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Evolution and transmission potential of iuc3-positive virulence plasmids in hypervirulent Klebsiella pneumoniae

Jiayun Wang1, Xing Ji2, Pilar García3

  • 1Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210040, China.

Microbiological Research
|June 8, 2025
PubMed

Insights

Hypervirulent Klebsiella pneumoniae strains carrying the iuc3 operon were identified in cows. These strains exhibit enhanced virulence and can spread through plasmids, posing a public health risk requiring monitoring in animals and humans.

Area of Science:

  • Microbiology
  • Genetics
  • Public Health

Background:

  • Hypervirulent Klebsiella pneumoniae (hvKP) poses a global health threat.
  • The iucABCD operon, encoding aerobactin, is a key biomarker for hvKP.
  • Understanding the role of specific iuc types, like iuc3, is crucial for hvKP surveillance.

Purpose of the Study:

  • Characterize iuc3-positive K. pneumoniae from diseased cows as hvKP.
  • Elucidate the contribution of iuc3-positive plasmids to hypervirulence.
  • Investigate the evolutionary pathways and dissemination risks of iuc3-positive plasmids.

Main Methods:

  • Isolating and characterizing K. pneumoniae from cow milk samples.
  • Phenotypic analysis of hypervirulence in animal models.
  • Bioinformatic analysis of public databases (NCBI) for strain distribution and evolution.
  • Plasmid conjugation and stability experiments.

Main Results:

  • Eight iuc3-positive K. pneumoniae isolates from cows exhibited hypervirulence.
  • These iuc3 operons were located on T4SS-bearing plasmids.
  • iuc3-positive strains are distributed across animal, food, and human sources, with independent evolution from iuc1-type hvKP.
  • iuc3-bearing plasmids showed high conjugative ability, low fitness cost, and could replace iuc1 plasmids.
  • Fusion with IncX3-blaNDM-5 plasmids created carbapenem-resistant hvKP with strong in vivo dissemination.

Conclusions:

  • iuc3-positive K. pneumoniae strains from animals represent a significant hvKP reservoir.
  • iuc3-positive plasmids contribute to hypervirulence and possess efficient dissemination mechanisms.
  • Long-term monitoring of iuc3-positive plasmids in both animal and human isolates is essential for public health surveillance.
Keywords:
ConjugationGenomic evolutionHvKPKlebsiella pneumoniaePlasmid fusioniucABCD

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