Emergence of an Australian-like pstS-null vancomycin resistant Enterococcus faecium clone in Scotland

PLoS One. 2019 Jun 13;14(6):e0218185. doi: 10.1371/journal.pone.0218185. eCollection 2019.

Abstract

Multi-locus sequencing typing (MLST) is widely used to monitor the phylogeny of microbial outbreaks. However, several strains of vancomycin-resistant Enterococcus faecium (VREfm) with a missing MLST locus (pstS) have recently emerged in Australia, with a few cases also reported in England. Here, we identified similarly distinct strains circulating in two neighbouring hospitals in Scotland. Whole genome sequencing of five VREfm strains isolated from these hospitals identified four pstS-null strains in both hospitals, while the fifth was multi-locus sequence type (ST) 262, which is the first documented in the UK. All five Scottish isolates had an insertion in the tetM gene, which is associated with increased susceptibility to tetracyclines, providing no other tetracycline-resistant gene is present. Such an insertion, which encompasses a dfrG gene and two currently uncharacterised genes, was additionally identified in all tested vanA-type pstS-null VREfm strains (5 English and 68 Australian). Phylogenetic comparison with other VREfm genomes indicates that the four pstS-null Scottish isolates sequenced in this study are more closely related to pstS-null strains from Australia rather than the English pstS-null isolates. Given how rapidly such pstS-null strains have expanded in Australia, the emergence of this clone in Scotland raises concerns for a potential outbreak.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / therapeutic use
  • Australia
  • Cross Infection / drug therapy
  • Cross Infection / genetics
  • Cross Infection / microbiology
  • Disease Outbreaks
  • England
  • Enterococcus faecium / drug effects*
  • Enterococcus faecium / genetics*
  • Genotype
  • Gram-Positive Bacterial Infections / drug therapy
  • Gram-Positive Bacterial Infections / genetics
  • Gram-Positive Bacterial Infections / microbiology
  • Humans
  • Microbial Sensitivity Tests / methods
  • Multilocus Sequence Typing / methods
  • Phylogeny
  • Scotland
  • Vancomycin / therapeutic use*
  • Vancomycin-Resistant Enterococci / genetics*

Substances

  • Anti-Bacterial Agents
  • Vancomycin