文献类型： 外文期刊

作者： Fang, Liang-Xing ² ; Li, Xing-Ping ¹ ; Li, Liang ¹ ; Chen, Mu-Ya ¹ ; Wu, Cai-Yan ³ ; Li, Lu-Lu ⁴ ; Liao, Xiao-Ping ¹ ; Li ¹ ;

作者机构： 1.South China Agr Univ, Natl Risk Assessment Lab Antimicrobial Resistance, Guangzhou, Guangdong, Peoples R China

2.South China Agr Univ, Guangdong Prov Key Lab Vet Pharmaceut Dev & Safet, Guangzhou, Guangdong, Peoples R China

3.Guangdong Acad Agr Sci, Inst Anim Hlth, Guangzhou, Guangdong, Peoples R China

4.Shandong Acad Agr Sci, Inst Anim Sci & Vet Med, Jinan, Shandong, Peoples R China

关键词： bla(CMY-2); chromosome-borne; ColE1-like plasmid; ISEcp1-mediated transposition; extended-spectrum cephalosporin

期刊名称：INFECTION AND DRUG RESISTANCE （ 影响因子：4.003； 五年影响因子：4.323 ）

ISSN： 1178-6973

年卷期： 2018 年 11 卷

页码：

收录情况： SCI

摘要： Background: CMY-2 is the most prevalent pAmpC beta-lactamase, but the chromosomal bla(CMY-2) gene transfer via horizontal transmission has been seldom reported. This study aimed to describe an ISEcp1-mediated transposition of a chromosomal bla(CMY-2) gene from Escherichia coli into a small endogenous ColE1-like plasmid, resulting in elevated resistance to extended-spectrum cephalosporins. Methods: Three ESCs-resistant ST641 E. coli strains EC6413, EC4103 and EC5106 harbored the bla(CMY-2) gene. S1-PFGE, I-ceu I-PFGE, Southern blotting and electroporation experiments were performed to investigate the location and transferability of bla(CMY-2). The genetic context and gene expression of bla(CMY-2) in the original isolates and the corresponding electroporants were explored by PCR mapping, primer walking strategy and RT-qPCR. Results: The bla(CMY-2) -containing region (ISEcp1-bla(CMY-2) Delta-blc-Delta yggR-Delta tnp1-orf7-orf8-orf9-Delta tnp2-Delta hsdR) was transposed into endogenous ColE1-like plasmid pSC137 in the process of electroporation at very low frequencies (10(-8)-10(-9)). The transpositions resulted in novel larger bla(CMY-2) -harboring ColE1-like plasmids with size of 14,845 bp, enabling increase in MICs of 2 to 8-fold for cefotaxime, ceftiofur, and ceftazidime in recipient strains over their respective original counterparts. Transcriptional level analysis revealed that the increased bla(CMY-2) expression was correlated with elevated MIC values of cephalosporins. The bla(CMY-2) transposition unit was identical to that in a clinical isolate E. coli TN44889 from France isolated in 2004. Conclusions: Our results firstly demonstrated that ISEcp1 mediated a transposition of chromosome-borne bla(CMY-2) into an endogenous ColE1-like plasmid by electroporation. Amplification of the bla(CMY-2) gene facilitates the strain adaptation to a changed environment with an elevated antibiotic pressure.