompatible plasmids were detected in the 232 isolates.The IncF plasmid was detected at a rate of 95.26％ (221/232).Furthermore,this plasmid was detected at a rate of 98.78％ (81/82) in ST131 strains.IncF replicons found in the in 232 isolates were mainly IncFIA+ IncFIB + IncFII (83/232),while IncFIA + IncFII (42/82) predominated in ST131 isolates.The IncF plasmids were classified into 59 subtypes according to pMLST analysis,and the plasmid subtypes F36:A4:B1,F31:A4:B1,and F48:A1:B49 were mainly found in ST131 and clone complexes of CC10.However,the main plasmid subtype in the ST131 strain was F2:A1:B-.Conclusion The gene blaCTX-M-15 is mainly found in E.coli sequence type ST131.The ST131 strain has greater adaptability than other stains,and the same plasmid can be transferred among closely related isolates.