Fig. 3

Detection of S. pneumoniae with Spn-FLUO in mouse lung specimens. Balb/c mice were intranasally inoculated with strain TIGR4 or isogenic mutant ΔspxBΔlctO and euthanized when deemed moribund, or after 96 h post-infection. Lungs were collected and homogenized. (A) Lung homogenates were diluted and plated to obtain the bacterial density. (B) Aliquots of lung homogenate were stained with Spn-FLUO and scored for the presence of pneumococci. Micrographs were obtained with a fluorescence microscope in the green channel. The top panel shows a representative specimen scored “+” with arrows pointing out S. pneumoniae, while the bottom panel shows a representative specimen that scored “+++”. (C) The density in the graphic was grouped according to the semiquantitative detection of S. pneumoniae with Spn-FLUO. Statistical significance of differences in bacterial density were determined using Student’s t-test (A) or one-way ANOVA followed by Dunnett’s multiple comparisons test (C). *p = 0.027, **p = 0.0088, ***p = 0.0007