A. Introduction. Although we might think of diarrhea as a nuisance, more than 5 million deaths per year worldwide can be attributed to this ailment.
a. Definition. Diarrhea is the excretion of more than 200 g of stool per day or more than three loose or watery bowel movements per day compared with baseline. Severe diarrhea consists of at least six loose or watery stools per day. Diarrhea is not a subjective experience of increased frequency or quantity of stool. However, patients often interpret any increase in the number of stools per day or an increase in the liquid nature of the stool as diarrhea. Therefore, quantification of stool is important.
b. Classification. Diarrhea can be classified based on the duration of symptoms as acute (<14 days in duration), persistent (14–29 days), or chronic (≥30 days). Because acute diarrhea occurs more frequently in hospitalized patients, it is the focus of this chapter.
B. Common Causes of Acute Diarrhea in Hospitalized Patients.
a. Infection. Diarrhea of an infectious etiology is the most common etiology in patients being admitted to the hospital with diarrhea. Clostridium difficile colitis warrants special consideration given the potential severity of this illness and the fact that patients can be either admitted with C. difficile colitis or develop this complication during hospitalization. It is the most common cause of fatal nosocomial diarrhea acquired in the hospital or a long-term care facility. C. difficile colitis should be considered in any patient with diarrhea who has been treated with antibiotics or chemoradiation; however, C. difficile colitis can also occur in patients without an obvious exposure.
Persistent, profuse diarrhea with evidence of systemic leukocytosis should prompt consideration of Clostridium difficile colitis.
b. Inflammation. Diarrhea resulting from an inflammatory process (e.g., inflammatory bowel disease, ischemic bowel disease) often presents with blood and pus in the stool. An infectious etiology must be ruled out to make this diagnosis.
c. Drugs, including laxatives, antacids containing magnesium, antibiotics, and colchicine, are often an overlooked cause of diarrhea, especially in long-term care settings.
d. Toxins, including heavy metals, seafood toxins, and mushroom toxins, can cause acute diarrhea.
e. Other. Impacted feces causing “overflow” diarrhea is common. Less common causes of acute diarrhea include carcinoid tumor, diabetic neuropathy, small intestinal bowel overgrowth, and thyrotoxicosis.
C. Approach to the Patient. Figure 29.1 provides an algorithm for evaluating patients with acute diarrhea.
a. History helps to narrow the differential diagnosis. If vomiting is a prominent symptom, then viral gastroenteritis or food poisoning is likely. One should ask exposure questions, including recent international travel; recent treatment with antibiotics, chemoradiation, proton pump inhibitors, or H2 receptor blockers; sexual history; work exposure; and immunocompromised state.
b. Evaluate volume status. Physical examination findings suggestive of dehydration include mental status changes, tachycardia, orthostatic hypotension, dry mucous membranes, and skin tenting—although signs may not be present unless severe hypovolemia exists. Obtain serum electrolytes, including creatinine, in older adults and patients who appear severely dehydrated.
c. Most cases of acute, infectious diarrhea are self-limited (with half lasting less than 1 day) and only need supportive care without a formal workup. Time thus helps differentiate which patients need a diagnostic workup from those who need the “tincture of time.”
d. Stool culture is not generally necessary but should be considered in the following settings: severe diarrhea, diarrhea that lasts more than 1 week, fever, dysentery (bloody diarrhea), and multiple cases that suggest an outbreak.
e. Stool for C. difficile (“C. diff”) toxin—should be sent when C. diff colitis is clinically suspected (three or more loose stools in 24 hours or concern of ileus with risk factors such as recent antibiotic use, hospitalization, advanced age, or history of inflammatory bowel disease). DO NOT send formed stools for testing or send stool in the absence of clinical suspicion of this disorder because testing does not distinguish between those with C. diff–associated diarrhea and those who are simply asymptomatic carriers.
a. Bland diet. Dairy foods, spicy foods, and caffeine should be avoided. The patient should follow the BRAT diet:
MNEMONIC: (“BRAT”) diet
c. Rehydration. Intravenous fluids may be necessary if the patient is unable to take liquids orally.
d. Pharmacologic therapy
i. Antimotility agents (e.g., loperamide). In some patients with infectious diarrhea, antimotility agents pose a theoretical risk for toxic megacolon and prolongation of illness. Infectious or inflammatory etiologies should be ruled out before using antimotility agents.
ii. Bismuth subsalicylate has antisecretory and antimicrobial properties and can be useful for traveler’s diarrhea or viral diarrhea.
iii. Antibiotics, if necessary, are usually given in 5- to 7-day courses. Note that antibiotics are contraindicated in the case of Shiga toxin–producing Escherichia coli because some antibiotics may increase the production of the toxin and therefore the risk for hemolytic uremic syndrome. For confirmed cases of C. difficile colitis, oral metronidazole is the initial antibiotic of choice. Refractory, relapsed, or severe cases may be treated with oral vancomycin.
Suggested Further Readings
Bagdasarian N, Rao K, Malani PN. Diagnosis and treatment of Clostridium difficile in adults: a systematic review. JAMA 2015;313:398–408.Find this resource:
Bartlett JG. Clinical practice. Antibiotic-associated diarrhea. N Engl J Med 2002;346:334–9. (Classic Article.)Find this resource:
DuPont HL. Clinical practice. Bacterial diarrhea. N Engl J Med 2009;361:1560–9.Find this resource: