Escherichia Coli - Research Paper Example

 ESCHERICHIA COLI Introduction: Escherichia coli is a bacterium which is referred to as an enterobacteriacea that is a bacteria that exists normally in the intestine of human and animals. This bacterium which exists in the form of gram negative rods has been named after the man, Theodor Escherich who discovered them in the year 1885. This bacterium is not completely aerobic that is it can survive in the presence of oxygen and it also has the capability to exist in the absence of oxygen by the process of fermentation. E. coli also has the property of movement though there are certain forms of the bacteria that form exceptions and do not move. The mobility is provided to it by flagellum, which is referred to as peritrichous flagella that is present on all sides of the bacteria. The bacterium does not have the property of forming spores. The bacterium has three antigens present. The antigen which is present on the cell wall of the bacteria is the “O” antigen, the antigen which is present on the flagellum is the “H” antigen and the antigen which is found on the capsule of the bacteria is the “K” antigen. These antigens have great variability with each of them existing in many different forms. This is the reason that E. coli exists in many different forms. This bacteria has been associated with many pathological conditions which include the inflammation of the gall bladder, inflammation of the biliary tract, infections of the urinary tract and the blood as well as diarrhea particularly traveler’s diarrhea. The newborns are also affected by it and present with inflammation of the meninges. Though this inflammation has also been reported in adults but it is more common in new born children and it usually occurs in adults as a result of invasive procedures. The respiratory tract might also be involved with resultant pneumonia. Epidemiology: This bacterium is responsible for infections of the urinary tract in 50 percent women in the United States. This is because there is a greater disposition towards females of this infection owing to the increased hospital visits related to deliveries and their higher susceptibility during the child bearing period. But this pattern is different for the newborns in which the rate of the infection of the urinary tract is higher in male children than in females. E. coli is also listed as an infection which occurs in the hospital settings and has been associated with an average of 31 percent hospital acquired infections in the United States as well as a cause of diarrhea in 4 percent of the people. The meningeal inflammation that results due to E. coli should not be overlooked because it accounts for 8 percent of the deaths due to this condition and it can also result in pathological conditions of the nervous system. Pathogenesis: The diarrhea that occurs due to the E. coli is caused by four classes of this bacterium which function in different ways. The first one is the Enteropathogenic E. coli that affect usually infants below the age of two years and hence occurrences are mostly reported from maternity homes. This group of E.coli has the capability of binding to the cells of the intestine and destructs its microvillus which leads to diarrhea. The spread occurs through the consumption of water or via the food that infants consume. The next group of E. coli is Enterocytotoxigenic E. coli. This group is the major cause for traveler’s diarrhea in all age groups. It produces exotoxins which are known as heat labile and heat stable exotoxins. They have an effect on adenylate cyclase and guanylate cyclase respectively. These enzymes lead to a cascade of reactions which cause retention of fluid and electrolytes with the passage of the intestine. This is turn results in diarrhea. The cause for this infection is also via the dietary intake. The world health organization has reported that this group of E. coli accounts for a mortality rate which is very high that is 380,000 deaths and 210 million people suffer from this infection every year. Enteroinvasive E. coli as the name indicates is a strain of E. coli which takes over the cell and it also has the capability of moving ahead from one cell to another. It enters a cell by endocytosis and within the cell it replicates and starts spreading to other cells. Contaminated water, cheese and human contact are the ways of its spread. The patient presents with mucus or blood in stools, high body temperature and discomfort in the abdomen. This dysentery caused by enteroinvasive E. coli accounts for the mortality of 500,000 children in the developing nations of the world every year. The last group is the enterohemorrhagic E. coli. This strain of E. coli is responsible for the production of verotoxin which is an exotoxin. This produces toxigenic effects for the colonic cells. According to a report of the Centers for Disease Control and Prevention, each year 70,000 people are affected by this strain of E. coli. This strain spreads from the ingestion of beef that has not been cooked completely and properly. This toxin can lead to a halt in the formation of proteins by disrupting the RNA. This can lead to inflammation associated with bleeding in the colon. It can also result in a fatal condition which is known as hemolytic uremic syndrome. This condition occurs when the verotoxin enters the circulation of a person. The kidneys stop functioning and the patient has hemolytic anemia as well as thrombocytopenia. The blood vessels and the renal cells possess receptors to which the verotoxin can bind and hence lead to anemia and kidney failure. The platelets then bind to these damages cells which results in thrombocytopenia. E. coli can also spread into the blood and lead to septic shock in a person. This spread can also lead to a raised body temperature and hypotension. It can also lead to infections of the urinary tract which occur as a result of the spread of normal E. coli which are present in the intestine. This can lead to increased frequency of urination, pain at urination and blood or pus in the urine. The pili of E. coli bind to the cells of the urinary tract and lead to these infections. These infections can be restricted to the lower urinary tract and they also have the ability to move up towards the kidneys and lead to renal infection. The meningeal inflammation in the newborn occurs as a result of the presence of E. coli in the birth canal. Laboratory Diagnosis: E. coli can be easily cultured on the nutrient agar as well as the Mac Conkey agar and the Eosin methylene Blue agar. They provide with grey, bright pink and metallic sheen colonies on the agars respectively. The most feasible temperature for E. coli is 37 degrees. Treatment: The pathologic conditions that result due to E. coli are all dealt with different treatments according to the specific requirement. In a infection of the urinary tract which is not very complicated can be treated by keeping the patient on antibiotics particularly penicillin which should be administered orally for a time duration of just one day to as long as three days. In the case of the infection of blood by the bacteria injections of antibiotics which should be third generation. This includes a combination therapy of a cephalosporin with an aminoglycoside. In the case of meningeal inflammation in new born, penicillin along with a cephalosporin is the suitable treatment. A loperamide and symptomatic treatment which mainly focuses on providing the patient with fluids is mainly done in the diarrhea which occurs due to this bacterium. Prevention strategies: Vaccination for infections caused by E. coli does not exist but measures can be taken to prevent the occurrence of disease states associated with this bacterium. The water lines that are serving the purpose of supplying water that is used for consumption should be tested for the presence of bacteria. The presumptive coliform test is performed for checking the infiltration of water by feces and the coli levels according to this test should have a higher value tan 3 in a sample of 100 ml. the milk should also be examined and tests to check the presence of bacteria should be seen. In the hospital setting it should be made sure that those patients who are catheterized are given antibiotics prior to the process so that their chances of acquiring urinary tract infections are lowered. If patients who are on intravenous drugs or medications get infections again and again, these should also be removed. A person who gets traveler’s diarrhea should take medications like doxycycline in advance so that he cannot get infected. It should also be ensured that one is on a healthy diet which includes food that is properly cooked and water that is clean and these precautions should particularly be taken when travelling to areas where bacterial infections are common. References: Top of Form Kumar, Vinay, Abul K. Abbas, Nelson Fausto, Stanley L. Robbins, and Ramzi S. Cotran. Robbins and Cotran Pathologic Basis of Disease. Philadelphia: Elsevier Saunders, 2005. Top of Form Levinson, Warren. Review of Medical Microbiology and Immunology. New York: McGraw-Hill Medical, 2008. National Institute of Allergy and Infectious Diseases, E. Coli. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES: National Institutes of Health, 2009. http://www3.niaid.nih.gov/topics/ecoli/Understanding/overview.htm Rao, P.V. Ramana. Essentials of Microbiology. CBS Publisher, 2004. Tarun, Maddapa and Chi Hong U Go. Escherichia Coli Infections. eMedicine,2009. http://emedicine.medscape.com/article/217485-overview Bottom of Form Bottom of Form Read More