Two highly divergent lineages of exfoliative toxin B-encoding plasmids revealed in impetigo strains of Staphylococcus aureus

Int J Med Microbiol. 2017 Sep;307(6):291-296. doi: 10.1016/j.ijmm.2017.05.005. Epub 2017 May 29.

Abstract

Exfoliative toxin B (ETB) encoded by some large plasmids plays a crucial role in epidermolytic diseases caused by Staphylococcus aureus. We have found as yet unknown types of etb gene-positive plasmids isolated from a set of impetigo strains implicated in outbreaks of pemphigus neonatorum in Czech maternity hospitals. Plasmids from the strains of clonal complex CC121 were related to archetypal plasmid pETBTY4. Sharing a 33-kb core sequence including virulence genes for ETB, EDIN C, and lantibiotics, they were assigned to a stand-alone lineage, named pETBTY4-based plasmids. Differing from each other in the content of variable DNA regions, they formed four sequence types. In addition to them, a novel unique plasmid pETB608 isolated from a strain of ST130 was described. Carrying conjugative cluster genes, as well as new variants of etb and edinA genes, pETB608 could be regarded as a source of a new lineage of ETB plasmids. We have designed a helpful detection assay, which facilitates the precise identification of the all described types of ETB plasmids.

Keywords: Bullous impetigo; ETB plasmids; Exfoliative toxin B; Phylogeny; Staphylococcus aureus.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacteriocins / genetics
  • Czech Republic / epidemiology
  • DNA, Bacterial / genetics
  • Dermotoxins / genetics*
  • Exfoliatins / genetics*
  • Humans
  • Impetigo / epidemiology
  • Impetigo / microbiology*
  • Pemphigus / epidemiology
  • Pemphigus / microbiology
  • Phylogeny
  • Plasmids / genetics*
  • Plasmids / isolation & purification
  • Staphylococcus aureus / classification
  • Staphylococcus aureus / genetics*
  • Virulence / genetics
  • Whole Genome Sequencing

Substances

  • Bacterial Proteins
  • Bacteriocins
  • DNA, Bacterial
  • Dermotoxins
  • Exfoliatins