Recognition of specific sialoglycan structures by oral streptococci impacts the severity of endocardial infection

This data set was used to tabulate the relative virulence of 3 strains of Streptococcus gordonii (M99, PS3515 and PS3516) in animal (rat) models of infective endocarditis. In brief, a sterile polyethylene catheter was surgically placed across the aortic valve of each animal, such that the tip was positioned in the left ventricle, and left in place throughout the experiment. Three days post-catheterization rats were infected IV with an innoculum of either 1 x 10e5 CFU of single S. gordonii strains, or with 2 x 10e5 CFU of a pair of strains at a 1:1 ratio, as indicated. All cardiac vegetations, as well as samples of the kidneys and spleens, were harvested, weighed, homogenized in saline, serially diluted, and plated onto agar plates to determine the number of bacteria in the homogenized tissues. For the competition studies, bacterial colonies were plated onto medium containing spectinomycin, in order to determine the CFU/g of M99 and the isogenic variant strain. The number of bacteria within tissues was expressed as the log10 CFU per gram of tissue.Differences in the initial in vivo adherence of these strains to the endocardium were assessed using the single strain infection model described above, except that rats were infected with either 10e8 or 10e7 CFU (levels determined to be at or above the level of detection, and below the level of saturated binding). At 1 h post-infection, blood samples were obtained, animals were sacrificed and the cardiac vegetations harvested for quantitative culture.