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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
04:25

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

Published on: February 24, 2014

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

Jin Yang Baek1, So Hyun Kim1, Cheol-In Kang2

  • 1Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea; Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.

International Journal of Medical Microbiology : IJMM
|August 26, 2018
PubMed

Insights

A new extensively drug-resistant (XDR) Streptococcus pneumoniae serotype 15A clone emerged through capsular switching. This finding is a significant public health concern, requiring careful monitoring in clinical settings.

Area of Science:

  • Microbiology
  • Genomics
  • Infectious Diseases

Background:

  • Extensively drug-resistant (XDR) Streptococcus pneumoniae poses a significant threat.
  • Serotype 15A XDR strains are emerging globally.
  • Previous identification of XDR serotype 11A in South Korea.

Purpose of the Study:

  • To investigate the genomic basis of a newly identified XDR Streptococcus pneumoniae serotype 15A isolate.
  • To compare the genome of the XDR 15A isolate with a previously identified XDR serotype 11A isolate.
  • To understand the mechanism of emergence of this new XDR clone.

Main Methods:

  • Whole-genome sequencing of XDR Streptococcus pneumoniae serotype 15A and 11A isolates.
  • Comparative genomic analysis focusing on the capsular polysaccharide (cps) locus.
  • Identification of sequence types (STs) and genetic variations.

Main Results:

  • The XDR 15A and XDR 11A isolates belonged to the same sequence type (ST8279).
  • Genomes were highly identical except for the capsular polysaccharide (cps) locus.
  • Evidence suggests capsular switching from serotype 11A to 15A via recombination at the cps locus.

Conclusions:

  • Capsular switching is a plausible mechanism for the emergence of new XDR Streptococcus pneumoniae clones.
  • The emergence of XDR ST8279 via capsular switching represents a significant public health concern.
  • Continuous genomic surveillance is crucial for monitoring and controlling the spread of drug-resistant bacteria.
Keywords:
Capsular switchingExtensively drug-resistantPneumococciST8279Serotype 11ASerotype 15A

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