Laboratory Techniques for the Microbial Analysis of Food - Lab Report Example

Pathogenic Escherichia coli report] By   Insert   Presented to Location Due Escherichia coli 0157:H7 was recognized as a pathogen in 1982 during an investigation of an outbreak hemorrhagic colitis (Remis, 1983, 1).Infections caused by Escherichia coli O157:H7 and other verocytotoxigenic E. coli (VTEC) have become a major public concern in Europe and other parts of the world. Escherichia coli O157 can lead to severe life threatening illnesses even though absolute numbers are low when compared with other enteric pathogens like campylobacter or salmonella. An estimation of 46, 480 illnesses occur due to Escherichia coli 0157 infection each year leading to a projected 2,168 hospitalizations and 61 deaths per annum. Due to this many Nations in Europe have taken rapid response in expanding the knowledge about these organisms and the diseases which they cause. This will help people to guard themselves from coming to contact with the hazard they bring. Escherichia coli reside in the gastrointestinal territory of humans and other animals. This bacterial the Escherichia coli stay alive in several pathogenic forms that ground a variety of human diseases. Most of the Escherichia coli bacteria’s are harmless but Escherichia coli 0157:h7 causes severe diarrhea and kidney damage. Escherichia coli 0157:H7 can infect anyone at any age but the most vulnerable are the children and the elderly who can develop very serious complications. Infection of the Escherichia coli 0157 can lead to (HUS) Hemolytic uremic syndrome that is characterized by hemolytic anemia, thrombocytopenia, and renal injury (Remis, 1983, 3). Enteropathogenic Escherichia coli (EPEC) sticks on to the intestinal mucosa and tissue culture cells in the distinctive fashion, destroying microvillus, changing the cytoskeleton and put together intimately to the host cell covering in a manner termed the attaching and destroying effect. Enteropathogenic Escherichia coli (EPEC) forms three dimensional micro colonies in a pattern known as localized adherence. Recent studies have changed or improved our understanding on the effect of these pathogens to the host after infection occurs. The type III-mediated secretion of bacteria proteins is required in the intimate attachment in which several are moved directly into the contaminated cells, including the own receptor of the bacteria. Fastening to this membrane-bound, Enteropathogenic Escherichia coli (EPEC) is allowed to intimately attach to mammalian cells by the pathogen-derived protein. Translocation of the Enteropathogenic Escherichia coli (EPEC) activates signaling pathways within the underlying cell, leading to a restructuring of the host acting cytoskeleton and the configuration of pedestal like structures underneath the supporter bacteria. There is also an interaction between Enteropathogenic Escherichia coli (EPEC) and host cells that has been described including that of between intimin and cellular receptors and those involving a bundle forming pilus and flagella. Symptoms that one is infected with Escherichia coli 0157:H7 bacteria are sometimes hard to notice. One can easily spread the bacteria to others without knowing. It is hard to recognize these symptoms because they are very similar to other diseases caused by other bacteria therefore making the diagnosis of Escherichia coli 0157:H7 infection complicated. The symptoms of this bacterial infection usually end within a week and other problems cannot be noticed. Two weeks after the start of diarrhea rigorous blood and kidney troubles may occur which can cause kidney failure that can lead to death of the patient. The most common symptoms are severe stomach upset and stomach tenderness, diarrhea which is watery at first then becomes bloody accompanied with nausea and vomiting especially after meals. Escherichia coli O157 outbreaks by year, 1986–2000 In most parts of Europe the outbreak of waterborne Escherichia coli O157:H7 occurred around august 1999. Culture methods were first used to isolate Escherichia coli O157:H7 from specimens from about 1000 patients who had developed symptoms like diarrheal illness. molecular detection of stx1 and stx2 Shiga toxin genes, immunomagnetic separation, and selective culture enrichment were utilized to detect and isolate Escherichia coli O157:H7 from an unchlorinated well and its distribution points. Tests to identify isolates as Escherichia coli have been simple tests perfomed predominantly to differenciate them from organuisms normally associated with uncontaminated water. Escherichia coli are described as “coliform” since full biochemical analyses are not generally perfomed. Regulations have been put in place all over the world defining the standards for water based on “coliform count” . a good example is the US, the regulations published in the federal registrar (1986), it is required that there be zero coliforms per 100ml in drinking water. To distinguish other related species that can be found in the natural environment from Escherichia coli, Indole, Methyl red, Voges-proskauer and Citrate (IMViC) reactions which is a battery test was developed in order to differentiate fecal coliforms from nonfecal coliforms. This set of test examines a range of factors, they are: I. The ability of an organism to produce indole. II. The ability of an organism to produce sufficient acid to change the color of Methyl red indicator, III. The ability of an organism to generate acetoin, an intermediary in the butanediol fermentation alleyway. IV. The ability of an organism to grow on citrate as the sole source of carbon. In the first two tests Escherichia coli is positive while it is negative in the other two tests. For the nonfecal coliforms the results are the opposite where they are negative in the first two and negative in the other two. Positive result of Escherichia coli in water indicates pollution of fecal. Escherichia coli strain is usually harmless non pathogen. Salmonella and shigella are pathogenic coliforms that can be readily distinguished from strains of Escherichia coli on the basis of a lactose fermentation test. Almost all strains of Escherichia coli ferment the sugar lactose while those of salmonella and shigella do not ferment lactose. There are sets of standards techniques that have been adopted so that detection on Escherichia coli in foods can be easy. These standards are accepted by the International Standards Organization (ISO, 1984). These standards were set by the International Commission on Microbiological Specifications for Foods (ICMSF, 1978). The method they use requires the use of laurly sulfate tryptose broth at 35 or 37¢XC as a mild selective enrichment medium. This is trailed by growth in EC broth containing 0.15% bile salts at 45¢XC as a second discriminating step. The ability to produce indole from tryptophan (in tryptone broth) at 45¢XC defines the strains as Escherichia coli. These experiments miss some types of Escherichia coli, such as those most closely related to the Shigella group, but it is the recognition of achievable fecal contamination that is important in these tests rather than the presence of specific types. All over the word there is no specific method of detecting Escherichia coli in water. The most common method in Europe is using membrane filter enumeration for both total and thermo tolerant coliforms. Another test that can be performed is IMViC tests on selected isolates. High standard of food and personal hygiene are required to prevent Escherichia coli infection and outbreaks. Preventive measures for Escherichia coli o157:H7 are the same as those of other food bone diseases so it is easy to avoid it. These precautions should be taken seriously for one’s own safety. One of these interventions is that all ground beef and hamburger should be thoroughly cooked. This is because ground beef can turn brown before all diseases causing bacteria are killed. A digital instant read thermometer should be used to ensure thorough cooking. The beef should cook until the thermometer reads 160 degrees F. another important intervention is that one should only drink pasteurized milk or juice. These pasteurized drinks do not contain these Escherichia coli pathogens. Fruits and vegetables should be washed thoroughly especially those that will be eaten row. In the house one should ensure that they practice regular hand washing before food preparation and consumption and after toilet contact. Those who have a weak immune system and pregnant women have special recommendations from world health organization (WHO). They should not eat hot dogs, plates, luncheon meats, bologna or other delicatessen meats unless they are reheated until steaming hot. Spilling of raw meat fluids on other foods and preparation surfaces should be avoided. They should also not eat pre prepared salads like ham salads, chicken salads or even seafood salads. Pregnant women should not eat refrigerated meat spreads but they can take canned or shelf stable products. If the infection of Escherichia coli is realized the spread should be dealt with as soon as possible to avoid a crisis. People with diarrhea and vomiting should be cautious to keep away from spreading infection to friends and family. If one notices the symptoms of Escherichia coli infection they should seek medical attention as soon as possible so as to get required treatment before it gets worse. The high frequency of outbreaks of Escherichia coli 0157:H7, CDC recommended that all patients being screened from community acquired diarrhea infections have their stool samples analyzed with antisera for Shinga toxin. Escherichia coli 0157:H7 can be transmitted from one person to another, usually by direct physical contact. Escherichia coli 0157:H7 is commonly found in companies have developed a vaccine to reduce the number of these bacteria in cattle. There is no available vaccine for Escherichia coli 0157:H7 in humans. Reference list Acheson D.W, 2013, patient information food poisoning(food borne illness). Available at www.uptodate.com. [17 Feb 2014] Cody S.H, Glynn M.K, Farrar J.A, Cairns K.L, Griffin P.M, 1999. An outbreak of Escherichia coli O157:H7 infection from unpasteurized commercial apple juice. Ann Intern Med. Colia J.E, 1998, Clinical, microbiological and epidemiological aspects of Escherichia coli O157 infection. Available at: onlinelibraray.wiley.com [17 Feb 2014]. Davis C.P, 2012, E. COLI 0157:H7. Available at: www.medicinenet.com [17 February 2014] Kipper L.D, 2012, NIH E. coli prevention. Available at http://www.niaid.nih.gov/topics/ecoli/understanding/pages/prevention.aspx [17 Feb 2014]. Riley L.W, Remis R.S, Helgerson S.D, McGee H.B, Wells J.G, Davis B.R, 1983. Hemorrhagic colitis associated with a rare Escherichia coli serotype. N Engl J Med. Read More