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For further information, see CMDT Part 15-06: Diarrhea

Key Features

Essentials of Diagnosis

  • Diarrhea of less than 2 weeks' duration is most commonly caused by invasive or noninvasive pathogens and their enterotoxins

Acute noninflammatory diarrhea

  • Watery, nonbloody

  • Usually mild, self-limited

  • Caused by a virus or noninvasive bacteria

  • Diagnostic evaluation is limited to patients with diarrhea that is severe or persists beyond 7 days

Acute inflammatory diarrhea

  • Blood or pus, fever

  • Usually caused by an invasive or toxin-producing bacterium

  • Diagnostic evaluation requires routine stool bacterial testing (including Escherichia coli O157:H5 and O157:H7) in all and testing as clinically indicated for Clostridioides difficile and parasites

General Considerations

  • Most commonly caused by infectious agents, bacterial toxins (Table 30–3), or drugs

  • Recent illnesses in family members suggests infectious diarrhea

  • Community outbreaks (schools, nursing homes, cruise ships) suggest viral etiology or common food source

  • Ingestion of improperly stored or prepared food implicates toxin-secreting or invasive bacteria

  • Exposure to unpurified water suggests Giardia or Cryptosporidium

  • Large Cyclospora outbreaks have been traced to contaminated produce

  • Recent travel abroad suggests "traveler's diarrhea"

  • Antibiotic administration suggests C difficile colitis

  • HIV infection or sexually transmitted diseases suggest AIDS-associated diarrhea

  • Proctitis and rectal discharge suggest gonorrhea, syphilis, lymphogranuloma venereum, and herpes simplex

Table 30–3.Acute bacterial diarrheas and “food poisoning” (listed in alphabetical order).

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