Characterization of five escherichia coli isolates co-expressing ESBL and mcr-1 resistance mechanisms from different origins in China

Pei Zhang, Juan Wang, Xinglong Wang, Xue Bai, Jiangang Ma, Ruyi Dang, Yifei Xiong, Séamus Fanning, Li Bai*, Zengqi Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)
18 Downloads (Pure)


Present study characterized five Escherichia coli co-expressing ESBL and MCR-1 recovered from food, food-producing animals, and companion animals in China. Antimicrobial susceptibility tests, conjugation experiments, and plasmid typing were performed. Whole genome sequencing (WGS) was undertaken for all five isolates using either PacBio RS II or Illumina HiSeq 2500 platforms. The cefotaxime and colistin resistance encoded by blaCTX−M and mcr-1 genes, respectively, was transferable by conjugation either together or separately for all five strains. Interestingly, the ESBL and mcr-1 genes could be co-selected by cefotaxime, while the colistin only selected the mcr-1-carrying plasmids during the conjugation experiments. Five E. coli sequence types (ST88, ST93, ST602, ST162, and ST457) were detected. Although diverse plasmid profiles were identified, IncI2, IncFIB, and IncFII plasmid types were predominant. These five clonally unrelated isolates harbored the mcr-1 gene located on similar plasmid backbones, which showed high nucleotide similarity to plasmid pHNSHP45. The mcr-1 gene can be co-transmitted with blaCTX−M genes through IncI2 plasmids with or without ISApl1 in our study. Characterization of these co-existence ESBL and mcr-1 isolates extends our understanding on the dissemination of these resistance markers among bacteria of diverse origins.

Original languageEnglish
Article number1994
Number of pages9
JournalFrontiers in Microbiology
Publication statusPublished - 29 Aug 2019
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported in part by the National Science and Technology Infrastructure Program (2017YFC1601501), the National Natural Science Foundation of China (81402685 and 31702294), Fundamental Research Funds for the Central Universities (2452017295), Natural Science Basic Research Plan in Shaanxi Province (2018JQ3002), China Postdoctoral Science Foundation (2018T111114), China Agriculture Research System (CARS-39-14), and the Youth Innovation Team of Shaanxi Universities. The

Publisher Copyright:
© 2019 Zhang, Wang, Wang, Bai, Ma, Dang, Xiong, Fanning, Bai and Yang.


  • Co-occurrence
  • Conjugative plasmids
  • ESBL
  • Escherichia coli
  • Mcr-1 gene

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)


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