携带bla_(CTX-M-65)、rmtB和fosA3多重耐药质粒pHN7A8的适应性研究

Fitness Cost of a Multidrug Plasmid Carrying bla_(CTX-M-65),rmtB,and fosA3

为分析携带blaCTX-M-65、rmtB和fosA3多重耐药质粒pHN7A8的适应性代价,将犬源大肠杆菌7A8的多重耐药质粒pHN7A8转化入大肠杆菌JM109中,获得转化子7A8JT,并采用生长曲线测定和竞争试验方法研究pHN7A8对宿主菌适应性的影响。结果表明,携带pHN7A8的转化子7A8JT和受体菌JM109的生长曲线相似,但前者对于后者有竞争优势,未发现质粒pHN7A8对宿主菌产生适应性代价。携带blaCTX-M-65、rmtB和fosA3的多重耐药质粒pHN7A8能在宿主菌中稳定传代,临床上应警惕大量使用或滥用抗菌药物对其形成的选择压力,以防止多重耐药质粒进一步扩散。

The objective of this study was to examine the fitness cost of a multidrug plasmid pHN7A8 carrying blaCTX-M-65,rmtB,and fosA3.Plasmid pHN7A8 carrying blaCTX-M-65,rmtB,and fosA3 from E.coli 7A8 was transferred into E.coli JM109 by electroporation.Transformant7A8 JT containing pHN7A8 was obtained.Growth curve and growth competition experiments were performed to assess the fitness cost of pHN7A8 upon its host.Growth curve showed no significant difference between the transformant carrying pHN7A8 and sensitive recipient E.coli JM109.Competition experiments between E.coli JM109 strain and transformant 7A8 JT revealed a competitive advantage for the transformant versus the recipient.The results showed that no fitness cost was observed for plasmid pHN7A8.More attention should be taken into account the effect of the clinical use of antibiotics on the selection of multidrug resistance encoding plasmids.