Diarrhea, Adult

Description

Bowel movements characterized as frequent (>3/day), loose, and watery owing to an infectious or toxin exposure

Etiology

• Viruses:
  • 50–70% of all cases
• Invasive bacteria:
  • Campylobacter:
    • Contaminated food or water, wilderness water, birds, and animals
    • Most common bacterial diarrhea
    • Gross or occult blood is found in 60–90%.
  • Salmonella:
    • Contaminated water, eggs, poultry, or dairy products
    • Typhoid fever (Salmonella typhi) characterized by unremitting fever, abdominal pain, rose spots, splenomegaly, and bradycardia
  • Shigella:
    • Fecal or oral route
  • Vibrio parahaemolyticus:
    • Raw and undercooked seafood
  • Yersinia:
    • Contaminated food (pork), water, and milk
    • May present as mesenteric adenitis or mimic appendicitis
• Bacterial toxin:
  • Escherichia coli:
    • Major cause of traveler's diarrhea
    • Ingestion of food or water contaminated by feces
  • Staphylococcus aureus:
    • Most common toxin-related disease
    • Symptoms 1–6 hr after ingesting food
  • Bacillus cereus:
    • Classic source—fried rice left on steam tables
    • Symptoms within 1–36 hr
  • Clostridium difficile:
    • Antibiotic-associated enteritis linked to pseudomembranous colitis
    • Incubation period within 10 days of exposure or initiation of antibiotics
  • Aeromonas hydrophila:
    • Aquatic sources primarily
    • Affects children <3 yr of age
    • Fecal leukocytes absent
  • Cholera:
    • Caused by enterotoxin produced by Vibrio cholerae
    • Profuse watery stools with mucus (classic appearance of rice-water stools)
• Protozoa:
  • Giardia lamblia:
    • Most common cause of parasite gastroenteritis in North America
    • High-risk groups: Travelers, children in day care centers, institutionalized people, homosexual men, and campers who drink untreated mountain water
  • Cryptosporidium parvum:
    • Commonly carried in patients with AIDS
  • Entamoeba histolytica (entamebiasis):
    • 5–10% extraintestinal manifestations (hepatic amebic abscess)

• Most are viral in origin and self-limited.
• Rotavirus accounts for 50%.
• Shigella: Infections associated with seizures
• Focus evaluation on state of hydration.