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Plasmids and genes contributing to high-level quinolone resistance in Escherichia coli

Laura Vinué1, Mohamad R A Sater2, Ian C Herriott2

  • 1Massachusetts General Hospital, Boston, Massachusetts, USA.

International Journal of Antimicrobial Agents
|April 25, 2020
PubMed
Abstract

Insights

This study details plasmid sequencing from a highly quinolone-resistant E. coli strain. It identifies the genetic locations of four plasmid-mediated quinolone resistance (PMQR) genes and describes a novel cointegrate plasmid formed by insertion sequences.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Plasmid-mediated quinolone resistance (PMQR) is a significant concern in Enterobacterales.
  • Clinical strains with multiple PMQR genes are uncommon, necessitating further investigation into their genetic basis.

Purpose of the Study:

  • To determine the genetic locations of four distinct PMQR genes within a single clinical Escherichia coli strain.
  • To characterize the plasmids carrying these resistance genes after transfer to a susceptible host.

Main Methods:

  • Whole-genome sequencing of plasmid transconjugants using Illumina and Oxford Nanopore Technologies.
  • Plasmid profiling and size estimation via S1 nuclease pulsed-field gel electrophoresis (PFGE).
  • Analysis of plasmid structures, including cointegrate formation.

Main Results:

  • The parental strain harbored three plasmids, with transconjugant 8C receiving three distinct plasmids carrying the four PMQR genes (oqxAB, qepA1, qnrA1, and aac(6')1b-cr).
  • Transconjugant 7C acquired a novel IncN-IncF cointegrate plasmid (pMG333) formed by the ligation of two other plasmids (pMG334 and pMG335) via IS26 insertion sequences.
  • Complete nucleotide sequences of the plasmids were determined, revealing their genetic architecture and resistance gene content.

Conclusions:

  • This study provides the complete nucleotide sequences of plasmids harboring multiple PMQR genes in a single strain.
  • It elucidates the plasmid profiles resulting from genetic transfer and describes the formation of a cointegrate plasmid mediated by insertion sequences.
Keywords:
CiprofloxacinEscherichia coliIS26Plasmid-mediated quinolone resistance (PMQR) genesPlasmids

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