Gastroenteritis

Gastroenteritis is inflammation of the gastrointestinal tract caused by ingestion of pathogens or their toxins in contaminated food or water. The most common etiologic agents in the United States are viruses, especially Rotaviruses in children and Norwalk-type viruses in adults. Common bacteria that cause gastroenteritis include Escherichia coli, Campylobacter jejuni, Salmonella species, Shigella sonnei, and Vibrio species. The toxins of Staphylococcus aureus, Bacillus cereus, and Clostridium difficile may also cause disease. Patients with gastroenteritis experience abdominal pain and diarrhea with or without vomiting or fever. In the majority of cases, symptoms are brief, and patients do not require medical attention. If symptoms are prolonged or severe, diagnostic testing and treatment may be indicated. Microscopic examination of stool for leukocytes, stool culture, and testing for C. difficile toxin are the most valuable diagnostic studies. Oral rehydration therapy is the mainstay of treatment of acute gastroenteritis, and antibiotics are seldom required. When necessary, the most useful choices for treatment of acute infectious diarrhea include trimethoprim-sulfamethoxazole, quinolones, and macrolide antibiotics. Metronidazole is efficacious for treatment of pseudomembranous colitis. Treatment with nonantibiotic medications, such as bismuth subsalicylate, loperamide or diphenoxylate with atropine offers symptomatic relief in cases of noninflammatory infectious diarrhea.