FIG 4.

Colibactin genes influence the degree of GI tract colonization and blood and organ dissemination of E. coli A192PP in the susceptible P2 neonatal rat. Tissues were removed 24 h after colonization and CFU/g of tissue determined by plating on MacConkey agar. E. coli A192PP colonies were detected using K1-specific bacteriophage; mutants were selected on medium containing 50 μg/ml kanamycin. SI, small intestine. For panel A, strain A192PP n = 18 and strain A192PPΔclbA::kan n = 18. For panel B, strain A192PP n = 17 and strain A192PPΔclbP::kan n = 17 (Student's t test; ns, nonsignificant; *, P < 0.05; **, P < 0.01; ***, P < 0.001).