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Enterohemorrhagic Escherichia coli infection
Other Resources UpToDate PubMed

Enterohemorrhagic Escherichia coli infection

Contributors: Bilal Naseer MD, William Bonnez MD, Ricardo M. La Hoz MD
Other Resources UpToDate PubMed


Enterohemorrhagic Escherichia coli (EHEC) are specific strains of E coli responsible for bloody diarrhea and a hemolytic uremic syndrome (HUS).

EHEC first came to attention in 1982, when the investigation of 2 outbreaks in Oregon and Michigan identified a new serotype, O157:H7. EHEC differs from other E coli strains by producing toxins that play an important role in pathogenesis and are similar to those of Shigella dysenteriae. Hence, EHEC are also known as Shiga toxin-producing E coli (STEC).

They account for 0.8%-3% of all cases of diarrhea in the United States and a higher percentage of bloody diarrheas (15%-36%).

The incubation period is 3-4 days. Most EHEC cases are due to ingestion of contaminated food or water. Cattle are the major reservoir. Human transmission occurs by ingestion of undercooked beef, raw milk, or other products contaminated by the intestinal contents of cattle. Contaminated vegetables (eg, romaine lettuce) have also been identified as sources of outbreaks. Occasional cases of contaminated water have also been reported. It is estimated that the infectious dose of E coli O157:H7 is only 10-100 organisms.

Mortality is 1%-2% overall.

HUS is the feared complication of EHEC infection, occurring in up to 20% of cases, typically within 5-14 days of EHEC infection onset. It is characterized by acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia. It is more common in children aged younger than 5 years.


A04.3 – Enterohemorrhagic Escherichia coli infection

111839008 – Intestinal infection caused by Escherichia coli

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Differential Diagnosis & Pitfalls

The primary differential diagnosis includes other causes of inflammatory diarrhea causing bloody stools such as:
  • Salmonellosis
  • Shigellosis
  • Campylobacter infections
  • Yersinia enterocolitica infection – Requires special media. Serologic diagnosis is also available.
  • Cutaneous amebiasis – Requires a microscopic examination of the stools. Serology is also available.
Note that EHEC serotypes other than O157:H7 have been described.

Noninfectious differential diagnosis:
  • Crohn disease
  • Ulcerative colitis
  • Acute radiation enteritis
  • Ischemic colitis

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Last Updated:10/23/2023
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Enterohemorrhagic Escherichia coli infection
A medical illustration showing key findings of Enterohemorrhagic Escherichia coli infection : Chills, Bloody diarrhea, Nausea, Vomiting, Abdominal cramp, Contaminated food exposure
Copyright © 2024 VisualDx®. All rights reserved.