Infectious Diseases: February 15, 2004

John Bartlett, MD


February 17, 2004

In This Article

Acute Infectious Diarrhea

Thielman NM, Guerrant RL. Clinical practice. Acute infectious diarrhea. N Engl J Med. 2004;350:38-47. This is a review of acute infectious diarrhea as summarized below:

US data: 1.4 episodes/person/year, 900,000 hospitalizations, and 6000 deaths/year.

Microbiology: FoodNet, a CDC surveillance network that collects data on 37 million people in 9 states, showed the following incidence (cases/100,000 population): Salmonella - 16.1; Campylobacter - 13.4; Shigella - 10.3; Escherichia coli 0157-1.7, and Cryptosporidium-1.4.

Cost of evaluation: Six studies from 1980-97 showed a yield from stool cultures of 1.5% to 5.6%, giving an estimated cost of $952 to $1200/positive culture. Most diarrheal illnesses are self limited or viral, and about half last less than 1 day. Thus, symptoms of more than 24 hours' duration are usually required to justify an etiologic evaluation. Common causes in the wintertime are noroviruses in families and in outbreaks and rotaviruses in children; these usually last 1-3 days and are self-limited.

Fecal leukocytes: In developed countries, the sensitivity and specificity of fecal white blood cell analysis for inflammatory diarrhea are 0.7 and 0.8, respectively, and for fecal lactoferrin are 0.9 and 0.8, respectively.

Bloody diarrhea: This suggests Entamoeba histolytica in patients returning from endemic areas or shiga-toxin producing E coli.

Inflammatory diarrhea: The treatable causes are Shigella, Salmonella, Campylobacter jejuni, Clostridium difficile, or E histolytica.

Rehydration: Most adults should simply be encouraged to drink fluids and take salt and soups or salted crackers. For severe dehydration, the recommendation is for the reduced-osmolarity formula for children or the standard formulation recommended by WHO. There should be avoidance of milk products due to transient lactase deficiency.

Antidiarrheal products: Only 3 have good evidence of efficacy and safety including loperamide, bismuth subsalicylate, and kaolin. The preferred antimotility agent is loperamide, which has the advantage compared to other opiates of not penetrating the CNS, so there is little or no potential for addiction. These drugs are felt to be contraindicated for shigellosis, C difficile with toxic megacolon, and hemolytic uremic syndrome (HUS) with E coli 0157.

Diagnostic evaluation: The authors recommend an evaluation process that is described in 6 steps as follows:

Step 1 – Initial assessment: Assess dehydration, duration (with emphasis on symptoms >1 day), and evidence of "inflammatory diarrhea" (fever, stool blood, tenesmus).

Step 2 – Symptomatic treatment: Rehydration; consider bismuth subsalicylate or loperamide if diarrhea is not bloody or inflammatory.

Step 3 – Management by setting: Evaluate according to epidemiology (food, antibiotics, sexual activity, travel, day-care attendance, other illnesses, outbreaks, season) and clinical clues (bloody diarrhea, abdominal pain, dysentery, wasting, fecal inflammation).

Step 4 – Stool sample for analysis: If diarrhea is severe, bloody, inflammatory, persistent, or part of an outbreak, consider the probabilities as follows:

  • Travelers: Test for Salmonella, Shigella, C jejuni, E coli 0157, or C difficile (if there has been exposure to antibiotics)

  • Nosocomial diarrhea: C difficile (only this agent, unless outbreak or > 65 years; with immunocompromise – Salmonella, Shigella, and C jejuni; if bloody – E coli 0157:H7).

  • Persistent diarrhea > 7 days: Giardia, Cryptosporidium, Cyclospora, Isospora, and screen for inflammation

  • Immunosuppressed: Microsporidia, Mycobacterium avium, cytomegalovirus (CMV)

Step 5 – Antibiotic therapy: If indicated (see below).

Step 6 – Report the reportable: Cholera, Cryptosporidium, Giardia, Salmonella, Shigella, E coli 0157. In outbreaks: save culture plates, isolates, and relevant food and water (-70° C).

Etiologic agents:  Table 15 , Table 16 , and Table 17 summarize the clinical features of the most important treatable pathogens.


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