First isolation of an IMP-1 metallo-β-lactamase-producing Kluyvera ascorbata in Japan

J Glob Antimicrob Resist. 2020 Dec;23:228-231. doi: 10.1016/j.jgar.2020.09.026. Epub 2020 Oct 13.


Objectives: The emergence of carbapenemase-producing Enterobacterales has been increasing globally, causing growing concerns. Although Kluyvera ascorbata is not known as a metallo-β-lactamase (MBL)-producer, in the present study we isolated a K. ascorbata strain producing IMP-1 MBL from catheter-associated urine of a paediatric patient and performed whole-genome analysis to elucidate the features of this strain and the origin of IMP-1.

Methods: Carbapenemase production was confirmed by a modified carbapenemase inactivation method. Whole-genome sequencing was performed using NovaSeq 6000 and GridION. Conjugation ability was evaluated using Escherichia coli ML1410 by a broth mating assay.

Results: TheblaIMP-1 gene was located on a 149 316-bp transferable plasmid (pKATP2) and formed a class 1 integron structure. In addition, this plasmid had two types of repA genes as well as astA encoding a putative heat-stable enterotoxin. Comparison with other plasmids from Enterobacterales and Pseudomonas aeruginosa suggested that this plasmid might have originated by the integration of multiple plasmids. In addition, pKATP2 harboured conjugation-associated genes and was transferable.

Conclusion: This is the first report of MBL-producing K. ascorbata. Therefore, our findings suggest that species which do not typically produce MBL could acquire the corresponding genes, attracting attention as potential MBL-producing pathogens.

Keywords: Class 1 integron; IMP-1; Kluyvera ascorbata; Metallo-β-lactamase; Multidrug resistance.

MeSH terms

  • Anti-Bacterial Agents* / pharmacology
  • Child
  • Humans
  • Inosine Monophosphate*
  • Japan
  • Kluyvera
  • Microbial Sensitivity Tests
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • Inosine Monophosphate
  • beta-Lactamases

Supplementary concepts

  • Kluyvera ascorbata