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Synonyms: Shiga toxin-producing E. coli, E. coli O157

Shiga toxin-producing E. coli (STEC), also known as enterohemorrhagic E. coli (EHEC), is the etiologc agent of sporadic and epidemic diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Amongst hundreds of infectious serotypes, O157:H7 has emerged as the most common STEC. Six non-O157 serogroups (O26, O45, O103, O111, O121, O145) account for the majority of non-O157 STEC outbreaks and can be equally pathogenic. Laboratory isolation of STEC is based on active screening of diarrheal stool on O157:H7 selective agar and confirmation with biochemical and serotypic tests. Because this method would miss non-O157 STEC, CDC recommends that other methods are used to detect Shiga toxin directly in fecal specimen or after overnight amplification in broth culture. Stanford Clinical Microbiology laboratory offers a multiplex, real-time PCR assay to detect all STEC serotypes by targeting Shiga toxin (stx1 and stx2) gene sequences after overnight enrichment in broth culture.