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Escherichia coli

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Escherichia coli, E. coli, Enterotoxigenic E. coli, ETEC, Enteroinvasive E. coli, EIEC, Enteroadherent E. coli, EAEC

  • Epidemiology
  1. Foodborne Illness
    1. See Traveler's Diarrhea
    2. See Enterohemorrhagic E. coli (EHEC)
  2. Waterborne Illness
    1. Outbreak at Rockford, IL lake swimming area (n=12)
    2. References
      1. MMWR (1996) 45:437-9 [PubMed]
  • Pathophysiology
  1. Escherichia coli is a human colonizer, normal colonic flora
    1. Strains become pathogenic when they acquire DNA from other organisms (see Bacteria for mechanisms)
  2. Virulence factors (dependent on strain)
    1. Intestinal epithelial cell invasion
    2. Mucosal adherence via Pili (colonization factor)
      1. E. coli 0157:H7 and various other serotypes (over 200)
    3. Iron-binding siderophore
      1. E. coli can harvest iron from human Transferrin or lactoferrin
    4. Exotoxins
      1. Heat labile toxin (LT, similar to Cholera toxin)
      2. Heat stable toxin (ST)
      3. Shiga-like toxin (e.g. 0157:H7)
        1. See Enterohemorrhagic E. coli (EHEC)
    5. Endotoxins
      1. Lipid A
        1. Lipopolysaccharide (LPS) layer subcomponent
  3. Conditions caused by E. coli
    1. Acute Diarrhea (see types below)
    2. Neonatal Meningitis (first month of life)
    3. Nosocomial Pneumonia
    4. Gram NegativeSepsis (esp. hospitalized patients)
    5. Urinary Tract Infections (Acute Cystitis, Pyelonephritis)
      1. Increased virulence with mucosal adherence via Pili (colonization factor)
  • Types
  1. Enterotoxigenic E. coli (ETEC)
    1. Most common pathogen in Traveler's Diarrhea (Cholera-like rice water Diarrhea)
    2. Mucosal adherence to intestinal epithelial cells via Pili (colonization factor)
    3. Releases exotoxins, heat labile (LT) and heat stable (ST)
      1. Exotoxins inhibit intestinal Sodium and chloride reabsorption
      2. Exotoxins promote chloride and bicarbonate excretion from intestinal mucosa
      3. Results in osmotic water losses, which can be severe (liters of fluid losses/day)
  2. Enteroinvasive E. coli (EIEC)
    1. Causes acute Dysentery-like Diarrhea
    2. Similar to Shigella (encoded by the same Plasmid), allowing for intestinal epithelial cell invasion
    3. Also releases Shiga-Toxin in smaller amounts
    4. Immune-mediated response with fever and bloody Diarrhea
  3. Enteroadherent E. coli (EAEC)
    1. Causes Diarrhea in infants
  4. Enterohemorrhagic E. coli (EHEC)
    1. See Enterohemorrhagic E. coli (EHEC)
    2. Causes bloody Diarrhea and abdominal cramping
    3. Includes a subset of Shiga Toxin-producing E. coli (e.g. 0157:H7) with a risk of Hemolytic Uremic Syndrome
    4. Rapid onset in 12-72 hours
  • Management
  1. See Acute Diarrhea
  2. See Traveler's Diarrhea
  3. Supportive Care
    1. Oral Rehydration
    2. Avoid anti-motility (e.g. Imodium may worsen disease)
  4. Antibiotics
    1. Indications
      1. Severe cases
    2. Contraindications
      1. Enterohemorrhagic E. coli (EHEC, E. coli 0157:H7)
        1. Risk of Hemolytic Uremic Syndrome
    3. Disadvantages of Antibiotics
      1. Antibiotics do not alter disease course
      2. May increase Hemolytic Uremic Syndrome risk
    4. Course
      1. Enterotoxigenic E. coli: Treat for 3 days
      2. Enteroinvasive E. coli: Treat for 5 days
    5. Adults - first line
      1. Ciprofloxacin 500 mg twice daily for 3 days
    6. Adults - second line
      1. Trimethoprim-Sulfamethoxazole (Bactrim) 160/800 mg twice daily for 3 days
      2. Azithromycin 500 mg daily for 3 days (ETEC only)
    7. Children
      1. Trimethoprim-Sulfamethoxazole (Bactrim) 10 mg Trimethoprim/kg/day orally divided twice daily for 3 days
      2. Azithromycin (ETEC only)
  • Resources
  • References
  1. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, 74-5
  2. Bower (1999) Pediatr Infect Dis J 18:909-10 [PubMed]