Emergence of an extensively drug-resistant (XDR) Streptococcus pneumoniae serotype 15A by capsular switching

Int J Med Microbiol. 2018 Dec;308(8):986-989. doi: 10.1016/j.ijmm.2018.08.004. Epub 2018 Aug 16.


Recently, we have identified an extensively drug-resistant (XDR) Streptococcus pneumoniae serotype 15A isolate from a patient with bacterial meningitis. It belonged to sequence type 8279 (ST8279), a clone identified as XDR serotype 11A isolated in South Korea. We obtained and compared the genome sequences of an XDR 15A and an XDR 11A isolate. The genomes of two XDR isolates were highly identical, except for the capsular polysaccharide (cps) locus and another small region. Capsular switching from 11A to 15A may have occurred via recombination of the cps locus. The emergence of a new XDR clone via capsular switching would be a great concern for public health and in clinical settings.

Keywords: Capsular switching; Extensively drug-resistant; Pneumococci; ST8279; Serotype 11A; Serotype 15A.

MeSH terms

  • Aged
  • Arthritis, Infectious / blood
  • Arthritis, Infectious / microbiology*
  • Bacterial Capsules / genetics*
  • Communicable Diseases, Emerging / microbiology*
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Female
  • Genome, Bacterial / genetics
  • Humans
  • Meningitis, Pneumococcal / blood
  • Meningitis, Pneumococcal / microbiology*
  • Recombination, Genetic
  • Republic of Korea
  • Serogroup
  • Shoulder / microbiology*
  • Spondylitis / blood
  • Spondylitis / microbiology
  • Streptococcus pneumoniae / genetics*
  • Streptococcus pneumoniae / isolation & purification
  • Whole Genome Sequencing