Genetic features of livestock-associated Staphylococcus aureus ST9 isolates from Chinese pigs that carry the lsa(E) gene for quinupristin/dalfopristin resistance

Int J Med Microbiol. 2016 Dec;306(8):722-729. doi: 10.1016/j.ijmm.2016.08.001. Epub 2016 Aug 10.


Whole-genome sequencing (WGS) was used to investigate the genetic features of the recently identified lsa(E) gene in porcine S. aureus ST9 isolates. Three quinupristin/dalfopristin-resistant isolates harboring the lsa(E) gene (two MRSA and one MSSA) were sequenced. Phylogenetic analysis of 184S. aureus genomes showed that ST9 porcine isolates belong to a distinct sequence cluster. Further analysis showed that all isolates were deficient in the recently described type IV restriction-modification system and SCCmec type XII was identified in the two MRSA isolates, which included a rare class C2 mec gene complex. A 24kb ΨSCC fragment was found in the MRSA and MSSA isolates sharing 99% nucleotide sequence homology with the ΨSCCJCSC6690 (O-2) element of a ST9 MRSA isolate from Thailand (accession number AB705453). Comparison of these ST9 isolates with 181 publically available S. aureus genomes identified 24 genes present in all (100%) ST9 isolates, that were absent from the most closely related human isolate. Our analysis suggests that the sequenced quinupristin/dalfopristin-resistant ST9 lineage represent a reservoir of mobile genetic elements associated with resistance and virulence features.

Keywords: ABC transporters; Livestock-associated; Quinupristin/dalfopristin; Resistance; ST9; Staphylococcus aureus.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Cluster Analysis
  • DNA Restriction-Modification Enzymes / deficiency
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial / genetics*
  • Gene Order
  • Genes, Bacterial*
  • Genome, Bacterial
  • Genotype
  • Interspersed Repetitive Sequences
  • Molecular Typing
  • Phylogeny
  • Sequence Analysis, DNA
  • Sequence Homology
  • Staphylococcus aureus / classification
  • Staphylococcus aureus / genetics*
  • Staphylococcus aureus / isolation & purification*
  • Swine / microbiology*
  • Thailand
  • Virginiamycin / pharmacology*


  • Anti-Bacterial Agents
  • DNA Restriction-Modification Enzymes
  • DNA, Bacterial
  • Virginiamycin
  • quinupristin-dalfopristin