Roles of RyhB and Fur in colonization of the mouse urinary tract at 6 h postinfection. CBA/J mice were infected with either CFT073 or one of its mutants (ΔryhB, Δfur, or ΔryhB Δfur), and bladders and kidneys were aseptically removed at 6 h p.i. Results are presented as log10 CFU g−1. Each data point represents a sample from an individual mouse, and horizontal bars indicate the median values. Each kidney was sampled separately. The Mann-Whitney test was used to determine the statistical differences. The dashed line represents the limit of detection of bacterial numbers. NS, not significant.