What bacterium is associated almost exclusively with antibiotic-associated diarrhea?
GI Diseases
Introduction to Gastrointestinal Diseases - Review Mode - Quiz mode
Introduction to Gastrointestinal Infections
Diarrheal diseases are one of the leading causes of death worldwide, with poverty, lack of sanitation, and lack of good nutrition contributing to the vicious cycle of disease, malnutrition, and death. World wide, rotaviruses, E. coli, and Campylobacter jejuni are the leading causes of these illnesses. Amoeba and parasitic worms are also significant problems in many countries. In the US, viruses, Campylobacter, Shigella, and Salmonella are major causes. Pathogenic E. coli is difficult to test for due to the presence of an abundant non-pathogenic intestinal flora containing E. coli, although tests are available for specific strains such as E. coli 0157:H7. C. difficile is a nosocomial cause of a serious diarrhea.
While not an infection, food intoxication (food poisoning) is a common cause of illness in the US and other countries. The term food poisoning should be reserved for true food intoxications, where bacteria need not be ingested, or if ingested, need not colonize; however, infections acquired from food are often (incorrectly) called food poisoning. The diarrheal infections are of two main types, 1) secretory or watery, and 2) inflammatory. The latter is sometimes referred to as dysentery. The pathogenesis of the two types is fundamentally different and contributes to their different symptomology. In secretory or watery diarrhea a bacterial toxin or virus alters the fluid balance in the intestines.
In inflammatory diarrhea there is invasion of the intestinal wall with subsequent inflammation and release white blood cells and sometimes red blood cells into the lumen of the intestine. Enteric fever, such as typhoid fever, is a systemic disease that begins in the GI tract, but may not have any GI symptoms. In enteric fevers, the organisms invade through the intestine and become systemic. Chapter 8, pp 241 to 262, of Infectious Diseases in 30 Days by F.S. Southwick (McGraw-Hill, 2003) discusses these diseases from the point of view of a physician in the US (note that Salmonella nomenclature has been changed since this was written, see the Bugs index). After reading this, or the introduction to GI diseases in any Microbiology text book, you should be able to answer the following questions.
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Question 1 - Single Best Answer
What is the primary non-specific host defense protecting the GI tract?
Answer with Explanation:A) non-specific phagocytes
B) killer T-cells
C) complement
D) stomach acid
E) constant mucosal surface washing
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D) stomach acid
CORRECT!
Yes! Organisms that are resistant to stomach acid require much lower inocula than organisms that are not. Normal flora also help protect.
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