FIG 6.
Virulence phenotypes of D39 and D39AAA. Groups of 16 mice were infected intranasally with 107 CFU of the indicated strain. At 24 h, mice were euthanized, and the numbers of pneumococci isolated from the nasal tissue (A), ears (B), lungs (C), and blood (D) were enumerated. Viable counts (total CFU per tissue or CFU per ml blood) are shown for each mouse in each niche; the horizontal bars indicate the geometric mean (GM) CFU for each group; the dotted line indicates the threshold of detection. The significance of the differences in GM bacterial load between groups was analyzed using unpaired t tests; *, P < 0.05; **, P < 0.01; ***, P < 0.001.