Contents
Introduction
History
Characteristics
Mechanism of action
Factors affects growth
Toxins
Symptoms
Transmission
Complications
Outbreaks
Food Association
Diagnosis
Disinfetants
Trearment
Vaccination
Preventions
References
Enterohemorrhagic Escherichia coli
Introduction
E.coli is a gram negative bacteria present in the form of rods(bacillus) in the Enterobacteriaceae. Mostly E.coli are normal commensals of intestines so that isolation of pathogenic strains on the basis of Virulence factors e.g toxins. EHEC group produces shiga-like toxins (stx), enterohemolysin, and intimate adhesion factor (Intimin).
Serotypes
E.coli serotypes based on the antigens as O (somatic polysaccharides), H (flagellar) and K (capsular). EHEC serotypes comprises of E.coli O157:H7 and others O26, O103, O111, O145. Resarch studies shows only small no. of E.coli are enough to cause infection as 10-100 microbes.
History of EHEC
In 1982,E.coli O157:H7 was first identified to cause bloody diarrhea by eating undercooked or contaminated raw hamburger.
Infection was first recognized by CDC separates two outbreaks in Oregon and Michigan by eating hamburger at National chain restaurants.
Patients experienced hemorrhagic colitis (Inflammation and bleeding of colon) due to E.coli O157:H7 referred as hamburger disease.
Characteristics
• E.coli O157:H7 is a principal serotype associated with hemorrhagic colitis
• It does not ferment sorbitol and have glucuronidase activity when comparing with other E.coli strains.
• It grows rapidly at 30-42°C, poor growth at 44-45°C, and shows no growth at 10°C.
• It is resistant to pH 4.5...
... middle of paper ...
...., and Ammar, M.S.1993. Survival and growth of Escherichia coli O157:H7 on salad vegetables. Appl. Environ. Microbiol.59:1999–2006.
Ahmed, N.M., Conner, D.E., and Huffman, D.L. 1995.Heat-resistance of Escherichia coliO157:H7 in meatand poultry as affected by product composition. J.Food Sci.60: 606–610.
Doyle, M.P., Escherichia coli 0157:H7 and its significance in foods, lilt. J. Food Microbiol., 12,289,1991.
Donnenberg, M.S. and Whittarn, T.S., Pathogenesis and evolution of virulence in enteropathogenic and enterohemorrhagic Escherichia coli, J. Clin. lnv., 107(5),539, 200l.
Anonymous, FSIS background of Escherichia coli update: E. coli 0157:H7, Media Relation Office,Food Service and Inspection Service, USDA, January 1993.
FUNDAMENTAL
FOOD MICROBIOLOGY FOURTH EDITION
The isolate possesses some enzymes required for hydrolytic reactions. Hydrolytic enzymes found to be secreted from the bacterium, are -amylase, casein, and PYRase. In the starch hydrolysis and casein tests, there was a zone of clearing around the bacterium, which was indicative of the secreted enzymes necessary to break down starch and casein. In the PYR test, the presence of PYRase was detected by a color change to red on the PYR disc after the addition of the PYR reagent (p-dimethylaminocinnamaldehyde). Hydrolytic enzymes for which the EI tested negative were urease, gelatinase, and DNAse. In the Urea Hydrolysis test, it was observed that the urea broth did not have a color change, indicating that there was no urease secreted to break down urea in the broth. Similarly, there was no gelatinase present to break down gelatin in the Gelatin Hydrolysis test, so the nutrient gelatin remained solid. It was concluded that the EI does not possess DNase because there was no clearing zone around the bacteria, indicating that DNA had not been
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
ABSTRACT: Water samples from local ponds and lakes and snow runoff were collected and tested for coliform as well as Escherichia coli. Humans as well as animals come into contact with these areas, some are used for recreational activities such as swimming and some are a source of drinking water for both animals and humans The main goal of this experiment was to see which lakes, snow run off and ponds tested positive for coliform or Escherichia coli and to come up with some reasoning as to why. It was found that the more remote pond with less contact contained the most Escherichia coli. However, another lake that many swim in and use as their drinking water indeed tested positive for a small amount of Escherichia coli. The two samples from the snow showed negative results for both coliform and Escherichia coli and the two more public ponds that aren’t as commonly used as a source of human drinking water but animal drinking water tested in the higher range for coliforms but in the little to no Escherichia coli range. It was concluded that the remote pond should be avoided as it’s not a safe source of drinking water for humans or animals. Other than that, the the other ponds are likely to be safe from Escherichia coli, but coliforms are a risk factor.
Nestle, Marion. Safe Food: Bacteria, Biotechnology, and Bioterrorism. Berkeley, CA: University of California Press, 2003.
The purpose of this investigation was to identify an unknown bacterium. “At any time there are millions of bacteria living around, on, or inside us” (The Plague). Bacterium can’t be identified by merely looking at it. Many bacteria have the similar appearances in growth. “In most cases, detection is based on the reaction of an enzyme with a certain substrate” (Sigma-Aldrich). Identification is usually based on the results of the bacterium’s cells metabolic capacities.
E. coli are bacteria that can cause an infection in various parts of your body, including your intestines. E. coli bacteria normally live in the intestines of people and animals. Most types of E. coli do not cause infections, but some produce a poison (toxin) that can cause diarrhea. Depending on the toxin, this can cause mild or severe diarrhea.
Abstract: Salmonella is a bacterium that causes one of the most common intestinal infections in the United States - Salmonellosis. The chance of contracting this disease is significantly high, and more and more people are suffering from the symptoms and complications of Salmonella. This paper will discuss about the disease itself, the current outbreaks that are related to this disease, preventions and the treatments.
Salmonella is a gram-negative bacillus that causes inflammation of the GI tract and in some cases, if the immune response is not sufficiently powerful and treatment is not administered, can become systemic and cause even more serious conditions throughout the body. After ingestion, these bacteria cause infection by invading the epithelial cells of the small intestine and macrophages. Though there are more than two thousand different subspecies of Salmonella, few of them are able to cause serious conditions in humans—for most, the disease resolves itself in a matter of days. Those who are most affected by Salmonella infection are infants, the elderly, and people with compromised immune systems. Some of the main conditions caused by Salmonella are gastroenteritis, enteric fever, and bacteremia, while the general symptoms of salmonella include vomiting, nausea, diarrhea, and abdominal pain. While there are typically few to no long-term effects as a result of a Salmonella infection, more serious complications may arise.
In 1997, approximately 35 million pounds of ground beef was recalled by Hudson Foods because a strain of E. Coli was found in the food. However, by the time the beef was recalled, 25 million pounds had already been eaten. Schlosser notes that the nature of food poisoning is changing. Prior to the rise of large meatpacking plants, people would become ill from bad food in small, localized arenas. Now, because meat is distributed all over the nation, an outbreak of food poisoning in one town may indicate a nationwide epidemic.
“Salmonella Questions and Answers.” USDA Food Safety and Inspection Service. 20 Sept. 2006. 20 July 2008 .
Talaro , K., & Chess, B. (2012). Foundations in microbiology. (8th ed., pp. 563-564). New York, NY:
E. Coli and other foodborne illnesses are something that should be of major concern to everybody, becasue nobody is safe from it. It is not something that can be prevented or
E. Coli 0157, written by Mary Heersink, is a nerve-racking, adrenaline-filled story of a mother's experience with a then unknown deadly bacteria. The book brings up many reactions in its readers, especially the questioning of the practice of doctors in hospitals. The reader's knowledge base of scientific procedures in emergency centers was widened as well as the knowledge of how to the human body reacts to different agents in its system.
Enterococcus faecalis is a genus of gram positive cocci and form short chains or are arranged in pairs. They are nonmotile, facultative anaerobic organisms and can survive in harsh conditions in nature. There are over 15 species of the Enterococcus genus but about 90% of clinical isolates are E. faecalis. E. faecalis is a nosocomial pathogen because it is commonly found in the hospital environment and can cause life-threatening infections in humans. It is a bacterium that normally inhabits the intestinal tract in humans and animals but when found in other body locations it can cause serious infections. The most common sites for E. faecalis infections are the heart, bloodstream, urinary tract, and skin wounds. Due to vancomycin-resistant Enterococci, many antibiotics have been shown ineffective in the treatment. In this paper, I will describe the ecology and pathology of E. faecalis; the antibacterial resistance; treatment; and, what you can do to prevent Enterococcus infection.
Campylobacter is a bacterial pathogen that causes fever, diarrhea, and abdominal cramps. It is the commonly identified bacterial cause of diarrhea illness in the world. These bacteria live in the intestines of birds, and most raw poultry meat has the bacteria in it. Eating undercooked chicken or other food that has been contaminated with the juices dripping from raw chicken is the most frequent source of this particular infection.