TABLE 1.

Intimins from different organisms have been classified into several different subtypes based on antigenic and sequence divergences in the C-terminal domain of the protein (1, 45). The designations of strain E2348/69 intimin as α and strain EDL933 intimin as γ were published previously (1, 45). Intimin from strain 86-24 was classified as γ based on sequence identity with the intimin from strain EDL933. We have listed the intimin from strain H19 as β because the published sequence encoding the C-terminal region of this protein is identical to the published sequences of β intimins from two other strains (3, 45). Determination of the intimin subtypes for strains 97-3250, 85-3007, 95-3208, and 97-3256 was accomplished by PCR analysis; in the assay, the two O111:NM strains were demonstrated to have the eae gene but the sequence did not fall into α, β, or γ subtypes (54a). Thus, the intimin subtypes of the O111:NM strains are listed here as not typeable (NT). 

All EHEC strains are isolates from patients with diarrhea and/or HUS except for strain 86-24eaeΔ10, which is a derivative of strain 86-24 with an eae in-frame deletion mutation constructed in our laboratory (46), and strain EDL933, which was isolated from contaminated meat associated with an outbreak (55, 66). All strains carry the eae gene except the deletion mutant 86-24eaeΔ10 (3, 30, 46, 62a; 70). CDC, Centers for Disease Control and Prevention. 

Strain 97-3256 was determined to carry the stx2 gene by PCR analysis (62a). Although most O55:H7 strains isolated thus far are EPEC, there is documentation of another O55:H7 stx2⁺ strain (67).