Escherichia coli O157:H7 (E Coli)

Compiled By: Julie A. Albrecht, Ph.D., Associate Professor

The Organism: The specific Escherichia coli serotype O157:H7 is an aerobic bacteria that produces a Shiga toxin. The bacteria grow slowly at refrigeration temperatures. E. coli O157:H7 has been shown to survive in acidic food products such as apple cider and mayonnaise.

PDF Fact Sheet

Sources of the organism:

  • Intestinal tracts of infected animals
  • Fecally contaminated water

Associated foods:

  • Ground beef
  • Unpasteurized milk
  • Unpasteurized apple cider
  • Lettuce

Microorganism Characteristics: Gram negative toxin forming aerobic bacteria

Growth conditions:

  • Temperature range: 4- 45°C (39-113°F); can survive refrigeration and freezing
  • Optimum Temperature: 37°C (98.6°F)
  • pH range: can survive at pH 3.6
  • Lowest reported Aw for growth: .90
  • Survives fermentation, drying and storage (3.5% NaCl & 69 ppm Sodium Nitrite)

The Disease: Hemorrhagic colitis is the name of the disease caused by E. coli O157:H7. The elderly and children are more susceptible to this disease. A possible complication is hemolytic uremic syndrome (HUS), a urinary tract infection that is a leading cause of acute kidney failure in children.

Symptoms include:

  • Severe abdominal cramps
  • Bloody diarrhea
  • Nausea
  • Vomiting
  • Low-grade fever

Onset time:

  • 2- 4 days

Infective Dose:

  • Small numbers (5- 10 cells) of viable E.coli O157:H7 cells need to be consumed for symptoms of the illness to develop.

Duration of symptoms:

  • 5-10 days


  • Thoroughly cook ground beef products (155°F for 15 seconds or 160°F).
  • Proper hand washing techniques when handling raw ground beef.
  • Reheat foods to 165°F for 15 seconds.
  • Proper sanitation of food contact surfaces and utensils
  • Refrigerate foods at 41°F or below.