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Peiris, Inoka, 2005. Listeria monocytogenes, a food-borne pathogen. Second cycle, A1N, A1F or AXX ( AXX). Uppsala: SLU, Dept. of Biomedical Sciences and Veterinary Public Health



Listeria monocytogenes is a Gram positive, aerobic, facultative anaerobic and nonacid fast bacterium, which can cause the disease listeriosis in both human and animals. It is widely distributed thoroughout the environment and has been isolated from various plant and animal food products associated with listeriosis outbreaks.

Contaminated ready-to-eat food products such as gravad and cold-smoked salmon and rainbow trout have been associated with human listeriosis in Sweden. The aim of this study was to analyse the occurrence and level of L. monocytogenes in
gravad and cold-smoked salmon (Salmo salar) products packed under vacuum or modified atmosphere from retail outlets in Sweden. Isolated strains were characterized by serotyping and the diversity of the strains within and between
producers were determined with PFGE (Pulsed-field gel electrophoresis). The characterized fish isolates were compared with previously characterized human strains.
L. monocytogenes was isolated from 11 (three manufacturers) of 56 products analysed. This included gravad salmon products from three manufacturers and cold-smoked salmon from one manufacturer. The highest level of L. monocytogenes found was 1500 cfu/g from a cold-smoked salmon product but the level was low (<100 cfu/g) in most of the products. Serovar 1/2a was predominant,
followed by 4b. Three products of gravad salmon harboured more than one serovar. PFGE typing of the 56 salmon isolates detected five Asc I types: four types were identical to human clinical strains with Asc I and one was identical and one was closely related to human clinical strains with Apa I. Isolation of identical or closely related L. monocytogenes strains from human clinical cases of listeriosis and gravad and cold-smoked salmon suggested that these kinds of products are possible sources of listeriosis in Sweden. Therefore, these products should be considered risk products for human listeriosis.

Main title:Listeria monocytogenes, a food-borne pathogen
Authors:Peiris, Inoka
Series:Report / International Master of Science Programme, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences
Volume/Sequential designation:50
Year of Publication:2005
Level and depth descriptor:Second cycle, A1N, A1F or AXX
Student's programme affiliation:MSCVE Master of Science Programme in Veterinary Medicine 90 HEC
Supervising department:(VH) > Dept. of Biomedical Sciences and Veterinary Public Health
Keywords:L. monocytogenes, gravad and cold-smoked salmo salar, food, PFGE
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Subject. Use of subject categories until 2023-04-30.:Food contamination and toxicology
Additional Information:Överförd från avhandlingsarkivet/Transferred from the Dissertations and Graduate Thesis Archive
Deposited On:21 Nov 2011 10:52
Metadata Last Modified:20 Apr 2012 14:23

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