Table 1.

E. coli O157 and non-O157 strains used for the study.

Strain*	Source	stx1	stx2	eae	hylA	References
E. coli O26:H11	cow, Ontario, Canada	−	+	+	+	Louie et al., 1998
E. coli O103:H2	cow, Ontario, Canada	+	+	+	+	Louie et al., 1998
E. coli O91:H21	Human, OH, USA	+	−	−	+	Ito et al., 1990
E. coli O157 NM	–, AL, USA	+	+	+	+	Fields et al., 1997
E. coli O157:H7 4554	cow, Japan	−	−	+	+	Feng et al., 2001
E. coli O157:H7 EDL933	human, USA	+	+	+	+	Perna et al., 2001

stx₁, a gene coding for Shiga toxin1, stx₂, a gene coding for Shiga toxin2, eae, a gene coding for intimin, and hylA, a gene coding for hemolysin. “+” and “−” indicate a gene was identified and not identified in a given E. coli strain, respectively. E. coli O157:H7 4554 is therefore stx negative.

−Indicates the source was not identified.

^*Adapted from Ma et al. (2014).