HYBRIDIZATION OF STRAINS OF ESCHERICHIA-COLI O157 WITH PROBES DERIVEDFROM THE EAEA GENE OF ENTEROPATHOGENIC ESCHERICHIA-COLI AND THE EAEA HOMOLOG FROM A VERO CYTOTOXIN-PRODUCING STRAIN OF ESCHERICHIA-COLI O157

A total of 375 Escherichia coli 0157 strains were tested by colony hyb ridization with the eae probe from the central portion of the eaeA gen e of the classical enteropathogenic E. coli strain E2348/69. They were also tested with a probe, eaeO157, from the C-terminal end of the eae gene homolog from a Vero cytotoxin (VT)-producing strain of E. coli ( VTEC) of serotype Ot57:H7. Both probes hybridized with all 246 0157:H7 or H- VTEC strains tested. The majority were from human infections, a nd the remainder were from cattle. A further 10 strains (H7 or H-) hyb ridized with both eae and eaeO157 sequences but not with VT probes. Th ey resembled 0157 VTEC and were probably naturally occurring derivativ es that had lost VT genes. The remaining 119 strains of 0 157 were fro m human, animal, and food sources and belonged to 16 H types other tha n H7 or were H-. They were VT negative and differed in their propertie s from 0157 VTEC: generally they fermented sorbitol in 1 day, produced beta-glucuronidase, and could not be phage typed by the scheme for 01 57 VTEC. The eae probe but not the eaeO157 sequence hybridized with 18 H8 or H39 strains, predominantly from human diarrhea. The remaining 1 01 VT-negative strains hybridized with neither probe. However, 16 stra ins of 0157:H45 hybridized with a probe for diffusely adherent E. coli and attached to HEp-2 cells in a diffuse pattern. Serogroup 0157 comp rises strains with heterogeneous properties. The eaeO157 probe is a va luable addition to the VT probes used to differentiate 0157 strains.