Gastroenteritis

– A self-limiting, acute inflammation of the stomach and small intestine caused by ingestion of food, water, or feces contaminated with pathogenic agents, parasites, or toxins.

Causes and Incidence

Causative agents include bacterial and viral pathogens, such as Campylobacter coli, Escherichia coli, Salmonella and Shigella organisms, Norwalk virus, and rotavirus; parasites, such as Ascaris, Enterobius, and Trichinella species; and toxins, such as poisonous plants or toadstools, arsenic, lead, and mercury. Inability to digest and absorb carbohydrates has also been implicated as a cause, although it is rare and the mechanism is poorly understood. Various forms of gastroenteritis are common manifestations worldwide and are often mistaken for food poisoning. Bacterial, parasitic, and viral types of gastroenteritis are infectious and can be transmitted directly or indirectly.

Disease Process

The pathologic conditions depend on the causative agent. Toxigenic agents, such as some E. coli and Shigella strains, release an exotoxin that impairs intestinal absorption. Invasive pathogens, such as some Shigella and Salmonella species and E. coli, penetrate the mucosa of the small bowel, causing cellular destruction, necrosis, ulceration, bleeding, and exudation of protein-rich fluid. Pathogens such as rotaviruses attach to the mucosal wall and destroy cells in the intestinal villa, causing malabsorption of electrolytes. Parasites and toxins also interfere with intestinal functioning. The general result of all pathogenic agents is increased GI motility and increased secretion of fluids and electrolytes.

Symptoms

The onset is often sudden, with abdominal pain and cramping, nausea and vomiting, diarrhea with or without blood and mucus, anorexia, general malaise, and muscle aches. Dehydration, hypokalemia, and hyponatremia occur with persistent vomiting and diarrhea.

Potential Complications

Dehydration, shock, vascular collapse, and renal failure, in rare instances leading to death, are complications of gastroenteritis. Infants, small children, the elderly, and debilitated individuals are at greatest risk.

Diagnostic Tests

Diagnosis relies on identification of the causative agent through stool and blood cultures, Gram’s stain, and direct swab rectal cultures.

Treatments

Surgery
None.

Drugs
Antidiarrheal agents for all types; antiemetics, except for viral or bacterial gastroenteritis, in which impairment of GI motility is avoided; antiinfective agents for bacterial gastroenteritis with systemic involvement (not generally recommended for simple gastroenteritis, because these drugs may prolong the carrier state and contribute to the emergence of drug-resistant organisms).

General
Rest; increased fluid intake; electrolyte replacement; bland diet.