Bacterial gastroenteritis in adults

What Is It?

Gastroenteritis is an inflammation of the stomach and small intestine that produces diarrhea, cramps, nausea and other symptoms of digestive upset. In adults, the two most common causes of gastroenteritis are viral infections and food poisoning:

• Viral gastroenteritis — In otherwise healthy adults, viral infections of the digestive tract are often responsible for mild episodes of gastroenteritis. These viral infections include the Norwalk virus, rotaviruses, adenoviruses and other agents. They typically spread when someone either touches an infected person's stool or touches surfaces contaminated with infected stool. For this reason, health-care personnel and child-care workers have an especially high risk of viral gastroenteritis, particularly if they do not wash their hands thoroughly after dealing with soiled diapers, bedpans or bathroom fixtures. In some circumstances, the agents that cause viral gastroenteritis also can be carried in water or food, especially in drinking water or commercial shellfish that have been contaminated by sewage runoff. Infected food handlers who don't follow proper sanitary procedures also can spread viral gastroenteritis in meals served in restaurants and cafeterias. Viral gastroenteritis often spreads very easily in institutions and other situations where people live in close quarters, such as prisons, nursing homes, cruise ships, schools, college dorms and public campgrounds.
• Food poisoning — Food that has been prepared or stored improperly can grow bacteria on its surface, and these bacteria sometimes produce irritating chemicals called toxins. If a person eats the germ-filled food, symptoms of gastroenteritis are triggered either by the bacteria themselves or by their irritating byproducts. Symptoms from a toxin typically begin within a few hours. Symptoms from the bacteria can occur within a few days.

Each year in the United States, millions of people develop gastroenteritis by eating contaminated food, while millions more suffer from mild bouts of viral gastroenteritis. In otherwise healthy adults, both forms of gastroenteritis tend to be mild and brief, and many episodes are never reported to a doctor. However, in the elderly and people with weakened immune defenses, gastroenteritis sometimes can produce dehydration (abnormally low levels of body water) and other dangerous complications. Even in robust adults, certain types of aggressive bacteria occasionally cause more serious forms of food poisoning that can produce high fever and severe gastrointestinal symptoms.

Symptoms

In adults, symptoms of gastroenteritis typically include mild diarrhea (fewer than 10 watery stools daily), cramps, low-grade fever (below 101 degrees Fahrenheit), headache, nausea and sometimes vomiting.