DIARRHEA   31A

A 62-year-old woman presents to her primary care provider with complaints of 2 weeks of diarrhea, starting after a recent hospitalization for pneumonia. She describes the diarrhea as watery stool mixed with small amounts of blood, large in volume, and occurring seven to 10 times per day. She was treated in the hospital with antibiotics for her pneumonia and for this diarrheal episode received a recent course of a ciprofloxacin from an urgent care clinic without resolution. On physical examination, she has dry mucous membranes and a diffusely tender abdomen.

What are the salient features of this patient’s problem? How do you think through her problem?

Salient features: Frequent stools; 2-week time course; recent hospitalization and antibiotic use; large-volume watery stool with blood; no resolution with ciprofloxacin; dehydration and abdominal tenderness

How to think through: Acute diarrhea is defined as occurring for less than 2 weeks. Given that this patient was recently hospitalized and received two courses of antibiotics, what are the most likely causes of her diarrhea? (Direct medication toxicity vs. infectious diarrhea, specifically, C. difficile colitis or another hospital-acquired pathogen.) When after antibiotic exposure does diarrhea caused by C. difficile typically begin? (5–10 days, although the interval can be up to several weeks.) What are the next diagnostic steps? (Send C. difficile toxin assay immediately Stool culture for Campylobacter, Shigella, and Salmonella is reasonable. There are no risk factors for parasitic disease. A complete blood count and serum electrolytes and creatinine should be sent.) What is the next treatment step? (Because of the high prevalence of C. difficile—up to 20% of hospitalized patients are carriers—and the potential severity of the complications, empiric antibiotic treatment for C. difficile is appropriate. Her dry mucous membranes on examination suggest dehydration, and based on her vital signs and overall assessment, readmission to the hospital for supportive care should be strongly considered.) What are the serious sequelae of C. difficile colitis? (Fulminant colitis with systemic toxicity; toxic megacolon.) What clinical signs would prompt imaging and escalation of care? (High fever, severe pain, leukocytosis [white blood cell count of 15,000/mcL is typical for mild to moderate disease; 40,000/mcL is more consistent with fulminant disease], and shock.)

DIARRHEA   31B

What are the essentials of diagnosis and general considerations regarding diarrhea?

Essentials of Diagnosis

Acute diarrhea has a duration of less than 2 weeks; chronic diarrhea is present for more than 4 weeks

Traveler’s diarrhea is usually a benign, self-limited disease occurring about a week into travel

General Considerations

Acute diarrhea is most commonly caused by infectious agents, bacterial toxins, or drugs.

Recent exposures, ingestions, medical history, and travel may suggest causes of diarrhea.

Inflammatory diarrhea is distinguished from noninflammatory diarrhea by the presence of fecal blood and leukocytes.

Medications that can commonly cause diarrhea include metformin, allopurinol, orlistat, selective serotonin reuptake inhibitors, cholinesterase inhibitors, proton pump inhibitors, and nonsteroidal antiinflammatory drugs.

Osmotic diarrheas resolve during fasting; secretory diarrheas do not.

Immunocompromised patients are susceptible to many infectious causes of diarrhea.

Traveler’s diarrhea is a risk factor for development of irritable bowel syndrome.

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