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Acute DiarrheaAka: Diarrhea, Gastroenteritis

Definition of Diarrhea
1. Adults: >200 g/day of stool
2. Children: >20 g/kg/day of stool
3. Frequent liquid stools
Pathophysiology
1. Small intestine secretes and reabsorbs 10 liters/day
  1. Extrusion of Chloride from villus crypt cell (cAMP)
  2. Absorption at villus tip
2. Diarrhea classified as:
  1. Watery Diarrhea
    1. Secretory Diarrhea
      1. Stool Sodium high (60-120 meq/L)
    2. Osmotic Diarrhea (osmotic loss of free water)
      1. Stool Sodium low (30-40 meq/L)
      2. Results from damage to intestinal microvilli
  2. Inflammatory Diarrhea
    1. Stool with pus or blood present
  3. Fatty diarrhea (Malabsorption)
    1. Large greasy, frothy pale stools with foul odor
3. Serum Electrolyte loss
  1. Serum Bicarbonate loss
  2. Serum Potassium loss
Etiologies (General)
1. Infectious Diarrhea Causes
  1. Viruses (30-40% of episodes)
  2. Bacteria and Parasites (20-30% of episodes)
    1. Campylobacter jejuni (most common bacteria)
    2. Salmonella
    3. Shigella
    4. E. coli 0157:H7 (30% of infectious bloody stool)
  3. Other Infectious Disease
2. Noninfectious Causes
  1. See Osmotic Diarrhea
  2. See Secretory Diarrhea
  3. Common Causes
    1. Intestinal Obstruction
    2. Toxic Ingestions
    3. Inflammatory and Allergic Conditions
Risk Factors
1. Recent travel to endemic area
  1. See Traveler's Diarrhea
2. Foodborne Illness
3. Waterborne Illness
4. Day care exposure
5. High-risk sexual behavior
  1. See Diarrhea from Sexually Transmitted Disease
6. Antibiotic use within 6 months (Clostridium difficile)
7. Immunosuppression
Evaluation Protocol
1. See Labs and Endoscopy below
2. Community-acquired, Traveler's Diarrhea or Dysentery
  1. Stool Cultures
    1. Salmonella
    2. Shigella
    3. Campylobacter
    4. Escherichia coli 0157:H7 (STEC: Shiga Toxin E coli)
      1. Shiga Toxin (if bloody stool)
      2. Avoid antimicrobial agents
  2. Clostridium difficile Toxins
    1. Indicated for recent antibiotics or Chemotherapy
  3. Consider antibiotic coverage (if not STEC)
    1. Quinolone if suspected Shigellosis
    2. Macrolide for suspected Campylobacter
3. Nosocomial Diarrhea (after 3 days of hospitalization)
  1. Clostridium difficile Toxins
  2. Consider community acquired labs as above
  3. Discontinue antibiotics if possible
  4. Consider Flagyl if worsens or persists
4. Persistent Diarrhea >7 days (esp. immunocompromised)
  1. Fecal Leukocytes or Fecal Lactoferrin
  2. Parasitic Infection evaluation
    1. Giardia
    2. Cryptosporidium
    3. Cyclospora
    4. Isospora belli
  3. Opportunistic infection in HIV positive patients
    1. Community acquired labs as above
    2. Microsporidia
    3. Mycobacterium Avium Intracellulare Complex
Labs
1. Multiple stool specimens (Increased yield)
  1. Fecal Leukocytes
  2. Consider Stool Culture
  3. Consider Stool Ova and Parasites (>7 days diarrhea)
2. Consider sending stool for antigen evaluation
  1. Giardia lamblia antigen
    1. Indicated for diarrhea >7 days and >10 stools/day
  2. Clostridium difficile Toxin
    1. Indicated if recent antibiotics or hospitalization
  3. Rotavirus antigen
    1. Indicated for defining local outbreak
3. Serum Electrolytes (e.g. Chem8)
Endoscopy
1. Does not distinguish Infectious from Inflammatory
2. Sexually Transmitted Disease (STD)
  1. Lesions in Distal 15 cm in homosexual men
  2. Herpes Virus
  3. Neisseria Gonorrhea
    1. Nonspecific findings limited to rectum
    2. Biopsy and Culture show superficial exudates
  4. Syphilis
    1. Rectal Papules, chancres, and ulcers
  5. Chlamydia (Lymphogranuloma venereum)
    1. Similar to Inflammatory Bowel Disease
References
1. Guerrant (2001) Clin Infect Dis 32:331

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This page was written by Scott Moses, MD. This page was last revised on 4/26/2008 9:13:09 PM. This page was last published on 4/29/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.