Fig 4. Adhesion and invasion properties of E. coli strains.

PS cells were incubated for 3 h with the indicated strains at a MOI of 10 in stimulation medium (black bars) or fresh milk (white bars). Cells were then washed twice with HBSS. A) cells were lysed by the addition of 0.2% Triton X-100 and bacteria were counted in the supernatant. B) Growth medium with gentamicin was added for 30 minutes, cells were then washed with DPBS, lysed by the addition of 0.2% Triton X-100 and bacteria were counted in the supernatant. Data presented are mean values and SD obtained from 3 independent experiments performed in duplicates. * indicates statistical significance (P < 0.05). p-values were calculated using exact permutation tests after global comparison using a Kruskal and Wallis test.