中国畜牧兽医2025，Vol.52Issue(6)：2884-2892,9.DOI:10.16431/j.cnki.1671-7236.2025.06.040
猪源致病性大肠杆菌blaCTX-M-123基因的传播特性和适应性代价研究
Study on the Transmission Characteristics and Fitness Cost of blaCTX-M-123 Gene in Pathogenic Escherichia coli from Swine
摘要
Abstract
[Objective]The purpose of this experiment was to elucidate the location of blaCTX-M-123 gene in porcine Escherichia coli,and to explore the transmission capacity and fitness cost of the mobile genetic elements carried by blaCTX-M-123 gene.[Method]The intraspecific transfer ability of blaCTX-M-123 gene was evaluated by chemical transformation test,the location of blaCTX-M-123 gene was determined by whole genome sequencing,and the genetic environment of blaCTX-M-123 gene in Escherichia coli was analyzed.The minimum inhibitory concentration(MIC)of Escherichia coli 911 strain,Escherichia coli DH5α competent cells and inverters was determined by broth microdilution method.In addition,competition experiments were conducted to assess the fitness cost of the plasmid carrying blaCTX-M-123 gene,and the Galleria mellonella infection model was used for pathogenicity evaluation.[Result]One transformant,DH5α-pL1,was obtained through the transformation experiment,and its MIC value against ceftiofur was 256 mg/mL.The growth rate of DH5α-pL1 was higher than that of the recipient Escherichia coli DH5α competent cells,but lower than that of the wild-type strain 911.After 7 days of culture,the plasmid retention rate of DH5α-pL1 gradually declined,and after 24 h,the plasmid retention rate showed a certain fitness cost,with the relative competition index less than 1.The results of pathogenicity test showed that the survival rate of larval of Galleria mellonella was 100％in control and Escherichia coli DH5α competent cells groups.After 120 h injection of strains 911 and DH5α-pL1,the survival rate was 50％and 70％,respectively.[Conclusion]The plasmid carrying blaCTX-M-123 gene could be transferred intra-specifically and mediate drug resistance of the transformer,and the plasmid had weak stability and a certain fitness cost.In addition,the plasmid carrying blaCTX-M-123 gene had the effect of enhancing the virulence of the recipient bacteria,increasing the probability of infection and the difficulty of treatment.The results provided a theoretical basis for the study of drug resistance mechanism and prevention and control of bacteria.关键词
大肠杆菌/blaCTX-M-123基因/转化试验/适应性代价/致病性Key words
Escherichia coli/blaCTX-M-123 gene/transformation experiment/fitness cost/pathogenicity分类
农业科技引用本文复制引用
李琼,胡紫微,金钢铸,陈峥,刘伟成,韩生义,许春燕..猪源致病性大肠杆菌blaCTX-M-123基因的传播特性和适应性代价研究[J].中国畜牧兽医,2025,52(6):2884-2892,9.基金项目
河南省重点研发与推广专项(科技攻关)项目:饲料端禁抗后生猪致病性大肠杆菌病防控技术研发与应用(242102111032) （科技攻关）
青海省自然科学基金项目(青年):噬菌体鸡尾酒治疗多重耐药性大肠杆菌感染的效果评价与研究(2022-ZJ-953Q) （青年）
