Example Of Research Paper On E. Coli
E. coli is a representative of the normal bacterial composition (microflora) of the human gastrointestinal tract. Escherichia coli infant receives from his mother at birth, and then multiplies and persists throughout life. In the large intestine, where most of these bacteria are localized, they perform some very important functions: protection against pathogens and curbing the growth of opportunistic pathogens; synthesis of vitamin K, B2, B3, B5, B6, B9, B12; it breaks down milk sugar (lactose); involved in the digestion of proteins and carbohydrates; involved in the processing of cholesterol, bile and fatty acids; assimilate oxygen, contributing to the development of lactobacilli and bifidobacteria. (Cohen, S., 1972).
E. coli is a normal inhabitant of the human gut. Only under special circumstances it may be pathogenic. Pathogenicity is especially pronounced in some species of microorganism. These types of pathogenic E. coli show their Virulence mainly in children from an early age (the first year, especially the first few months of life). They may be in the child's intestine without causing any signs of illness, and to show their Virulence only with a decrease in resistance to the child's body, which occurs under the influence of various factors weaken. But more types of pathogenic E. coli transmitted from other humans (patients, carriers) the same ways as for other intestinal infections. In unfavorable hygienic conditions in the children's collective coli infection can take on the character outbreak.
E. coli is a heterotrophic organism, which means that it gets its food from another source. This source is the host organism. And from their master, they get carbon through the biosynthesis of organic molecules trapped in the body of the host. Carbon is essential for E. coli, because the bacterial cell consists almost entirely of carbon molecules associated with other important elements. E. coli, in cell division, uses the asexual reproduction, because there is no transfer of genetic material; bacteria simply by making an exact copy of itself. An individual bacterium begins this process of cell elongation, whereupon nearly exact replication of the genome occurs in two identical copies. Mutation and errors may occur during replication, genetic, but usually in small quantities, and have little effect on the bacteria. Partitions are formed, and the cell divides equally cellular components and one copy of the parental genome is in each side. Cell divides, leaving two copies of the original bacterium called daughter cells. E. coli cells are divided by the constriction, as well as cells of other gram-negative bacteria. In the initial stages of cell division occurs ligation nucleoid and formation of looping cytoplasmic membrane at the site of the future waist (Doyle, R, 2000).
In E. coli there are more than 700 serotypes. They are based on three different antigens: Antigen O, which is derived from the cell wall antigen of H which is derived from flagella using the mobility, K antigen, which is a derivative of a polysaccharide capsule that is secreted. Pathogenic E. coli are divided into 4 groups: enteropathogenic (EPEC), enetrotoxygenic (ETEC), enteroinvasive (EIEC) and enterohaemorrhagic (EHEC or VTEC).
Enterotoxigenic Escherichia colonizes the small intestine and produce cholera-like disease. Carriage after recovery is not formed. It most often found in India. Sources of infection are food and water. The peak incidence occurs in children from one year to three years. Enteropathogenic Escherichia cause infection, symptoms of the disease are similar to salmonellosis. Children are most likely to nosocomial strains of EPEC, or become infected through contact-household (towels, sheets). Adults acquire enteropathogenic Escherichia through products. In the United States enteropathogenic E. coli is ranked as first among intestinal diseases of children. Symptoms: watery diarrhea, nausea, vomiting. The disease is long - up to 15 days. The carrier can be formed after recovery (Doyle, R., 2000).
The incubation period for E. coli infection lasts 3-6 days. The disease is characterized by lesions mainly of the small intestine. The disease usually begins acutely, there is vomiting, frequent loose, watery stools, sometimes with a small amount of mucus; in some patients the fever and symptoms of intoxication. In severe cases of intoxication may be accompanied by severe dehydration, appear characteristic of severe toxic for dysentery. The disease often has a fluctuating course with periods of improvement, replaced by new exacerbations of symptoms. Treatment of patients with intestinal infections, even with a light within them, must necessarily be prescribed by the doctor. The earlier treatment is started, the more reliable its success. The best results are obtained by treatment administered in a hospital; severe toxic forms can be successfully treated only in a hospital.
The most dangerous, but fortunately, most rare group is enterohaemorrhagic Escherichia. This type includes only one serogroup (for now) - O157: H7. It was first discovered in the 80s and the first outbreak occurred in the United States (in a nursing home, through bad fried burgers). Then it happened in Japan. And in one office building sick almost 1000 people (they ate cuttlefish, which were caught in the coastal zone). 30 years, humanity has forgotten about this nightmare, but in 2011, Europe has stirred news about the epidemic of enterohaemorrhagic Escherichiacoli. Rumor has it that the origin of the EHEC is artificial (bacteriological weapon or bad experiences on genetic modification), but it's just a guess. Pathogenicity factor is a toxin, which is superior to the toxicity of shigellosis hundreds of times. "Habitat" is the large intestine. The clinical picture of the disease is as follows: abdominal pain, diarrhea, cholera, which within a few hours turns into bloody diarrhea. If no acute renal failure, in conjunction with a low content of platelets and anemia (all called hemolytic uremic syndrome, or HUS), then for one - two weeks, the patient is treated Detoxication drugs. Treatment with antibiotics is not recommended! In the case of HUS mortality is very high - up to 100% (Itakura, K., 1977).
E. coli plays an important role in contemporary industrial microbiology and biological engineering. The work of Herbert Boyer and Stanley Norman Cohen on E. coli, using plasmids and restriction enzymes to create recombinant DNA, is at the origin of modern biotechnology. (Cohen, S. 1972). Establishing a causal role in the occurrence of coliform acute intestinal diseases is quite difficult, because these organisms are widespread in nature, always present in the intestines of healthy humans and animals, are very resistant to various physical and chemical factors and are able to develop on a wide variety of environments, including on food products. E. coli are essentially human commensal and an important factor for the antagonistic putrefactive microorganisms, limiting their development in the intestine. It is characteristic that the number of microbes various portions of the gastrointestinal tract of healthy human differ sharply. The number of microorganisms increases from the stomach to the large intestine. In normal operation, gastric microflora it is almost completely absent. Gastric juice is extremely pronounced antibacterial properties. In the large intestine contains a huge number of microbes. Preventive measures are reduced to comply with sanitary-hygienic regime and rules of personal hygiene. Specific prophylaxis is not carried out. Used for the treatment of chloramphenicol, neomycin and other antibiotics. In chronic infections and bacteriophages used autovaccines.
Cohen, S. (1972). Nonchromosomal Antibiotic Resistance In Bacteria: Genetic Transformation Of Escherichia Coli By R-Factor DNA. Proceedings of the National Academy of Sciences, 2110-2114.
Doyle, R. (2000). Glycomicrobiology. New York: Kluwer Academic/Plenum.
Itakura, K., Hirose, T., Crea, R., Riggs, A., Heyneker, H., Bolivar, F., & Boyer, H. (1977). Expression in Escherichia coli of a chemically synthesized gene for the hormone somatostatin. Science, 1056-1063.
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