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Chapter 5 : Escherichia coli: Enteric and Extraintestinal Infections
Category: Clinical Microbiology
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Among the microbial flora that naturally inhabit the human gastrointestinal tract, Escherichia coli is the most abundant facultative anaerobe. While members of the family Enterobacteriaceae are natural inhabitants of the gastrointestinal tract and are abundant in the environment, there are particular predisposing factors and circumstances that allow both intestinal and extraintestinal infections to occur in community and nosocomial settings. In developing countries of Asia, Latin America, and Africa, where diarrhea is one of the most lethal threats to children under the age of five, enteropathogenic E. coli (EPEC) is a major cause of infantile diarrhea. A study describing early predictors of adverse outcomes following neonatal bacterial meningitis found that elevated total protein in the initial cerebrospinal fluid (CSF) analysis, as well as a CSF-to-blood glucose ratio of < 0.5, corresponded with an adverse outcome. The current definition of postinfectious irritable bowel syndrome (IBS) according to the Rome II criteria, which most studies follow, is the new onset of symptoms developing acutely after an illness characterized by two or more of the following: fever, vomiting, acute diarrhea, or positive stool culture. There are two main types of Shiga toxins, and Shiga toxin-producing E. coli (STEC) (O157 and non-O157 alike) that produce both Stx2 and Stx1, or Stx2 alone, are more likely to be associated with HUS than those that produce Stx1 only. Prebiotic oligosaccharides may also have similar applications for EPEC. Clearly, new and innovative approaches will be required to reduce the burden of E. coli infections and their sequelae.
A transmission electron micrograph demonstrating the typical attaching and effacing effect on polarized human intestinal epithelial cells infected with EPEC. Bar, 1 μm. (Reprinted from the Journal of Clinical Investigation [ 111 ] with permission from the publisher.)