Mutations in blaKPC-3 That Confer Ceftazidime-Avibactam Resistance Encode Novel KPC-3 Variants That Function as Extended-Spectrum β-Lactamases

Antimicrob Agents Chemother. 2017 Apr 24;61(5):e02534-16. doi: 10.1128/AAC.02534-16. Print 2017 May.

Abstract

We identified four blaKPC-3 mutations in ceftazidime-avibactam-resistant clinical Klebsiella pneumoniae isolates, corresponding to D179Y, T243M, D179Y/T243M, and EL165-166 KPC-3 variants. Using site-directed mutagenesis and transforming vectors into Escherichia coli, we conclusively demonstrated that mutant blaKPC-3 encoded enzymes that functioned as extended-spectrum β-lactamases; mutations directly conferred higher MICs of ceftazidime-avibactam and decreased the MICs of carbapenems and other β-lactams. Impact was strongest for the D179Y mutant, highlighting the importance of the KPC Ω-loop.

Keywords: KPC; ceftazidime-avibactam; drug resistance mechanisms; site-directed mutagenesis.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Azabicyclo Compounds / pharmacology*
  • Bacterial Proteins / genetics*
  • Carbapenem-Resistant Enterobacteriaceae / drug effects
  • Carbapenem-Resistant Enterobacteriaceae / genetics
  • Carbapenems / pharmacology
  • Ceftazidime / pharmacology*
  • Drug Combinations
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Humans
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / genetics*
  • Microbial Sensitivity Tests
  • Mutagenesis, Site-Directed
  • beta-Lactamase Inhibitors / pharmacology*
  • beta-Lactamases / genetics*

Substances

  • Anti-Bacterial Agents
  • Azabicyclo Compounds
  • Bacterial Proteins
  • Carbapenems
  • Drug Combinations
  • avibactam, ceftazidime drug combination
  • beta-Lactamase Inhibitors
  • Ceftazidime
  • beta-Lactamases
  • beta-lactamase KPC-3, Klebsiella pneumoniae