Contribution to Carbapenem Resistance and Fitness Cost of DcuS/DcuR, RcsC/RcsB, and YehU/YehT Two-Component Systems in CTX-M-15-Producing Escherichia coli

Microb Drug Resist. 2020 Apr;26(4):349-352. doi: 10.1089/mdr.2019.0027. Epub 2019 Oct 9.

Abstract

Alteration in two-component systems (TCSs), which are signal transduction pathways in prokaryotes, can result in antibiotic resistance. Recently, it has been shown that the overexpression, using a multicopy cloning vector, of the dcuR, rcsB, and yehT genes, which code for the response regulator (RR) part of TCSs, enhanced the minimal inhibitory concentrations (MICs) of carbapenems in Escherichia coli K-12 derivative KAM3. Herein, the contribution to carbapenem resistance of the DcuS/DcuR, RcsC/RcsB, and YehU/YehT TCSs was assessed in E. coli K-12 derivative BW25113 (A phylogroup) and 536 (B2 phylogroup) recipient strains in combination with extended-spectrum β-lactamase that exhibit a weak carbapenemase activity. The genes encoding both the sensor kinase (SK) and the RR, on the one hand, and the genes encoding the SK only, on the other hand, of these regulating pathways were disrupted. Subsequently, the mutants and their parental strains were transformed by a recombinant plasmid encoding the CTX-M-15 gene, before testing their susceptibility to carbapenems and their fitness. Results showed a trade-off between enhanced MICs for ertapenem, which remained above the clinical resistance breakpoint, and decreased growth rate, specifically for the 536 strain SK mutants. In conclusion, mutations in dcuS/dcuR, rcsC/rcsB, and yehU/yehT genes may be a pivotal first-step event in the development of carbapenem resistance.

Keywords: ESBL; Escherichia coli; TCS; carbapenem; fitness; resistance.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / metabolism
  • Carbapenems / pharmacology*
  • DNA-Binding Proteins / metabolism
  • Drug Resistance, Microbial / physiology
  • Ertapenem / pharmacology
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / microbiology
  • Escherichia coli K12 / drug effects*
  • Escherichia coli K12 / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Humans
  • Microbial Sensitivity Tests / methods
  • Multienzyme Complexes / metabolism
  • Phosphoprotein Phosphatases / metabolism
  • Protein Kinases / metabolism
  • Transcription Factors / metabolism
  • beta-Lactamases / metabolism

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Carbapenems
  • DNA-Binding Proteins
  • DcuR protein, E coli
  • Escherichia coli Proteins
  • Multienzyme Complexes
  • Transcription Factors
  • YehT protein, E coli
  • YehU protein, E coli
  • rcsC protein, E coli
  • RcsB protein, Bacteria
  • Protein Kinases
  • DcuS protein, E coli
  • Phosphoprotein Phosphatases
  • beta-lactamase CTX-M-15
  • beta-Lactamases
  • carbapenemase
  • Ertapenem