FIG. 3.

Caco-2 attachment efficacies for E. coli O157:H7 isolates representing genetically diverse PFGE subtypes and an E. coli O157:H7 isolate known to have caused an outbreak of food-borne illness, which was included as a reference. The data are expressed as the percentage of adherent E. coli O157:H7 cells recovered from each well. The PFGE subtype or subtype category is indicated on the x axis, while the percent attachment is indicated on the y axis. The bars indicate the least-squares means for attachment efficacies obtained for at least two strains for each subtype category (except for the 6- and >7-band bars, where only one E. coli O157:H7 strain was assayed for each category) for three independent experiments. The error bars indicate the standard errors calculated for each least-squares mean. Bars that do not contain the same letter are significantly different (P < 0.05). The outbreak strain was not included in the analysis, but data for this strain are included for reference. Dif., differences.