Organ lesion scores for groups of chickens 24 h after infection with APEC outbreak strain IMT5155 (gray bar), nonpathogenic control strain IMT11327 (open bar), Afecal E. coli strains (dotted bars), and Aenviron E. coli strains (striped bars). *, P ≤ 0.05; **, P ≤ 0.02; ***, P ≤ 0.001. IMT, Institut für Mikrobiologie und Tierseuchen (Institute of Microbiology and Epizootics).