The intersection of capsule gene expression, hypermucoviscosity and hypervirulence in Klebsiella pneumoniae

Curr Opin Microbiol. 2020 Apr;54:95-102. doi: 10.1016/j.mib.2020.01.006. Epub 2020 Feb 12.


For ∼30 years, two distinct groups of clinical isolates of Klebsiella pneumoniae have been recognized. Classical strains (cKp) are typically isolated from patients with some degree of immunocompromise and are not virulent in mouse models of infection whereas hypervirulent strains (hvKp) are associated with community acquired invasive infections and are highly virulent in mouse models of infection. Hyperproduction of capsule and a hypermucoviscous colony phenotype have been strongly associated with the hypervirulence of hvKp strains. Recent studies have begun to elucidate the relationship between capsule gene expression, hypermucoviscosity and hypervirulence. Additionally, genes associated with hyperproduction of capsule and hypermucoviscosity in hvKp strains have been identified in a few cKp isolates. However, it is not clear how the acquisition of these genes impacts the virulence of cKp isolates. A better understanding of the potential risks of these strains is particularly important given that many of them are resistant to multiple antibiotics, including carbapenems.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Bacterial Capsules / genetics*
  • Bacterial Capsules / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial
  • Humans
  • Klebsiella Infections / microbiology*
  • Klebsiella pneumoniae / cytology
  • Klebsiella pneumoniae / genetics*
  • Klebsiella pneumoniae / pathogenicity*
  • Mice
  • Mutation
  • Virulence / genetics
  • Virulence Factors / genetics*
  • Virulence Factors / metabolism


  • Bacterial Proteins
  • Virulence Factors