title: Role of the serine-rich surface glycoprotein GspB of Streptococcus gordonii in the pathogenesis of infective endocarditis.
abstract: The direct binding of bacteria to platelets is a central interaction in the pathogenesis of infective endocarditis. GspB is a serine-rich, cell wall glycoprotein of Streptococcus gordonii that mediates the binding of this organism to human platelets in vitro. To assess the contribution of this adhesin to the pathogenesis of endocarditis, we compared the virulence of S. gordonii M99 (which expresses GspB) with an isogenic, gspB mutant (PS846) in two rat models of endovascular infection. In the first group of experiments, animals were infected intravenously with M99 or PS846, and sacrificed 72 h later, to assess levels of bacteria within cardiac vegetations, kidneys, and spleens. When inoculated with 10(5)CFU, rats infected with PS846 had significantly lower densities of organisms within vegetations (mean: 3.84 log(10)CFU/g) as compared with M99-infected rats (6.67 log(10)CFU/g; P<0.001). Marked differences were also seen in rats co-infected with M99 and PS846, at a 1:1 ratio. While M99 was found at high levels within vegetations, kidneys and spleens (mean log(10)CFU/g: 6.62, 5.07 and 4.18, respectively) PS846 was not detected within these tissues. Thus, platelet binding by GspB appears to be a major interaction in the pathogenesis of endocarditis due to S. gordonii.
authors.affiliation: Department of Medicine, Harbor-UCLA Medical Center, 1000W Carson Street, Building RB2, Torrance, CA 90502, USA.
authors.forename: Yan Q
authors.initials: YQ
authors.lastname: Xiong
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Bensing
authors.forename: Arnold S
authors.initials: AS
authors.lastname: Bayer
authors.forename: Henry F
authors.initials: HF
authors.lastname: Chambers
authors.forename: Paul M
authors.initials: PM
authors.lastname: Sullam
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001792:Blood Platelets / Q000382:microbiology; D004697:Endocarditis, Bacterial / Q000382:microbiology*; D004699:Endocardium / Q000382:microbiology; D005260:Female; D006801:Humans; D007668:Kidney / Q000382:microbiology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism*; D013154:Spleen / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology*; D054773:Streptococcus gordonii / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D012694:Serine