FIG 7 .
Bacterial burden of wild-type D39 and Δrgg (SP68) and Over-EXP (SP44) mutant strains in a mouse early lung infection model. Each dot represents results for a single mouse, and bars represent the mean and the standard error of the mean of each group. Mice were inoculated intranasally with 5 × 106 CFU in 50 µl of 1× PBS and killed after 24 h. Recovery of samples took place immediately after death, and all washes were placed at 4°C for dilution and plating. (A) Nasal cavity wash. **, P < 0.01; *, P < 0.05. (B) BALF. (C) Mixed-infection assay with D39 and Over-EXP. The first set was recovered from nasal wash. Each point represents results for a single mouse, and bars show the median CI of the group. The second and third sets show bacteria recovered from BALF and mashed lungs, respectively. The y axis shows the ratio of the bacterial counts recovered to the inoculum. A ratio of >1 indicates that the overexpression strain was predominant, while a ratio of 0 to 1 indicates that D39 was recovered in higher numbers. *, P < 0.05.