tailieunhanh - Chapter 040. Diarrhea and Constipation (Part 4)

Acute Diarrhea More than 90% of cases of acute diarrhea are caused by infectious agents; these cases are often accompanied by vomiting, fever, and abdominal pain. The remaining 10% or so are caused by medications, toxic ingestions, ischemia, and other conditions. INFECTIOUS AGENTS Most infectious diarrheas are acquired by fecal-oral transmission or, more commonly, via ingestion of food or water contaminated with pathogens from human or animal feces. In the immunocompetent person, the resident fecal microflora, containing 500 taxonomically distinct species, are rarely the source of diarrhea and may actually play a role in suppressing the growth of ingested pathogens. . | Chapter 040. Diarrhea and Constipation Part 4 Acute Diarrhea More than 90 of cases of acute diarrhea are caused by infectious agents these cases are often accompanied by vomiting fever and abdominal pain. The remaining 10 or so are caused by medications toxic ingestions ischemia and other conditions. INFECTIOUS AGENTS Most infectious diarrheas are acquired by fecal-oral transmission or more commonly via ingestion of food or water contaminated with pathogens from human or animal feces. In the immunocompetent person the resident fecal microflora containing 500 taxonomically distinct species are rarely the source of diarrhea and may actually play a role in suppressing the growth of ingested pathogens. Disturbances of flora by antibiotics can lead to diarrhea by reducing the digestive function or by allowing the overgrowth of pathogens such as Clostridium difficile Chap. 123 . Acute infection or injury occurs when the ingested agent overwhelms the host s mucosal immune and nonimmune gastric acid digestive enzymes mucus secretion peristalsis and suppressive resident flora defenses. Established clinical associations with specific enteropathogens may offer diagnostic clues. In the United States five high-risk groups are recognized 1. Travelers. Nearly 40 of tourists to endemic regions of Latin America Africa and Asia develop so-called traveler s diarrhea most commonly due to enterotoxigenic or enteroaggregative Escherichia coli as well as to Campylobacter Shigella Aeromonas norovirus Coronavirus and Salmonella. Visitors to Russia especially St. Petersburg may have increased risk of Giardia-associated diarrhea visitors to Nepal may acquire Cyclospora. Campers backpackers and swimmers in wilderness areas may become infected with Giardia. Cruise ships may be affected by outbreaks of gastroenteritis caused by agents such as Norwalk virus. 2. Consumers of certain foods. Diarrhea closely following food consumption at a picnic banquet or restaurant may suggest infection with .