Nonfimbrial Adhesin Mutants Reveal Divergent Escherichia coli O157:H7 Adherence Mechanisms on Human and Cattle Epithelial Cells

Figure 4

SS17 adherence mutant phenotypes on HEp-2 cells. Adherence of the parental strain and subsequent adherence-associated gene mutants of SS17 were tested for adherence quantitatively (a) and qualitatively (b). As the results show, SS17Δyfal, ΔeaeH, and Δeae are all deficient in adhering to HEp-2 cells compared to the parent SS17 strain. (a) Each bar is representative of four technical replicates per slide where 20 cells/spot were counted over two trials. The bar is the mean percentage of adherent bacteria (>10 or 1–10) per HEp-2 cell over the two trials. (b) Toluidine blue-stained slides are used to see the “adherence morphology” of SS17 to HEp-2 cells. The scale bar for each panel is set to 100 μm. Asterisks denote value <0.05.

(a)

(b)