Roles of oral bacteria in cardiovascular diseases - From molecular mechanisms to clinical cases: Cell-surface structures of novel serotype k streptococcus mutans strains and their correlation to virulence

Kazuhiko Nakano, Ryota Nomura, Michiyo Matsumoto, Takashi Ooshima

Research output: Contribution to journalArticle

49 Citations (Scopus)


Streptococcus mutans is generally known as a pathogen of dental caries, and it is also considered to cause bacteremia and infective endocarditis (IE). S. mutans was previously classified into 3 serotypes, c, e, and f, due to the different chemical compositions of the serotype-specific polysaccharides, which are composed of a rhamnose backbone and glucose side chains. We recently designated non-c/e/f serotype S. mutans strains as novel serotype k, which is characterized by a drastic reduction in the amount of the glucose side chain. A common biological feature of novel serotype-k strains is a lower level of cariogenicity due to alterations of several major cell surface protein antigens. As for virulence in blood, these strains survive in blood for a longer duration due to lower antigenicity, while the detection rate of all strains carrying the gene encoding collagen-binding adhesin has been shown to be high. Furthermore, molecular biological analyses of infected heart valve specimens obtained from IE patients revealed a high detection rate of serotype-k S. mutans. Together, these findings suggest that serotype-k S. mutans strains show low cariogenicity but high virulence in blood as compared to the other serotypes, due to alterations of several cell surface structures.

Original languageEnglish
Pages (from-to)120-125
Number of pages6
JournalJournal of Pharmacological Sciences
Issue number2
Publication statusPublished - Jun 15 2010



  • Cell-surface antigen
  • Infective endocarditis
  • Oral bacteria
  • Serotype, bacteremia
  • Streptococcus mutans

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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