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Case study - Outbreak of food poisoning at scientific conference.

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Case Study "Outbreak of food poisoning at scientific conference" In order to investigate the outbreaks described, the following table (table 1) was presented. The table concentrate at the critical points of the outbreak. The range of onset illness was generated in the table as the incubation period of unknown micro-organism. The duration of the reported symptoms from victims was generated as the duration of illness. The temperature at which the sample was held was generated in the table as environment. Table1. Critical points of the outbreak Outbreak title Outbreak of food poisoning at scientific conference Symptoms Abdominal pain, diarrhoea, fever, nausea, vomiting Incubation period 15-48 hours Duration of illness 3-7 days Likely source of the outbreak Cooked meats (ham, roast beef, chicken) Environment 24�C Examined samples Meats left over Laboratory findings Rod, Gram -ve, facultative anaerobe From the critical points given on the table 1, it could be assumed that the micro-organisms that could be involved in this outbreak were Salmonella enterica (S. enterica), Escherichia coli (E.coli) or Campylobacter jejuni (C. jejuni). These micro-organisms are very common cause of food poisoning and they have very similar properties. They are Gram -ve rods. ...read more.


The most Gram -ve rods are associated with the intestinal infections and they are oxidase negative and they do ferment glucose. These micro-organisms belong to the family of Enterobacteriaceae. From the catalase test it could be assumed that the micro-organism could be Salmonella, Klebsiella, Eschirichia or Enterobacter. These genera appeared to be catalase positive. With the help of catalase and biochemical tests the genus from the wanted micro-organism can be identified. Table 3 was given in order to calculate the generation time of organism Y at 24 �C and to describe an appropriate method for determining the number of aerobic organisms/g of food, explaining why the results are reported as colony forming units (CFU). Table 3 Log 10 number of colony forming units of aerobic organisms/g and the log 10 number of colony forming units Y organisms/g chicken in chicken held at room temperature (24 �C) for 6 hours. Time Hours Log10 total number colony forming units of aerobic organisms/g Log10 Total number of colony forming units Y/g chicken 0 3.68 2.83 1 3.65 3.40 2 4.45 3.87 3 4.85 4.24 4 5.47 4.97 5 5.92 5.51 6 6.31 5.98 The generation time or doubling time is the time taken for the bacteria to double. ...read more.


Cooked products have to be cooled and reheat quickly. This will prevent the formation of vegetative cells. Spores are found in many products such as vegetables, meats, chicken etc. They are released from vegetative cells and can survive very high and low temperatures. When food is left for a long time at room temperature, this would lead the spores to revert to a vegetative cell. Vegetative cells are bacteria which can lead to an outbreak. Reference: 1. Tortora G. J., Funke B. R., Case C. L. (1992). Microbiology, An Introduction. Fourth Edition. The Benjamin/Cummings Publishing Company, Inc. 2. Van Denmark P. G., Batzing B.,L. (1987). The Microbes. An Introduction to their nature and importance. The Benjamin/Cummings Publishing Company, Inc. 3. Madigan M. T., Martinko J. M. and Parker J. (2003). Brock Biology of Microorganisms. Tenth Edition. Pentice Hall. 4. Postage J.(1992). Microbes and Man. Third Edition. Blackwell. 5. Brooks G. F., Butel J. S. and Morse S.A. (2004). Jawetz, Melnick and Adelberg;s Medical Microbiology. Twenty third Edition. Lange Medical Books/McGraw-Hill 6. Gwendolyn, Burton R.W. and Engelkirk P.G. (2000). Microbiology for the Health Sciences. Sixth Edition. Lipponcott Williams and Wilkins 7. Seeley Jr H., W., Van Denmark P., J., Lee J. L. (1991). Microbes in Action. A Laboratory Manual of Microbiology. Fourth Edition. Freeman. 8. BMS 3521. Medical Microbiology. Handouts. 9. BIO 3525. Microbiology. Handouts. 10. http://trishul.sci.gu.edu.au/courses/ss12bmi/micro_groups/fac_anaerobes.html 11. http://www.patient.co.uk/showdoc/40000349/ 12. http://www.hpa.org.uk/infections/topics_az/salmonella/se_update.html 13. http://itech.pjc.edu/fduncan/mcb1000/IdGNBChart.pdf ...read more.

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