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Comparative Genomic Analyses of Streptococcus pseudopneumoniae Provide Insight into Virulence and Commensalism

Dea Shahinas1, Christina S Thornton, Gurdip Singh Tamber

  • 1Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.

Plos One
|July 11, 2013
PubMed

Insights

Streptococcus pseudopneumoniae, a newly identified bacterium, shares traits with both Streptococcus pneumoniae and Streptococcus mitis. Its genome analysis reveals unique features and potential virulence factors, suggesting a role in disease and antibiotic resistance.

Area of Science:

  • Microbiology
  • Genomics
  • Bacterial Pathogenesis

Background:

  • Streptococcus pseudopneumoniae (SPPN) is a recently identified species within the viridans group streptococci (VGS).
  • SPPN is frequently isolated from patients with underlying conditions like chronic obstructive pulmonary disease, though its pathogenic potential is unclear.
  • Distinguishing SPPN from S. pneumoniae and S. mitis involves phenotypic tests such as optochin resistance, bile insolubility, and absence of a capsule.

Purpose of the Study:

  • To perform comparative genomics to identify similarities and differences between S. pseudopneumoniae IS7493, S. pneumoniae, and S. mitis.
  • To elucidate the phylogenetic position and potential pathogenic mechanisms of S. pseudopneumoniae.

Main Methods:

  • Comparative genomics analysis of the S. pseudopneumoniae IS7493 genome.
  • Examination of gene content, including loci for competence, iron transport, pneumolysin, and antimicrobial resistance.

Main Results:

  • The genome structure of S. pseudopneumoniae IS7493 closely resembles S. pneumoniae R6, with evidence of recombination.
  • Numerous unique genes distinguish S. pseudopneumoniae from other streptococci.
  • Presence of competence, iron transport, pneumolysin, and antimicrobial resistance loci were identified.

Conclusions:

  • S. pseudopneumoniae occupies an intermediate phylogenetic position between S. pneumoniae and S. mitis.
  • The identified virulence factors and antibiotic resistance mechanisms suggest potential for pathogenicity and contribution to rising VGS antibiotic resistance.

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