FIG. 3.

Effect of E. coli culture supernatants on Vero-d2EGFP fluorescence. Vero-d2EGFP cells were exposed to Ham's F-12 medium containing 10-fold dilutions of culture supernatant from Stx1- and Stx2-producing E. coli O157 strain RM1697, non-Stx-producing E. coli O157 strain RM4876, or nonpathogenic E. coli strain RM5034. After 16 h of incubation, the fluorescence output was recorded with a plate reader. The averages ± standard deviations of three independent experiments with duplicate samples for each condition are shown.