Bacterial Diarrhea

Foodborne bacterial diarrhea is a common problem of backpackers, kayakers, divers - of anyone who ventures into the outdoors and is therefore associated with ingestion of fresh fruits and vegetables, travels to developing countries, practices inadequate hygiene, or even dines in public restaurants. Diagnosis and treatment of infectious diarrhea (bacterial, protozoal, viral, and other causes) is an essential skill for the wilderness medicine practitioner.

In an article (New England Journal of Medicine 2009;361:1560-1569) entitled "Bacterial Diarrhea," my good friend Dr. Herbert DuPont of the University of Texas School of Public Health and the Baylor College of Medicine provided a phenomenal update on the topic. There is a wealth of information in the article, so I will hit a few of the facts and figures that should be of greatest interest to this particular readership.

Campylobacter, nontyphoid Salmonella, Shiga toxin-producing E. coli, and Shigella bacteria are common causal agents of bacteria-induced diarrhea in the U.S. Other bacteria are more frequently associated with particular environments, such as Aeromonas in tropical regions. Plesiomonas shigelloides is associated with seafood ingestion and international travel.

The article was U.S.-focused. Acute watery diarrhea should bring to mind E. coli, Salmonella and Campylobacter. Bloody diarrhea ("dysentery") is suggestive of colitis. The four major U.S. causes, in descending order, are Shigella, Campylobacter, nontyphoid Salmonella and Shiga toxin-producing E. coli.

Food poisoning is the term used when a preformed toxin in good is eaten, which causes intoxication rather than an infection. A common culprit is Staphylococcus aureus. Others are Clostridium perfringens and Bacillus cereus.

Traveler's diarrhea can be caused by many different bacteria, but the most common is E. coli. Persons with traveler's diarrhea may be treated empirically with antibiotics without having their stool examined under the microscope or by stool culture. To prevent the disease, rifaximin in a dose of 200 mg once or twice a day taken with major meals while in the affected area appears to be effective. Indications for prophylaxis include an important trip, underlying illness that might be worsened by the disease, condition in which someone might be more prone to diarrhea, or suggestion that a person has increased susceptibility for some other reason.

Treatment recommendations are discussed. For all cases of diarrhea, attention to fluid and electrolyte replacement is essential. A diet of easily digestible food or a diet of bananas, rice, applesauce and toast is often recommended, but there is no evidence that such diets hasten recovery. It is important to keep the victim hydrated and nourished as best possible, which supports the concept of oral feeding. Drugs that diminish the number of bowel movements, such as loperamide, may be helpful. If the victim suffers from fever or dysentery, then antimotility drugs should only be used in combination with antibiotics.

This is an important and comprehensive review article for anyone interested in bacterial diarrhea. There are complete antibiotic recommendations, lists of complications, and discussion of areas of uncertainty. While the article is written for doctors, it has much information that can be understood and used effectively by laypersons.