Bacterium
Shiga toxin-producing E. coli (STEC/EHEC)
Shiga-toxin pathotype linked to HUS
SHEE-guh TOK-sin
High-yield clue
Bloody diarrhea that can progress to hemolytic uremic syndrome (anemia, thrombocytopenia, kidney injury) is the defining pathotype clue.
Overview
A diarrheagenic pathotype of Escherichia coli that carries phage-encoded Shiga toxin genes, with O157:H7 the best-known serotype. It causes hemorrhagic colitis and is the leading infectious trigger of hemolytic uremic syndrome (HUS) in children.
Classification
- Gram-negative
- Diarrheagenic E. coli pathotype
- Shiga toxin (Stx1/Stx2) producing
- Enterobacterales
Lab & identification clues
- O157 does not ferment sorbitol on sorbitol-MacConkey (SMAC) vocabulary
- Shiga toxin immunoassay/PCR detection concept
- Toxin inactivates the 60S ribosomal subunit (protein-synthesis block)
- Non-O157 serotypes missed by sorbitol screening
Associations
- Undercooked ground beef and produce transmission
- Very low infectious dose epidemiology
- Hemolytic uremic syndrome (HUS) study association
- Cattle reservoir and outbreak framing
Commonly confused with
- Enterotoxigenic E. coli (ETEC)
- Shigella dysenteriae (also makes Shiga toxin)
Frequently asked questions
What is Shiga toxin-producing E. coli (STEC/EHEC)?
A diarrheagenic pathotype of Escherichia coli that carries phage-encoded Shiga toxin genes, with O157:H7 the best-known serotype. It causes hemorrhagic colitis and is the leading infectious trigger of hemolytic uremic syndrome (HUS) in children.
What is the Gram stain of Shiga toxin-producing E. coli (STEC/EHEC)?
Shiga toxin-producing E. coli (STEC/EHEC) is Gram negative.
What are the lab clues for Shiga toxin-producing E. coli (STEC/EHEC)?
Lab clues for Shiga toxin-producing E. coli (STEC/EHEC) include O157 does not ferment sorbitol on sorbitol-MacConkey (SMAC) vocabulary, Shiga toxin immunoassay/PCR detection concept, Toxin inactivates the 60S ribosomal subunit (protein-synthesis block), and Non-O157 serotypes missed by sorbitol screening.
What is Shiga toxin-producing E. coli (STEC/EHEC) commonly confused with?
Shiga toxin-producing E. coli (STEC/EHEC) is commonly confused with Enterotoxigenic E. coli (ETEC) and Shigella dysenteriae (also makes Shiga toxin).
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.