Difference between revisions of "Acute diarrhea"

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*Dose: 4mg QID x2d
*Dose: 4mg QID x2d
*2nd line agent (may cause cholinergic side effects
*2nd line agent (may cause cholinergic side effects
===[[Antibiotics]] for Infectious Diarrhea===
===[[Antibiotics]] for Infectious Diarrhea===

Revision as of 15:27, 15 April 2015


  • Almost all true diarrheal emergencies are of noninfectious origin
  • 85% of diarrhea is infectious in etiology
    • Viruses cause vast majority of infectious diarrhea
    • Bacterial causes are responsible for most cases of severe diarrhea
  • Definitions
    • Diarrhea: Increased frequency of defection, usually >3 bowel movements per day
    • Hyperacute: 1-6 hr
    • Acute: less than 3 wks in duration
    • Gastroenteritis: Diarrhea with nausea and/or vomiting
    • Dysentery: Diarrhea with blood/mucus/pus
    • Invasive = Infectious



  1. Possible food poisoning?
    1. Symptoms occur within 6hr
  2. Does it resolve (osmotic) or persist (secretory) w/ fasting?
  3. Are the stools of smaller volume (large intestine) or larger volume (small intestine)
  4. Fever or abdominal pain? (diverticulitis, gastroenteritis, IBD)
  5. Bloody or melenic?
  6. Tenesmus? (shigella)
  7. Malodorous? (giardia)
  8. Recent travel? (Traveler's Diarrhea)
  9. Recent Abx? (C. diff)
  10. HIV/immunocomp/sexual hx
  11. Heat intolerance and anxiety? (thyrotoxicosis)
  12. Paresthesias or reverse temperature sensation? (Ciguatera)

Physical Exam

  1. Thyroid masses
  2. Oral ulcers, erythema nodosum, episcleritis, anal fissure (IBD)
  3. Reactive arthritis (Arthritis, conjunctivitis, urethritis)
    1. Suggests infx w/ salmonella, shigella, campylobacter, or yersinia
  4. Rectal exam for fecal impaction
  5. Guaiac
  6. Abdominal pain out of proportion to exam (mesenteric ischemia)

Toxigenic v. Infectious

Characteristic Toxic Infectious/Invasive
Incubation 2-12h 1-3d
Onset abrupt gradual
Duration <10-24h 1-7days
Fever No Yes
Abdominal Pain Minimal Yes, tenesmus
Systemic No Yes, myalgias, N/V
Physical findings Nontoxic Toxic
Abdominal Tenderness No Yes
Stool Blood, WBCs No Yes


Differential Diagnosis

Acute diarrhea



Watery Diarrhea

Traveler's Diarrhea


Indicated for:

  • Profuse watery diarrhea w/ signs of hypovolemia
  • Severe abdominal pain
  • Fever >38.5 (101.3) (suggests infection w/ invasive bacteria)
  • Symptoms >2-3d
  • Blood or pus in stool (E. coli 0157:H7)
  • Recent hospitalization or abx use
  • Elderly or immunocompromised
  • Systemic illness w/ diarrhea (esp if pregnant (listeria))

Stool Studies

Fecal leukocytes

  1. Used to differentiate invasive from noninvasive infectious diarrheas
  2. Sn 50-80%, Sp 83% for presence of bacterial pathogen
  3. If pt has +leukocytes but negative infection consider IBD

Stool culture

  1. Plays minor role in ED evaluation
  2. Yield is only 1.5-5.5%
  3. Consider in pts w/:
    1. Immunosuppression
    2. Severe, inflammatory diarrhea (including bloody diarrhea)
    3. Underlying IBD (need to distinguish between flare and superimposed infection)


  1. Indicated if parasitic cause is suspected:
    1. Diarrhea >7d
    2. Untreated water
    3. AIDS
    4. Bloody diarrhea w/ few or no fecal leukocytes (intestinal amebiasis)

C. diff toxin

  1. 10% false negative rate
  2. Takes 24hr to run


  1. Warranted in severely dehydrated pts

Abdominal X-ray

  1. Consider if h/o abdominal sx (r/o obstruction)

Chest Xray

  1. Consider if diarrhea + cough (Legionella)


  1. Consider if suspect mesenteric ischemia


Supportive Therapies

Oral rehydration

  1. Fluids should contain sugar, salt, and water


  1. Lactobacilli and bifidobacterium
  2. 25% decrease in average duration of diarrhea (good evidence)

Diet Modification

  1. Eat: BRAT(Bananas, Rice, Applesauce and Toast) diet (no evidence)
  2. Avoid: Caffeine (incr gastric motility), raw fruit (incr osmotic diarrhea), lactose

Bismuth subsalicylate

  • Consider when loperamide is contraindicated (high fever, dysentery)
  • Dose: 30 mL or 2tab q30 min for 8doses; repeat on day 2
  • Caution: may cause bismuth encephalopathy in HIV patients

Diphenoxylate and atropine

  • Dose: 4mg QID x2d
  • 2nd line agent (may cause cholinergic side effects

Antibiotics for Infectious Diarrhea

  • Most cases of diarrhea are not from infectious causes. If the patient suspects that there is blood in the stool but there is no abdominal pain, and no fever, the cause is unlikely to be from a bacterial cause. Also avoid antibiotics in E. Coli 0157:H7 (EHEC) cases due the risk of Hemolytic Uremic Syndrome (HUS)[2]
  • The majority of patients, even with bacterial positive cultures, will recover from diarrhea illness without antibiotic therapy[3]

Relative Indications for Antibiotics[4]

  1. Suspected bacterial diarrhea
  2. Bloody diarrhea (except for EHEC) with fever and systemic illness
  3. Occult blood or +fecal leukocytes
  4. Moderate to severe travelers' diarrhea (>4 stools/d, fever, blood, or mucus in stool)
  5. >8 stools/d
  6. Volume depletion
  7. >1wk duration
  8. Immunocompromised
  9. Toxic appearance

Empiric Therapy

Clostridium difficile

Campylobacter jejuni

Entamoeba Histolytica

Giardia lamblia




  • Treatment is not recommended routinely but should be considered if:
  • Immunocompromised
  • Age<6 mo or >50yo
  • Has any prostheses
  • Valvular heart disease
  • Severe Atherosclerosis
  • Active Malignancy
  • Uremic

Options: Immunocompromised patients should have 14 days of therapy


Treatment extended for 10 days if immunocompromised'

Vibrio Cholerae

Yersinia enterocolitica

Antibiotics are not required unless patient is immunocompromised or systemically ill


  • Conservatism should be the rule with the young and the elderly

See Also


  1. Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
  2. Aranda-Michel J et al. Acute diarrhea: A practical review. AmJMed. 1999;106:670-676.
  3. DuPont HL et al. Practice Parameters Committee of the American College of Gastroenterology. Guidelines on acute infectious diarrhea in adults. Am J Gastroenterol. 1997;92:1962-1975.
  4. IDSA Practice Guidelines for the Management of Infectious Diarrhea. 2001. fulltext