Distinct evolutionary dynamics of horizontal gene transfer in drug resistant and virulent clones of Klebsiella pneumoniae

PLoS Genet. 2019 Apr 15;15(4):e1008114. doi: 10.1371/journal.pgen.1008114. eCollection 2019 Apr.

Abstract

Klebsiella pneumoniae has emerged as an important cause of two distinct public health threats: multi-drug resistant (MDR) healthcare-associated infections and drug susceptible community-acquired invasive infections. These pathotypes are generally associated with two distinct subsets of K. pneumoniae lineages or 'clones' that are distinguished by the presence of acquired resistance genes and several key virulence loci. Genomic evolutionary analyses of the most notorious MDR and invasive community-associated ('hypervirulent') clones indicate differences in terms of chromosomal recombination dynamics and capsule polysaccharide diversity, but it remains unclear if these differences represent generalised trends. Here we leverage a collection of >2200 K. pneumoniae genomes to identify 28 common clones (n ≥ 10 genomes each), and perform the first genomic evolutionary comparison. Eight MDR and 6 hypervirulent clones were identified on the basis of acquired resistance and virulence gene prevalence. Chromosomal recombination, surface polysaccharide locus diversity, pan-genome, plasmid and phage dynamics were characterised and compared. The data showed that MDR clones were highly diverse, with frequent chromosomal recombination generating extensive surface polysaccharide locus diversity. Additional pan-genome diversity was driven by frequent acquisition/loss of both plasmids and phage. In contrast, chromosomal recombination was rare in the hypervirulent clones, which also showed a significant reduction in pan-genome diversity, largely driven by a reduction in plasmid diversity. Hence the data indicate that hypervirulent clones may be subject to some sort of constraint for horizontal gene transfer that does not apply to the MDR clones. Our findings are relevant for understanding the risk of emergence of individual K. pneumoniae strains carrying both virulence and acquired resistance genes, which have been increasingly reported and cause highly virulent infections that are extremely difficult to treat. Specifically, our data indicate that MDR clones pose the greatest risk, because they are more likely to acquire virulence genes than hypervirulent clones are to acquire resistance genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Capsules / genetics
  • Bacterial Capsules / metabolism
  • Bacteriophages / genetics
  • Cross Infection / drug therapy
  • Cross Infection / microbiology
  • Drug Resistance, Bacterial / genetics*
  • Drug Resistance, Multiple, Bacterial / genetics
  • Evolution, Molecular*
  • Gene Transfer, Horizontal*
  • Genetic Variation
  • Genome, Bacterial
  • Humans
  • Klebsiella Infections / drug therapy
  • Klebsiella Infections / microbiology
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / genetics*
  • Klebsiella pneumoniae / pathogenicity
  • Lipopolysaccharides / biosynthesis
  • Lipopolysaccharides / genetics
  • Models, Genetic
  • Plasmids / genetics
  • Virulence / genetics*

Substances

  • Lipopolysaccharides

Grants and funding

This work was supported by a Viertel Foundation of Australia Senior Medical Research Fellowship to KEH, the Bill and Melinda Gates Foundation, Seattle (OPP1175797), and the University of Melbourne. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.