Loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing K1-ST23 hypervirulent Klebsiella pneumoniae

Virulence. 2024 Dec;15(1):2348251. doi: 10.1080/21505594.2024.2348251. Epub 2024 May 2.

Abstract

Objectives: This study aimed at revealing the underlying mechanisms of the loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing hypervirulent Klebsiella pneumoniae (hvKp).

Methods: Here we longitudinally recovered 3 non-carbapenemase-producing K1-ST23 hvKp strains at a one-month interval (KP29105, KP29499 and KP30086) from an elderly male. Antimicrobial susceptibility testing, whole genome sequencing, transcriptomic sequencing, gene cloning, plasmid conjugation, quantitative real-time PCR (qRT-PCR), and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) were conducted.

Results: Among the 3 hvKp strains, KP29105 was resistant to the third- and fourth-generation cephalosporins, KP29499 acquired resistance to both ceftazidime-avibactam and carbapenems, while KP30086 restored its susceptibility to ceftazidime-avibactam, imipenem and meropenem but retained low-level resistance to ertapenem. KP29105 and KP29499 carried plasmid-encoded genes blaCTX-M-15 and blaCTX-M-71, respectively, but KP30086 lost both. Cloning of gene blaCTX-M-71 and conjugation experiment of blaCTX-M-71-carrying plasmid showed that the transformant and transconjugant were susceptible to ceftazidime-avibactam but had a more than 8-fold increase in MICs. Supplementation with an outer membrane permeabilizer could reduce the MIC of ceftazidime-avibactam by 32 folds, indicating that porins play a key role in ceftazidime-avibactam resistance. The OmpK35 of the 3 isolates was not expressed, and the OmpK36 of KP29499 and KP30086 had a novel amino acid substitution (L359R). SDS-PAGE and qRT-PCR showed that the expression of porin OmpK36 of KP29499 and KP30086 was significantly down-regulated compared with KP29105.

Conclusions: In summary, we reported the rare ceftazidime-avibactam resistance in a non-carbapenemase-producing hvKp strain. Resistance plasmid carrying blaCTX-M-71 and mutated OmpK36 had a synergetic effect on the resistance.

Keywords: CTX-M-71; Hypervirulent Klebsiella pneumoniae; OmpK36; ceftazidime-avibactam resistance; non-carbapenemase-producing strain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Anti-Bacterial Agents* / pharmacology
  • Azabicyclo Compounds* / pharmacology
  • Bacterial Proteins* / genetics
  • Bacterial Proteins* / metabolism
  • Ceftazidime* / pharmacology
  • Drug Combinations*
  • Drug Resistance, Multiple, Bacterial / genetics
  • Humans
  • Klebsiella Infections* / drug therapy
  • Klebsiella Infections* / microbiology
  • Klebsiella pneumoniae* / drug effects
  • Klebsiella pneumoniae* / enzymology
  • Klebsiella pneumoniae* / genetics
  • Klebsiella pneumoniae* / pathogenicity
  • Male
  • Microbial Sensitivity Tests*
  • Plasmids / genetics
  • Virulence
  • Whole Genome Sequencing
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism

Substances

  • Ceftazidime
  • avibactam, ceftazidime drug combination
  • Azabicyclo Compounds
  • Drug Combinations
  • Anti-Bacterial Agents
  • Bacterial Proteins
  • beta-Lactamases
  • carbapenemase

Grants and funding

This work was supported by the Elite Medical Professionals Project of China-Japan Friendship Hospital [grant number ZRJY2023-QM32]; National Natural Science Foundation of China [grant number 82102456]; Chinese Academy of Medical Sciences CAMS Innovation Fund for Medical Sciences [grant number CIFMS 2021-I2M-1-048 and CIFMS 2021-I2M-1-030]; National High Level Hospital Clinical Research Funding [grant number 2022-NHLHCRF-LX-01].