Notes - Listeria Monocytogenes

Notes - Listeria Monocytogenes - LISTERIA MONOCYTOGENES...

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LISTERIA MONOCYTOGENES Listeriosis has emerged as one of the major foodborne diseases during the last decade. Listeriosis is an atypical foodborne disease of major public health concern because of the severity and non-enteric nature of the disease (meningitis, septicemia and abortion), a high case fatality rate, long incubation time, and risk groups when infected leads to T-cell-mediated immunity. Listeria: Characteristics of the organism Within the genus of Listeria, only L. monocytogenes and L. ivanovii are considered virulent. L. monocytogenes has 13 serovars which can cause disease but 95% of human isolated belong to 3 serovars: 1/2a,1/2b, and 4b. Serovar 4b strains are responsible for 33 to 50% of sporadic human cases worldwide and for all major food outbreaks since 1981. Isolates recovered from food mostly belong to 1/2a and 1/2c serogroup. Tolerance and Susceptibility to Preservation Methods Pasteurization is a safe process which reduces L. monocytogenes in raw milk to levels that do not pose a risk to human health. Organic acids can inhibit Listeria and it can not grow below a pH of 4.5. It can survive high levels of salt (30%), nitrite levels approved for food, and repeated freezing and storage at -18 C.
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This note was uploaded on 09/25/2010 for the course FOS 4222 taught by Professor Rodrick during the Spring '08 term at University of Florida.

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Notes - Listeria Monocytogenes - LISTERIA MONOCYTOGENES...

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