FIG. 4.

EPI, NE, and indole affect E. coli O157:H7 attachment to HeLa cells. The relative change in EHEC attachment to HeLa cells after 3 h of exposure to EPI (50 μM), NE (50 μM), or indole (500 μM) was determined. Cell counts (means ± 1 standard deviation) are from duplicate LB agar plates and were generated from five HeLa cell culture wells. Control values are based on EHEC cell counts obtained without the addition of any molecule. Statistical significance was determined using a Student t test. *, P < 0.01; **, P < 0.005.