Figure 6. UppS^UN confers greater susceptibility to antimicrobials and decreased virulence in a murine model of pneumonia in an ΔmlaF background.

(A to D) Antimicrobial susceptibility of VU and UN WT and mutant strains was determined by a disk-diffusion assay measuring the zone of clearance. Data are representative of 3 experiments. n=3, data are mean ± SEM. Significance is by one-way ANOVA with Tukey’s multiple comparisons. Limit of detection (LOD) = 6 mm. (E) Lysozyme susceptibility of VU and UN WT and mutant strains at 12 h during growth with a final concentration of 1 mg/mL lysozyme. n=3, data are means ± SEM. Significance is by one-way ANOVA with Tukey’s multiple comparisons. (F) VU and UN WT and ΔmlaF strains with the intrinsic or opposite uppS allele were used to intranasally infect C57BL/6 mice in a 1:1 WT:mutant ratio. After 48 h post infection, the lungs were harvested and bacterial burdens were enumerated. n=5, normality of log₁₀-transformed competitive index data was determined by the Kolmogorov-Smirnov test and significance competitive index was determined by a one sample t test compared to 0. * p < 0.05, ** p <0.01, *** p < 0.001, **** p < 0.0001.