E. coli Infections: Symptoms, Risks & Complications

Escherichia coli pathotypes cause a spectrum of illness. Shiga toxin-producing E. coli (STEC, e.g., O157:H7) is the most notorious for severe complications.

Common Symptoms (STEC)

• Diarrhea (often bloody) – hallmark.
• Severe abdominal cramps.
• Nausea, vomiting.
• Low-grade fever (or none).
• Fatigue, malaise.

Onset: 1–10 days post-exposure (median 3–4 days). Duration: 5–10 days.

Serious Complications

• Hemolytic Uremic Syndrome (HUS): Triad of microangiopathic hemolytic anemia, thrombocytopenia, acute kidney injury. Occurs in 5–15% of STEC (mostly children <5, elderly). Can cause CKD, neurologic injury, death.
• Extraintestinal infections: UTI (uropathogenic E. coli – UPEC), bacteremia/sepsis, neonatal meningitis (K1 capsule), pneumonia, wound infections.

Other Pathotypes

• ETEC (travelers’ diarrhea) – heat-labile/stable toxins.
• EPEC (infant diarrhea).
• EAEC (persistent diarrhea, HIV).
• EIEC (dysentery-like, Shigella-like).
• AIEC (associated with Crohn’s).

Diagnosis & Treatment

• Stool culture + PCR panel (detects STEC, other pathogens).
• Do NOT use antibiotics for STEC – may increase HUS risk (induces phage → more toxin). Supportive: hydration, electrolyte replacement.
• Antibiotics indicated for extraintestinal E. coli (UTI, sepsis) – guided by susceptibility.

Prevention

• Cook ground beef to 160°F (71°C).
• Pasteurized milk/juice; wash produce.
• Hand hygiene after animals, diapers, bathroom.
• Avoid swallowing recreational water.

Bloody diarrhea + abdominal cramps → seek care; avoid antidiarrheals/antibiotics until STEC ruled out.