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

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. © 2010 the japanese pharmacological society.