Table 1. List of O157:H7 strains used in this study.

Straina	Alias	O157:H7 Cladeb	SGb	Shiga toxin Complement	Clinical presentation, origin and reference
TW08264	Sakai	1	1	stx1, stx2	Unknown, 1996 outbreak, Sakai, Japan [40]
TW08612	EK4	1	1	stx1, stx2	HUSc, 2001, WA, USA [41]
TW04863	93-111	2	9	stx1, stx2	Diarrhea, 1993 outbreak, northwest USA [42]
TW11029		2	NDd	stx2	HCe, 2002, MI, USA
TW02302	EDL933	3	12	stx1, stx2	HC, 1982 outbreak, MI and OR, USA [43]
TW09178	MI03-9	7	29	stx1, stx2c
TW14359	MI06-63	8	30	stx2, stx2c	HC, 2006 outbreak, western USA [11]
TW00885	EC508	8	31	stx2, stx2c	HUS, 1984, NC, USA [28]
TW02883	E32511	8	31	stx2, stx2c	HUS, CDC [29, 44]
TW14313	MI06-31	8	33	stx2	HUS, 2006, MI, USA
TW08609	EK1	8	33	stx2	Diarrhea, 1999, WA, USA [41]

^aAll strains were acquired from the STEC Center at Michigan State University.

^bBased on the work of Manning et al. [11]. SG is single nucleotide polymorphism (SNP) genotype.

^cHemolytic uremic syndrome (HUS).

^dNot determined (ND).

^eHemorrhagic colitis (HC).