Gastroenteritis is inflammation of the stomach and intestines; colitis is inflammation of the colon. Viruses are the most common cause, followed by bacteria and parasites. Incidence of the various infections varies by age, sex, location, and vaccine availability; vaccination has reduced rotavirus infections by as much as 90% in children. Postinfectious complications include irritable bowel syndrome (IBS) and lactose intolerance. Approximately 9% of patients with acute gastroenteritis or colitis develop postinfectious IBS, which accounts for more than 50% of all IBS cases. The diagnostic approach to gastroenteritis and colitis varies with symptom severity. Microbial studies are not needed with mild symptoms that resolve within a week, but longer-lasting or more severe symptoms (including bloody stool) warrant microbial studies. In addition, recent antibiotic exposure should prompt testing for Clostridioides difficile. Multiplex antimicrobial testing is preferred; stool cultures and microscopic stool examinations are no longer first-line tests. Management depends on severity. Patients with mild or moderate symptoms are treated with oral hydration if tolerated; nasogastric or intravenous hydration are used for those with more severe illness. In addition, antiemetic, antimotility, and/or antisecretory drugs can be used for symptom control. Antimicrobial therapy is indicated for C difficile infections, travel-related diarrhea, other bacterial infections with severe symptoms, and parasitic infections.
Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.