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.
Nakano
Kazuhiko
K
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
Nomura
Ryota
R
Matsumoto
Michiyo
M
Ooshima
Takashi
T
D016470:Bacteremia / Q000382:microbiology; D001769:Blood / Q000382:microbiology; D002319:Cardiovascular System / Q000382:microbiology; D004697:Endocarditis, Bacterial / Q000382:microbiology*; D005947:Glucose; D006801:Humans; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D012210:Rhamnose; D012703:Serotyping; D013290:Streptococcal Infections; D013295:Streptococcus mutans / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence
D011135:Polysaccharides, Bacterial; D005947:Glucose; D012210:Rhamnose