USMLE

Escherichia coli: Overview

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Bacteria - Gram Negative
  1. Neisseria spp: Overview
  2. Neisseria gonorrhoeae
  3. Neisseria meningitidis
  4. Haemophilus influenzae
  5. Bordetella pertussis
  6. Brucella
  7. Legionella pneumophila
  8. Pseudomonas aeruginosa: Overview
  9. Pseudomonas aeruginosa: Disease
  10. Salmonella Overview
  11. Salmonella typhi
  12. Salmonella enteritidis
  13. Shigella
  14. Yersinia enterocolitica
  15. Escherichia coli: Overview
  16. Enterohemorrhagic E. Coli (EHEC)
  17. Enterotoxigenic E. Coli (ETEC)
  18. Klebsiella pneumoniae
  19. Campylobacter jejuni
  20. Vibrio spp.
  21. Helicobacter pylori
  22. Borrelia burgdorferi (Lyme Disease)
  23. Leptospira interrogans
  24. Treponema pallidum: Overview
  25. Treponema pallidum: Diagnosis
  26. Congenital syphilis
  27. Chlamydia: Overview
  28. Chlamydia trachomatis
  29. Chlamydia pneumoniae vs. psittaci
  30. Rickettsia rickettsii
  31. Rickettsia typhi vs. prowazekii
  32. Anaplasma vs. Ehrlichia
  33. Coxiella burnetii (Q fever)

Escherichia coli Overview 

  • Characteristics
    • Gram negative rod
      • motile
    • Indole +
    • Lactose-fermenting
      • Grows on eosin methylene blue (EMB) agar, where lactose fermentation produces a blue-green color
      • Can also ferment glucose
    • Facultative anaerobic
  • Presentation
    • Over 100 strains cause disease
      • Each strain has different virulence factors, which determines disease
    • UTI
      • most common cause of UTI (>80%)
      • Mediated by pili/fimbriae
        • enable adhesion to uroepithelial surface
      • May present as cystitis, urethritis, or pyelonephritis
    • Diarrhea
      • ETEC causes watery diarrhea
      • EHEC causes bloody diarrhea
        • enteroinvasive E. coli (EIEC) strains are rare cause
    • Neonatal Meningitis
      • Mediated by K1 capsule
      • Prevents phagocytosis or complement activation
    • Sepsis
      • Most common cause of gram-negative sepsis
      • Mediated by LPS endotoxin
        • seen in all gram-negative bacteria
    • May be causative agent in a variety of other infections
      • osteomyelitis in sickle cell patients
      • intra-abdominal and lung abscesses
      • orchitis in older men
  • Treatment
    • Generally supportive, as antibiotics are rarely indicated