Diarrhea

Snapshot

• A 25-year-old man presents to his primary care physician for evaluation of diarrhea. He had recently gone to Mexico for spring break, where he stayed in a hostel with his friends. He spent a lot of time on the beach, swimming in caves, and hiking. He reports having onset of watery diarrhea about a week ago. He has not had any fevers, nausea, or vomiting. He does recall eating multiple rounds of raw oysters while in Mexico. He is found to be dehydrated, with poor skin turgor and dry mucous membrane.

Introduction

• Overview
  • acute diarrhea is characterized by acute onset of >3 bowel movements/day lasting <14 days and is often caused by infection
  • persistent diarrhea lasts 2-4 weeks
  • chronic diarrhea lasts >4 weeks and is often caused by underlying conditions such as inflammatory bowel disease or fat malabsorption
• Epidemiology
  • incidence
    • very common
    • rotavirus is most common cause of infectious diarrhea worldwide
      • vaccine available
    • acute diarrhea is the second cause of childhood mortality in the world
  • demographics
    • viral diarrhea is most common in children
      • especially rotavirus and adenovirus
• Etiology
  • infections
    • viruses
    • bacteria
    • parasites
  • drug-induced
    • quinidine
    • colchicine
    • cytotoxic agents
    • chemotherapy
  • food allergies
  • toxic ingestions
  • autoimmun
  • small intestine bacterial overgrowth, often secondary to scleroderma or diabetes
• Pathogenesis
  • types of diarrhea
    • exudative/inflammatory diarrhea
      • frequent, small-volume, and bloody stools
      • indicates disrupted and inflamed mucosa
      • etiologies
        • infectious (i.e., Shigella, Salmonella, E. coli, Campylobacter, amebiasis)
        • idiopathic inflammatory bowel disease (ulcerative colitis, Crohn disease)
        • ischemic colitis
    • fatty diarrhea
      • weight loss and greasy or bulky stools that float that are often chronic
      • etiologies
        • fat malabsorption
    • watery diarrhea
      • osmotic diarrhea
        • due to osmotic pull of water into the intestinal lumen
        • etiologies
          • giardiasis
          • laxatives
          • lactose intolerance
      • secretory diarrhea
        • due to active secretion of water
        • etiologies
          • infectious (i.e., enterotoxic E. coli, Vibrio)
          • carcinoid syndrome
          • gastrinoma
          • drugs (i.e., colchicine)

Infectious Bloody vs Watery Diarrhea
Bloody Diarrhea	Watery Diarrhea
CampylobacterE. histolyticaEnterohemorrhagic E. coliEnteroinvasive E. coliNon-thypoidal SalmonellaShigellaY. enterocolitica	C. difficileC. perfringensEnterotoxigenic E. coliGiardiaCryptosporidiumV. choleraeRotavirusNorovirusAdenovirusS. aureus

High Yield Risk Factors
Exposure	Risk Factors	Associated Organisms
Daycare		Rotavirus, astrovirus, calicivirus, Campylobacter, Shigella, Giardia, Cryptosporidium
Food	Dairy	Campylobacter, Salmonella
Eggs	Salmonella
Beef	E. coli
Poultry	Campylobacter, Salmonella
Pork	C. perfringens, Y. enterocolitica
Seafood	Astrovirus, Vibrio
Oysters	Calicivirus, Vibrio
Rice/pasta	Bacillus cereus
Water exposure	Swimming pools	Shigella
Contaminated water with cysts	Giardia, E. histolytica, Cryptosporidium
Travel history	“Traveler’s” diarrhea	E. coli, Giardia, Salmonella, Shigella, Campylobacter
Camping/hiking	Giardia
Past medical history	Antibiotics/hospitalization	C. difficile, rotavirus
Pets	Dog feces	Yersinia enterocolitica
Turtles/reptiles	Non-typhoidal Salmonella
Other animals/pets	Campylobacter

Presentation

• Symptoms
  • common symptoms
    • dehydration
      • lethargy
      • feeling of thirst
    • diarrhea
      • foul-smelling along with stools that float
      • bloody diarrhea
      • watery diarrhea 
    • other enteric symptoms
      • nausea
      • vomiting
      • abdominal pain/cramping
• Physical exam
  • inspection
    • dry mucous membranes
    • sunken eyes
    • poor skin turgor
• delayed capillary refill

Studies

• Acute diarrhea does not routinely require laboratory evaluation, unless clinical presentation includes
  • high fever
  • bloody diarrhea
  • severe abdominal pain
  • requires hospitalization
  • elderly
  • immunocompromised status
• Serum labs
  • complete blood count
• Stool studies
  • ova and parasite examination
  • C. difficile toxin
  • leukocyte presence suggests enteroinvasive infection
  • pH <5.5 usually indicates viral illness and can also indicate lactase deficiency
  • culture
  • enzyme immunoassay for rotavirus and adenovirus antigens
• latex agglutination assay for rotavirus

Differential

• Chronic diarrhea, which lasts 4 weeks or more, suggests other etiologies, such as fat malabsorption syndrome

Chronic Diarrhea
Malabsorption syndromes	Celiac diseaseLactose intolerancePancreatic insufficiencyDiabetic neuropathy
Inflammatory bowel disease	Crohn diseaseUlcerative colitis
Other gastrointestinal causes	Microscopic colitisIrritable bowel syndrome
Endocrinological	CarcinoidGastrinoma
Drug-induced	QuinidineColchicineChemotherapy
Other	Severe combined immunodeficiencyArsenic poisoningVitamin C toxicityVitamin B3 deficiency

Treatment

• Medical
  • supportive care
    • modalities
      • oral rehydration
      • intravenous rehydration
      • electrolyte repletion
  • antibiotics
    • indication
      • for bacterial etiologies causing moderate or severe diarrhea and not responsive to rehydration
      • metronidazole or tinidazole for Giardia infections 
      • doxycycline for Vibrio cholera
      • oral vancomycin for C. difficile infection 
  • anti-motility agents
    • indication
      • not indicated for infectious diarrhea
    • modalities
      • loperamide
• bismuth salicylate

Complications

• Dehydration