FIG 1.

Deletion of fnr attenuates virulence in the mouse model of UTI by UPEC CFT073. The WT and fnr mutant strains, the wild-type strain containing the empty vector (pGEN-MCS), and the mutant strain containing the complementation plasmid (pGEN-fnr) were mixed in a 1:1 ratio and approximately 2 × 10⁹ CFU was transurethrally inoculated into female mice. Two days after infection, the mice were sacrificed and their bladders (A) and kidneys (B) were aseptically removed. WT and fnr mutant bacteria were recovered by plating homogenized tissue samples on LB medium or LB medium containing kanamycin, and CFU counts were determined. The wild-type strain containing the empty vector (pGEN-MCS) and the mutant strain containing the complementation plasmid (pGEN-fnr) were recovered by plating homogenized tissue samples on LB medium with ampicillin or LB medium with both ampicillin and kanamycin. Each dot represents the log₁₀ number of CFU/g in the bladder or kidney from an individual animal, and the detection limit was 1,000 CFU/g. Bars indicate the median log₁₀ number of CFU/g. A two-tailed Wilcoxon matched-pairs test was performed, and the difference in the colonization levels of the WT and mutants was considered statistically significant if P was <0.05.