Escherichia Coli (Or E. Coli) Is A Gram-Negative, Rod-Shaped,

1262 WordsMar 17, 20176 Pages
Escherichia coli (or E. coli) is a Gram-negative, rod-shaped, facultative anaerobic bacterium found in the intestinal tract of most species of mammals and birds. E. coli cells contain pili and a flagellum. As a Gram-negative bacterium, they also contain lipopolysaccharides in the outer cell membrane. Refer to Appendix 1 for a labelled diagram of an E. coli cell. The taxonomy of Escherichia coli is as follows: Domain Bacteria Kingdom Eubacteria Phylum Proteobacteria Class Gammaproteobacteria Order Enterobacteriales Family Enterobacteriaceae Genus Escherichia Species Escherichia coli (E. coli) Although most strains of E. coli are commensals, a small portion of strains are pathogenic in humans. The pathogenic strains can be grouped into…show more content…
Part B: Transmission As animals are continuously shedding E. coli bacteria through their feces, the immediate environments of these animals are contaminated by the bacteria. E. coli can spread from these environments to fertilized fields and crops as well as ground and surface water by way of slurry and manure. This transmission may also contaminate feed and drinking water which therefore transmits E. coli to other animals that were not present in the immediate environment of infection. Transmission usually occurs as the result of the introduction of E. coli containing feces into the oral cavity of the host. Known as fecal-oral transmission, this type of transmission is primarily responsible for the spread of E. coli from animals to humans. The transmission of E. coli to humans occurs by direct contact, ingestion of water or food contaminated by the spread of manure, or consuming undercooked meat after fecal contamination of the carcasses at the slaughterhouse. For a diagram of the transmission life cycle of E. coli, see Appendix 5. For a comprehensive diagram outlining the various transmission methods, refer to Appendix 6. The method of establishment in a host is dependent on the specific strain of pathogenic E. coli. Enterotoxigenic E. coli (ETEC) cells adhere onto the surface of the mucosa cells lining the small intestines of the host. ETEC can produce labile toxin (LT) and/or stable toxin (ST). These two enterotoxins cause secretion of fluid and result
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