Figure 2. Murine colonization model: persistence of three antibiotic resistant S. pneumoniae clones in mouse tissues.

Mice were intranasally inoculated with 10⁸ CFU of the non-PCV7 clones (6A, 15A or 19A) or the control strain (D39). At days 2, 7, 14, and 21 after inoculation, CFU counting was performed in the nasopharynx, olfactory bulbs, brain, lungs, and middle ear. Each bar represents the mean of the total CFU recovered (Log₁₀) throughout the 21-day experiment for each strain in 10-24 mice ± SEM. (A) nasopharynx, (B) lungs, (C) olfactory bulbs, (D) brain, (E) middle ear and (F) blood. The 0 value on the Y-axis represents the absence of detectable CFUs. The asterisks indicates significant differences, * p<0.05, ** p<0.01 and *** p<0.001 according to 2-tailed Mann-Whitney U test.