Analytical profiling of mutations in quinolone resistance determining region of gyrA gene among UPEC

PLoS One. 2018 Jan 4;13(1):e0190729. doi: 10.1371/journal.pone.0190729. eCollection 2018.

Abstract

Mutations in gyrA are the primary cause of quinolone resistance encountered in gram-negative clinical isolates. The prospect of this work was to analyze the role of gyrA mutations in eliciting high quinolone resistance in uropathogenic E.coli (UPEC) through molecular docking studies. Quinolone susceptibility testing of 18 E.coli strains isolated from UTI patients revealed unusually high resistance level to all the quinolones used; especially norfloxacin and ciprofloxacin. The QRDR of gyrA was amplified and sequenced. Mutations identified in gyrA of E.coli included Ser83Leu, Asp87Asn and Ala93Gly/Glu. Contrasting previous reports, we found Ser83Leu substitution in sensitive strains. Strains with S83L, D87N and A93E (A15 and A26) demonstrated norfloxacin MICs ≥1024mg/L which could be proof that Asp87Asn is necessary for resistance phenotype. Resistance to levofloxacin was comparatively lower in all the isolates. Docking of 4 quinolones (ciprofloxacin, ofloxacin, levofloxacin and norfloxacin) to normal and mutated E.coli gyrase A protein demonstrated lower binding energies for the latter, with significant displacement of norfloxacin in the mutated GyrA complex and least displacement in case of levofloxacin.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • DNA Gyrase / genetics*
  • DNA Gyrase / metabolism
  • Drug Resistance, Bacterial / genetics*
  • Escherichia coli Infections / microbiology
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Docking Simulation
  • Mutation
  • Quinolones / pharmacology*
  • Sequence Homology, Nucleic Acid
  • Urinary Tract Infections / microbiology
  • Uropathogenic Escherichia coli / drug effects
  • Uropathogenic Escherichia coli / genetics*
  • Uropathogenic Escherichia coli / metabolism

Substances

  • Anti-Bacterial Agents
  • Escherichia coli Proteins
  • Quinolones
  • DNA Gyrase

Grants and funding

The authors received no specific funding for this work.