Bacterial Diarrhea

N Engl J Med 2009;361:1560-9.

CLINICAL PRACTICE

Clinical Problem

• More than 5.2 million cases of bacterial diarrhea that occur each year in the US, estimated 46,000 hospitalizations and 1,500 deaths each year in US.

• The 4 most commonly reported bacterial enteropathogens in the US:1. Campylobacter2. Salmonella3. Shiga toxin-producing E. Coli4. Shigell

Evaluation

• Stool culture should be obtained from all patients with – severe diarrhea (passage > 6 unformed stools per day)– diarrhea of any severity that persists for longer than a week – fever– dysentery– multiple cases of illness that suggest an outbreak

• Stool cultures are not routine in most cases of watery diarrhea or traveler’s diarrhea because of the low yield of bacterial pathogens.

Conditions Associated with Bacterial Diarrhea

• Acute Watery Diarrhea

• Dysentery

• Food Poisoning

• Traveler’s Diarrhea

• Nosocomial Diarrhea

Acute Watery Diarrhea

• Clinically nonspecific!– Most bacterial and nonbacterial enteropathogens produce acute

watery diarrhea

• Detectable enteric pathogens is identified in fewer than 3% of cases in the US.

• Most laboratories stool culture are set up to routinely look for shigella, salmonella, and campylobacter.

• Many of the potentially important agents that cause watery diarrhea are not detectable by routine laboratory tests; these agents include entero-toxigenic E. coli, entero-aggregative E. coli, entero-invasive E. coli, non-choleraic vibrios, and noroviruses.

Dysentery

• Passage of bloody stools suggests possible bacterial colitis. • Major causes of bloody diarrhea in the US:

1. Shigella2. Campylobacter3. Salmonella4. Shiga toxin-producing E. coli

• Severe abdominal pain and cramps and passage > 5 unformed stools per 24 hours in the absence of fever

• Watery diarrhea becomes bloody in 1 to 5 days in 80% of patients• Shiga toxin-producing E. coli is the main cause of renal failure in

childhood• 2/3 of children with the hemolytic-uremic syndrome require

dialysis; mortality rate: 3 to 5%

Food Poisoning

• Food poisoning is the term used when a preformed toxin in food is ingested, resulting in an intoxication rather than an enteric infection.

• Staphylococcus aureus causes vomiting within 2 to 7 hours after the ingestion of improperly cooked or stored food containing a heat-stable preformed toxin.

• Most cases of food poisoning are of short duration, with recovery occurring in 1 to 2 days. The diagnosis is made in nearly all cases clinically without laboratory confirmation.

Traveler’s Diarrhea

• Traveler’s diarrhea occurs when persons from industrialized regions venture into developing tropical and semitropical areas with reduced levels of personal and food hygiene.

• Bacterial enteropathogens cause up to 80% of cases.• E. coli account for more than half of cases occurring

in Latin America, Africa, and South Asia.• Campylobacter, shigella, and salmonella are relatively

more important causes of traveler’s diarrhea in Asia than in the other high-risk regions.

Traveler’s Diarrhea

• Patients with traveler’s diarrhea should be treated empirically with antibiotics without stool examination.

• Most authorities recommend rifaximin 200 mg once or twice a day (with major meals) while the person is in an area of risk.

• Alternative regimen is two tablets of bismuth subsalicylate with each meal and at bedtime.

• Indications for the use of chemoprophylaxis– important trip

(the purpose of which might be ruined by a short-term illness)– underlying illness that might be worsened by diarrhea (e.g.,

CHF) – persons more susceptible to diarrhea (e.g., use of daily PPI therapy)– previous bouts of traveler’s diarrhea

Nosocomial Diarrhea

• C. difficile accounts for a minority of antibiotic-associated and hospital-associated diarrhea, it should be considered in patients with clinically significant diarrhea (passage > 3 unformed stools per day), toxic dilatation of the colon or otherwise unexplained leukocytosis, or both.

• Risk factors for C. difficile diarrhea:– Advanced age and coexisting conditions– alteration of intestinal flora by antimicrobial agents– probably host genetics

Treatment

1. Fluid and electrolyte replacement2. Easily digestible food3. Antimotility drugs such as loperamide and

diphenoxylate hydrochloride4. Antimicrobial agents

Salmonellosis

• Bacteremia complicates the infection in approximately 8% of normal healthy persons.

• Risk factors:– Extremes of age (younger than 3 months and 65 years

or older)– corticosteroid use– Inflammatory bowel disease– immunosuppression– Hemoglobinopathy including sickle cell disease– hemodialysis

Shiga toxin-roducing E. coli

• Some antibacterial drugs, including fluoroquinolones and trimethoprim-sulfamethoxazole, may increase the risk of hemolytic–uremic syndrome.

• Most authorities recommend supportive treatment only in patients with Shiga toxin-producing E. coli infection.