Fig 1. Intestinal colonization after a single oral challenge with 10⁷ CFU of UPEC strain 536.

Fecal pellets were individually collected from C3H/HeOuJ (A) or C57BL6/J (B) mice every day or every other day after oral challenge. E. coli strain 536 CFUs were enumerated in the feces by serial dilution on MacConkey+streptomycin (30 μg/mL) agar plates and expressed as log₁₀ (CFU/g feces). Mean bacterial loads were not significantly different over time (Fig 1A and 1B, one-way ANOVA with Bonferroni’s correction for multiple comparisons). C: Some C3H/HeOuJ mice provided by Jackson Laboratory were colonized by Enterobacteriaceae and others were not. Here, fecal counts on days 1 to 8, from Fig 1A are pooled, and represented according to the presence or absence of Enterobacteriaceae prior to oral gavage with E. coli strain 536. The line indicates a significant difference with p<0.01 (t-test). Bars and whiskers represent means ± standard deviation (Fig 1A and B) or median and interquartile range (Fig 1C).