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Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria
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Virulence among different types of hypervirulent Klebsiella pneumoniae with multi-locus sequence type (MLST)-11,

Tsui-Chin Wang1, Jung-Chung Lin2, Jen-Chang Chang1

  • 1National Institute of Infectious Disease and Vaccinology, National Health Research Institute, Zhunan, Miaoli, Taiwan.

Gut Pathogens
|June 22, 2021
PubMed
Abstract

Insights

Hypervirulent Klebsiella pneumoniae (HvKp) strains, specifically ST11 and serotype K1/K2, exhibit distinct virulence levels. Serotype K1/K2 strains demonstrate significantly higher virulence and mouse lethality compared to ST11 isolates in comparative studies.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacteriology

Background:

  • Two main types of hypervirulent Klebsiella pneumoniae (HvKp), ST11 and serotype K1/K2, are recognized.
  • Previous studies described these strains as HvKp but did not compare their virulence directly.

Purpose of the Study:

  • To compare the virulence of ST11 and serotype K1/K2 HvKp strains.
  • To elucidate the differences in virulence using in vitro and in vivo models.

Main Methods:

  • Twenty-nine K. pneumoniae isolates (17 ST11, 6 K1, 6 K2) were analyzed.
  • Phenotypic virulence tests, PCR for virulence genes, serum resistance, and phagocytosis assays were performed.
  • Median lethal dose (LD50) in mice was determined after intraperitoneal injection.

Main Results:

  • ST11 isolates showed lower serum and phagocytic resistance than K1/K2 strains.
  • ST11 isolates did not cause lethality in mice (LD50 > 10^7 CFU), while K1/K2 strains had LD50 ≤ 10^3 CFU.
  • Aerobactin or capsule gene knockouts reduced LD50, with capsule mutants showing a more significant decrease.

Conclusions:

  • Significant virulence differences exist between ST11 and K1/K2 HvKp strains.
  • The designation 'HvKp' may require refinement based on animal study data to avoid confusion.
  • Virulence assessment should be relative, especially in comparative studies.
Keywords:
HypervirulenceKlebsiella pneumoniaMLSTSerotype

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