II. Causes: Bacteria

  1. Toxigenic (Enterotoxin binds Small Bowel: secretory, account for 80% of Bacterial Diarrhea)
    1. Enterotoxigenic E. coli (Traveler's Diarrhea)
      1. Most common Diarrhea in the returning traveler
    2. Vibrio Cholera
      1. Contaminated water ingestion is the classic, historical example (shellfish ingestion can also occur)
      2. Associated with rice-water stools, severe Dehydration, Hypokalemia
    3. Aeromonas
      1. Ingestion of well or spring water (esp. in young children or Immunocompromised patients)
    4. Staphylococcus aureus
      1. Most common Food Poisoning, rapid onset within hours (esp. eggs, mayonnaise)
    5. Bacillus cereus
      1. Rapid onset Food Poisoning within hours of ingestion (esp. fried rice)
    6. Clostridium perfringens
      1. Most common cause of acute Food Poisoning in U.S (esp. meat, poultry, gravy)
      2. Onset within 6 to 12 hours of ingestion (allows for in vivo toxin production) and self-resolves by 24 hours
      3. Associated with fever and Headache
    7. Scombroid Fish Poisoning
      1. Food Poisoning associated with Histamine release (esp dark fish such as mahi-mahi, tuna, mackeral)
    8. Ciguatera Poisoning
      1. Food Poisoning from ingested Neurotoxin with Anticholinergic effects (esp. large reef fish)
    9. Listeria monocytogenes
      1. Febrile, Food Poisoning from raw milk, soft cheeses and old meats (other soucrces include poultry and fish)
      2. High risk in pregnancy (with a 12 fold increased risk in pregnancy)
  2. Invasive or Inflammatory (Colonize, Adhere, and Invade: Dysentery, account or 20% of Bacterial Diarrhea)
    1. Nontyphoidal Salmonella
      1. Food Poisoning (esp. eggs, chicken) or pets (turtles, iguanas, frogs)
    2. Yersinia enterocolitica
      1. Mimics Appendicitis presentation with RLQ Abdominal Pain
      2. Associated with farm animal exposure
      3. Complications include Polyarthritis, Erythema Nodosum
    3. Shigella
      1. Associated with high fever (esp. children)
      2. Complications include Reiter's Syndrome, Hemolytic Uremic Syndrome
    4. Vibrio parahaemolyticus (or Vibrio haemolyticus)
      1. Food Poisoning (esp. shellfish or raw seafood)
    5. Campylobacter jejuni
      1. Most common Bacterial Diarrheal cause in the United States
      2. Food Poisoning (esp. poultry)
      3. May present as acute abomen
      4. Complications include Reiter's Syndrome, Hemolytic Uremic Syndrome, Guillain-Barre Syndrome
    6. Shiga-toxin producing E. coli (e.g. E. coli 0157:H7, Enterohemorrhagic E. coli)
      1. Food Poisoning (esp. ground beef, seed sprouts or unpasteurized milk)
      2. Complications
        1. Hemolytic Uremic Syndrome (children)
        2. Thrombotic Thrombocytopenic Purpura (elderly)
    7. Clostridium difficile
      1. Antibiotic-Associated Diarrhea
    8. Other uncommon causes
      1. Klebsiella oxytoca (uncommon)
        1. Like Clostridium difficile, causes Antibiotic-Associated Diarrhea, that may be hemorrhagic
        2. Improves after stopping antibiotics and NSAIDs
      2. Intestinal Spirochetosis (Brachyspira pilosicoli, Brachyspira aalborgi)
        1. Anaerobic Spirochetes colonize colon and may cause colitis (Abdominal Pain, Rectal Bleeding)
        2. May respond to Penicillin, Metronidazole, Ceftriaxone and Moxifloxacin
          1. Brooke (2003) Antimicrob Agents Chemother 47(7):2354-7 +PMID:12821498 [PubMed]

IV. Causes: Virus (Malabsorption)

  1. Norovirus (90% of non-Bacterial Diarrhea)
  2. Rotavirus
  3. Adenovirus
  4. Norwalk Virus
  5. Astrovirus
  6. Calicivirus

V. Causes: Parasites (Chronic Diarrhea or Acute Dysentery)

VI. Differential Diagnosis

  1. See Diarrhea

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