FIG. 6.

amrZ mutants exhibit an in vivo virulence defect. (A) Wild-type strain PAO1 and strain WFPA205 (amrZ::tet) were used to intranasally inoculate 6-week-old C57BL/6 mice with 1 × 10⁸ bacteria. At the indicated time points (hpi), lungs were aseptically harvested, and the bacteria were enumerated. Each symbol indicates an individual mouse (n = 5 for each group per time point). Gray bars indicate averages along with standard deviations (*, P = 0.036). (B) Mice (n = 15) were assessed for bacterial colonization (>10⁴ bacteria recovered from the lungs), bacteremia (bacteria recovered from the blood), or death (requiring euthanasia due to severe disease symptoms) at 12 hpi. (C) Strains PAO1 and WFPA205 were coinoculated at a 1:1 ratio (total of 10⁸ bacteria). At 24 hpi, lungs and blood were harvested, and bacterial counts were determined. The competitive index from the lungs is plotted for each mouse (n = 13) and for those that showed evidence of bacteremia (n = 8).