Can E coli (Escherichia coli) cause bloody diarrhea?

E. coli and Bloody Diarrhea

Yes, Escherichia coli (E. coli), particularly Shiga toxin-producing E. coli (STEC) strains, are a significant cause of bloody diarrhea. 1, 2

Types of E. coli Associated with Bloody Diarrhea

• STEC (Shiga toxin-producing E. coli): Defined by the presence of Shiga toxin genes (stx1 and/or stx2) 2

  • E. coli O157:H7 is the predominant serotype in North America 2, 3
  • Non-O157 STEC serotypes (including O26, O45, O103, O111, O121, and O145) can also cause bloody diarrhea 2, 4

• Enterohemorrhagic E. coli (EHEC): A subset of STEC that causes bloody diarrhea and can lead to hemolytic uremic syndrome (HUS) 3

Clinical Presentation

STEC infections typically present with:

• Initial non-bloody diarrhea that progresses to bloody diarrhea within several days 5, 6
• Severe abdominal cramping 6
• Minimal or no fever (an important distinguishing feature) 1, 6
• Absence of fecal leukocytes in many cases 6

Diagnostic Considerations

• All stool specimens from patients with acute community-acquired diarrhea should be tested for STEC 1

• Testing should not be limited by:

  • Presence/absence of visible blood in stool (STEC can cause non-bloody diarrhea too) 1
  • Patient age (though children are at higher risk) 1
  • Season (though more common in summer) 1

• Stool should be tested as early as possible in the illness course 1

• Both O157 STEC and non-O157 STEC testing should be performed 2

Complications

• Hemolytic uremic syndrome (HUS) - particularly in children and elderly patients 5, 3, 6
• Thrombotic thrombocytopenic purpura (TTP) 6

Differential Diagnosis for Bloody Diarrhea

According to the IDSA guidelines, other pathogens that can cause bloody diarrhea include: 1

• Shigella
• Salmonella
• Campylobacter
• Entamoeba histolytica
• Noncholera Vibrio species
• Yersinia
• Balantidium coli
• Plesiomonas

Treatment

• Supportive care is the mainstay of treatment 5
• Avoid antibiotics in suspected STEC O157:H7 infections as they may increase the risk of HUS 2
• Monitor for signs of HUS (thrombocytopenia, hemolytic anemia, renal failure) 2
• Early volume expansion may help reduce renal damage in those at risk for HUS 2

Prevention

• Cook ground meats thoroughly
• Consume only pasteurized dairy products and juices
• Wash fruits and vegetables properly
• Practice good hand hygiene
• Prevent cross-contamination during food preparation 2

Key Clinical Pearls

1. The hallmark of STEC infection is the progression from non-bloody to bloody diarrhea over several days 5

2. STEC infections often present with minimal or no fever, which can help distinguish them from other causes of bloody diarrhea 1

3. Testing for E. coli O157:H7 requires specific culture techniques; many laboratories need to be specifically requested to test for STEC 6

4. The infectious dose for E. coli O157:H7 is very low (<100 organisms), making it highly transmissible 2