Acute diarrhea

This page is for adult patients. For pediatric patients, see:

diarrhea (peds)

Background

Gasterointestinal anatomy.

Layers of the Alimentary Canal. The wall of the alimentary canal has four basic tissue layers: the mucosa, submucosa, muscularis, and serosa.

• 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
    • Foreign travel associated with 80% probability of bacterial diarrhea (see Traveler's Diarrhea)

Definitions

• Diarrhea: Increased frequency of defection, usually >3 bowel movements per day
• Hyperacute: 1-6 hr
• Acute: less than 3 weeks in duration
• Gastroenteritis: Diarrhea with nausea and/or vomiting
• Dysentery: Diarrhea with blood/mucus/pus
• Invasive = Infectious

Clinical Features

Bristol Stool Chart.

History

• Possible food poisoning?
  • Symptoms occur within 6hr
• Does it resolve (osmotic) or persist (secretory) with fasting?
• Are the stools of smaller volume (large intestine) or larger volume (small intestine)
• Fever or abdominal pain? (diverticulitis, gastroenteritis, IBD)
• Bloody or melenic?
• Tenesmus? (shigella)
• Malodorous? (giardia)
• Recent travel? (Traveler's Diarrhea)
• Recent antibiotics? (C. diff)
• HIV/immunocompromised/high risk behaviors?
• Heat intolerance and anxiety? (thyrotoxicosis)
• Paresthesias or reverse temperature sensation? (Ciguatera)

Physical Exam

• Thyroid masses
• Oral ulcers, erythema nodosum, episcleritis, anal fissure (IBD)
• Reactive arthritis (Arthritis, conjunctivitis, urethritis)
  • Suggests infection with salmonella, shigella, campylobacter, or yersinia
• Rectal exam for fecal impaction
• Guaiac
• Abdominal pain out of proportion to exam (mesenteric ischemia)

Differential Diagnosis

Acute diarrhea

Infectious

• Viral (e.g. rotavirus)
• Bacterial
  • Campylobacter
  • Shigella
  • Salmonella (non-typhi)
  • Escherichia coli
    • E. coli 0157:H7
  • Yersinia enterocolitica
  • Vibrio cholerae
  • Clostridium difficile
• Parasitic
  • Giardia lamblia
  • Cryptosporidium
  • Entamoeba histolytica
  • Cyclospora
  • Microsporidium
• Toxin
  • Staphylococcus aureus
  • Bacillus cereus

Noninfectious

• GI Bleed
• Appendicitis
• Mesenteric Ischemia
• Diverticulitis
• Adrenal Crisis
• Thyroid Storm
• Toxicologic exposures
• Antibiotic or drug-associated
• Inflammatory bowel disease
  • Crohn's disease
  • Ulcerative colitis

Watery Diarrhea

• Enterotoxigenic E. coli (most common cause of watery diarrhea)
• Norovirus (often has prominent vomiting)
• Campylobacter
• Non-typhoidal Salmonella
• Enteroaggregative E. coli (EAEC)
• Enterotoxigenic Bacteroides fragilis

Traveler's Diarrhea

• Giardia lamblia
• Cryptosporidiosis
• Entamoeba histolytica
• Cyclospora
• Clostridium perfringens
• Listeriosis
• Helminth infections
• Marine toxins
  • Ciguatera
  • Scombroid poisoning
  • Paralytic shellfish poisoning
  • Neurotoxic shellfish poisoning
  • Diarrheal shellfish poisoning

Evaluation

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, nausea and vomiting
Physical findings	Nontoxic	Toxic
Abdominal Tenderness	No	Yes
Stool Blood, WBCs	No	Yes

Indications for Workup

Indicated for:

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

Stool Studies

Fecal leukocytes

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

Stool culture

• Plays minor role in ED evaluation
• Yield is only 1.5-5.5%
• Consider in patients with
  • Immunosuppression
  • Severe, inflammatory diarrhea (including bloody diarrhea)
  • Underlying IBD (need to distinguish between flare and superimposed infection)

O&P

• Indicated if parasitic cause is suspected:
  • Diarrhea >7d
  • Untreated water
  • AIDS
  • Bloody diarrhea with few or no fecal leukocytes (intestinal amebiasis)

C. diff toxin

• 10% false negative rate
• Turnaround time for results varies by institution

Chemistry

• Warranted in severely dehydrated patients

CXR

• Consider if diarrhea + cough (Legionella)

Imaging

• Consider abdominal CT if abdominal tenderness or suspicion of surgical abdomen (e.g. appendicitis, small bowel obstruction, mesenteric ischemia)
• Abdominal X-ray is almost never indicated given low sensitivity for pathology (e.g. obstruction)

Supportive Therapies

Oral rehydration therapy

• Fluids should contain sugar, salt, and water

Probiotics

• Lactobacilli and bifidobacterium
• 25% decrease in average duration of diarrhea (good evidence)

Diet Modification

• Eat: BRAT(Bananas, Rice, Applesauce and Toast) diet (no evidence)
• Avoid: Caffeine (increased gastric motility), raw fruit (increased 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

Loperamide

• 2mg PO per dose
  • Start: 4mg PO x1, then 2mg PO after each loose stool; Max: 16mg/day
• Contraindicated if suspect C. diff

Diphenoxylate/atropine

• Dose: 4mg QID x2d
• 2nd line agent (may cause cholinergic side effects)
• Contraindicated in pseudomembranous colitis, obstructive jaundice, and children <6y

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)
• The majority of patients, even with bacterial positive cultures, will recover from diarrhea illness without antibiotic therapy

Relative Indications for Antibiotics

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

Empiric Therapy

• Ciprofloxacin 500mg PO BID x 5 days OR
• Levofloxacin 599mg PO once daily x 5 days OR
• TMP/SMX 1 DS tablet PO BID x 5 days

Traveler's Diarrhea

• Therapy should be based on the geography of travel

Adult Options:

• Ciprofloxacin 750mg PO once daily x 1-3 days
  • First choice for use except in South and Southeast Asia
• Azithromycin 500mg PO q24h x 3 days OR 1000mg PO x 1
  • Nausea is a frequent adverse event
  • First choice for use in South and Southeast Asia
• Rifaximin 200mg PO TID x 3 days
  • Ineffective against mucosally invasive pathogens (Shigella, Salmonella, Campylobacter)
  • Considered very safe as it is not absorbed

Pediatric Options:

Avoid fluroquinolones

• Azithromycin 10mg/kg/day once daily x 3 days OR
• Ceftriaxone 50mg/kg/day once daily x 3 days

Culture Specific Antibiotics

Agent	Treatment
Clostridium difficile	Vancomycin 125 mg PO four times daily for 10 days Fidaxomicin 200 mg PO two times daily for 10 days
Campylobacter jejuni	Erythromycin 500mg PO BID x 5 days Ciprofloxacin 500mg PO BID x 5 days OR Azithromycin 500mg PO once daily x 5 days
Entamoeba histolytica	Metronidazole 750mg PO three times daily for 5-10 days PLUS Paromomycin 500mg q8hrs for 7 days OR Iodoquinol 650mg q 8hrs daily 20 days
Giardia lamblia	Metronidazole 250mg PO q8hrs for 7-10days Tinidazole 2g PO once
Microsporidium	Albendazole 400mg PO BID x 21 days + HAART therapy if HIV positive
Cryptosporidium	Paromomycin 500mg PO q8hrs x 14-28days +HAART therapy if HIV positive
Salmonella (non typhoid)	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 TMP/SMX 1 DS tab PO BID x 5 days Ceftriaxone 2g IV once daily x 5 days Levofloxacin 500mg PO once daily x 5 days Ciprofloxacin 500mg PO BID x 5 days
Shigella	Treatment extended for 10 days if immunocompromised' Ciprofloxacin 500mg PO BID x 5 days TMP/SMX 1 DS tab PO BID x 5 days Levofloxacin 500mg PO once daily x 5 days Azithromycin 500mg PO daily x 5 days
Vibrio Cholerae	Doxycycline 300mg PO as single dose TMP/SMX 1 tablet (5mg/kg) PO BID daily x 3 daily Azithromycin 20mg/kg (1g) PO once
Yersinia enterocolitica	Antibiotics are not required unless patient is immunocompromised or systemically ill Ciprofloxacin 500mg PO BID daily Levofloxacin 500mg PO once daily TMP/SMX 1 DS tab (5mg/kg) PO BID

Disposition

• Hospitalization should be individualized based on the patient's ability to tolerate oral hydration, have adequate social support, and also based on complicating comorbidities.
• Majority of patients can be treated as an outpatient
• Observation or admission is required for those with severe disease, and significant dehydration with other end organ complications

See Also

• Diarrhea (Peds)
• Traveler's Diarrhea
• Clostridium Difficile