• Clinical science

Diarrheagenic E. coli


Escherichia coli (E. coli) is a gram-negative, rod-shaped flagellated bacterium. Although it is an essential component of the bacterial gut flora, disease may be caused by direct intake of a pathogenic E. coli subtype (e.g., in contaminated food) or spreading of the intestinal bacteria to another organ (cystitis, pneumonia). Enterohemorrhagic E. coli (EHEC), for instance, can lead to severe colitis and hemolytic-uremic syndrome (HUS), particularly in children and infants. In such cases, diarrhea should only be treated symptomatically, as antibiotics can lead to increased toxin secretions that exacerbate the course of disease. Supportive therapy without antibiotic therapy is also recommended for infection involving other strains of E. coli (ETEC, EPEC, and EIEC), but antibiotics may be indicated in certain cases.

General information

Do not treat with antibiotics if EHEC is suspected!


Enterohemorrhagic Escherichia coli (EHEC)

  • Pathogen: enterohemorrhagic Escherichia coli (EHEC) bacterium
    • Produces verotoxin/Shiga-like toxin that causes bloody diarrhea and possibly HUS
    • Various serotypes
      • O157:H7: strain that is most commonly associated with HUS worldwide
  • Transmission
    • Contaminated food (associated with industrial food production in developed countries)
      • Raw beef and milk
      • Raw vegetables
    • Fecal-oral: through contact with contaminated stool
    • At-risk groups: infants/toddlers and the elderly
  • Pathophysiology
  • Incubation period: 2–10 days
  • Clinical features
  • Diagnosis
  • Obligation to report: EHEC infection and HUS infection are reportable in most US states.
  • Treatment
    • See general guidelines for treating E. coli infection.
    • Monitor for possible development of HUS.
    • Avoid antiperistaltic agents (e.g., diphenoxylate/atropine) since they increase the risk of systemic complications.
    • No antibiotic therapy!
    • See HUS for its specific treatment.
  • Complications: hemolytic-uremic syndrome (particularly in infants/toddlers )

EHEC → "H" as in "Hemolytic-uremic syndrome" is an important complication!


Enterotoxigenic Escherichia coli (ETEC)

ETEC → "T" as in “Traveler's diarrhea


Enteropathogenic Escherichia coli (EPEC)

EPEC → "P" as in "Pediatrics" → infantile diarrhea


Enteroinvasive Escherichia coli (EIEC)