Gastrointestinal Infections

Amebiasis

Description of Medical Condition Amebiasis is caused by the intestinal protozoan, Entamoeba histolytica. Infection results from ingestion of fecally contaminated food, such as garden vegetables or by direct fecal-oral transmission. Most persons are asymptomatic or have minimal diarrheal symptoms. In a few patients, invasive intestinal or extraintestinal (e.g., liver, and less commonly kidney, bladder, male or female genitalia, skin, lung, brain) infection results. Amebic abscess of the liver may develop during the acute attack or 1 -3 months later; symptoms may be abrupt or insidious. Entamoeba histolytica has been divided into ‘pathogenic” and “nonpathogenic” strains. The pathogenic strains commonly cause invasive infection while the noninvasive strains cause only asymptomatic intestinal infection. …

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Gastrointestinal Infections

Gastrointestinal infections are among the more common causes of morbidity and mortality around the world. Most are caused by viruses and some are caused by bacteria or other organisms. In underdeveloped and developing countries, acute gastroenteritis involving diarrhea is the leading cause of mortality in infants and children younger than 5 years of age. In the United States, there are approximately 211 million episodes of acute gastroenteritis each year, causing over 900,000 hospitalizations and over 6000 deaths. Rehydration therapy Fluid replacement is the cornerstone of therapy for diarrhea regardless of etiology. Initial assessment of fluid loss is essential for rehydration. Weight loss is the most reliable means of determining the extent …

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Bacterial Infections

The bacterial species most commonly associated with gastrointestinal infection and infectious diarrhea in the United States are Shigella spp., Salmonella spp., Campylobacter spp., Yersinia spp., Escherichia spp., Clostridium spp., and Staphylococcus spp. Antibiotics are not essential in the treatment of most mild diarrheas, and empirical therapy for acute gastrointestinal infections may result in unnecessary antibiotic courses. Enterotoxigenic (cholera-like) Diarrhea Cholera (Vibrio cholerae) Vibrio cholerae is the organisms that most often causes human epidemics and pandemics. Four mechanisms for transmission have been proposed: animal reservoirs, chronic carriers, asymptomatic or mild disease victims, or water reservoirs. TABLE. Clinical Assessment of Degree of Dehydration in Children Based on Percentage of Body Weight Lossa Variable …

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Invasive (dysentery-like) Diarrhea

Bacillary Dysentery (Shigellosis) Four species of Shigella are most often associated with disease: S. dysenteriae type I, S. flexneri, S. bovdii, and S. sonnei. Poor sanitation, poor personal hygiene, inadequate water supply, malnutrition, and increased population density are associated with increased risk of Shigella gastroenteritis epidemics, even in developed countries. The majority of cases are thought to result from fecal-oral transmission. Shigella spp. cause dysentery upon penetrating the epithelial cells lining the colon. Microabscesses may eventually coalesce, forming larger abscesses. Some Shigella species produce a cytotoxin, or shigatoxin, the pathogenic role of which is unclear although it is thought to damage endothelial cells of the lamina propria, resulting in microangiopathic changes …

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