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Application of multilocus enzyme electrophoresis in studies of the epidemiology of Listeria monocytogenes in Denmark.

https://arctichealth.org/en/permalink/ahliterature220463
Source
Appl Environ Microbiol. 1993 Sep;59(9):2817-22
Publication Type
Article
Date
Sep-1993
Author
B. Nørrung
N. Skovgaard
Author Affiliation
Department of Veterinary Microbiology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Source
Appl Environ Microbiol. 1993 Sep;59(9):2817-22
Date
Sep-1993
Language
English
Publication Type
Article
Keywords
Animals
Cattle
Denmark - epidemiology
Electrophoresis, Starch Gel
Enzymes - genetics - isolation & purification
Fishes
Food Microbiology
Genetic Variation
Humans
Listeria monocytogenes - classification - enzymology - genetics
Listeriosis - epidemiology - microbiology
Sheep
Abstract
A total of 245 strains of Listeria monocytogenes were investigated. These strains were isolated from human and animal cases of listeriosis as well as from different kinds of raw and processed foods. Thirty-three electrophoretic types (ETs) were identified among the 245 strains. The strains investigated included all human clinical strains isolated in Denmark during 1989 and 1990. Seventy-three percent of the strains isolated in this period were assigned to one of only two ETs (ET 1 and ET 4). ET 1, which was found to be the most frequently occurring ET among strains isolated from human clinical cases, was also found to occur rather frequently in animal clinical cases. ET 1 was, however, found only sporadically among strains isolated from foods and food factories. The data indicate that there might be something distinctive about the physiology or ecology of the ET 1 clone which makes it more likely to bring about disease in human beings either because of high pathogenicity or because of a special ability to multiply to infectious doses in processed foods. Another type, designated ET 4, was found to be the next most frequently occurring ET, after ET 1, among human clinical isolates. This could be explained by the fact that ET 4 was found to be the most frequently occurring ET within food isolates.
Notes
Cites: Acta Pathol Microbiol Scand B Microbiol Immunol. 1972;Suppl 229:1-1574624477
Cites: N Engl J Med. 1983 Jan 27;308(4):203-66401354
Cites: Appl Environ Microbiol. 1986 May;51(5):873-842425735
Cites: J Appl Bacteriol. 1987 Jul;63(1):1-113115937
Cites: Proc Natl Acad Sci U S A. 1989 May;86(10):3818-222498876
Cites: Int J Food Microbiol. 1992 Jan-Feb;15(1-2):51-91622759
Cites: Appl Environ Microbiol. 1990 Jul;56(7):2133-412117880
Cites: Int J Food Microbiol. 1988 May;6(3):229-423152796
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Cites: Appl Environ Microbiol. 1991 Jun;57(6):1624-91908204
Cites: J Infect. 1990 May;20(3):251-92341735
PubMed ID
8215357 View in PubMed
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Characterisation of Danish isolates of Listeria monocytogenes by multilocus enzyme electrophoresis.

https://arctichealth.org/en/permalink/ahliterature224603
Source
Int J Food Microbiol. 1992 Jan-Feb;15(1-2):51-9
Publication Type
Article
Author
B. Nørrung
Author Affiliation
Institute of Veterinary Microbiology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Source
Int J Food Microbiol. 1992 Jan-Feb;15(1-2):51-9
Language
English
Publication Type
Article
Keywords
Alleles
Animals
Bacteriophage Typing
Cluster analysis
Denmark - epidemiology
Electrophoresis, Starch Gel
Enzymes - analysis - genetics
Food Microbiology
Genetic Variation
Humans
Listeria monocytogenes - classification - enzymology - genetics
Listeriosis - epidemiology - microbiology
Meat - microbiology
Milk - microbiology
Serotyping
Sewage
Abstract
A total of 84 strains of Listeria monocytogenes were analysed by multilocus enzyme electrophoresis at twelve enzyme loci. Eight enzyme loci were polymorphic with between 2 and 4 alleles per locus. Fourteen electrophoretic types (ETs) were identified. Among 62 human clinical isolates from Denmark, 8 different ETs were defined. Two ETs, designated ET 1 and ET 6, accounted for 77% of the human clinical isolates investigated. These ETs are identical with those responsible for several epidemics in Switzerland and in the United States. Comparison of 58 isolates of L. monocytogenes, typed by MEE, in relation to phage typing showed that phage typing was more discriminatory than MEE. The ability of MEE to distinguish between phage types of Epi-type and other phage types, however, was almost optimal. MEE typed 23 of 24 strains of Epi-type as belonging to ET 1. In contrast ET 1 was not found in 26 strains with phage types other than the Epi-type.
PubMed ID
1622759 View in PubMed
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Incidence and control of Listeria monocytogenes in foods in Denmark.

https://arctichealth.org/en/permalink/ahliterature51662
Source
Int J Food Microbiol. 1999 Dec 15;53(2-3):195-203
Publication Type
Article
Date
Dec-15-1999
Author
B. Nørrung
J K Andersen
J. Schlundt
Author Affiliation
Division of Microbiological Safety, Institute of Food Safety and Toxicology, Danish Veterinary and Food Admnistration, Søborg. bin@vfd.dk
Source
Int J Food Microbiol. 1999 Dec 15;53(2-3):195-203
Date
Dec-15-1999
Language
English
Publication Type
Article
Keywords
Animals
Denmark - epidemiology
Fish Products - microbiology - standards
Food Microbiology
Food Packaging
Food-Processing Industry
Incidence
Listeria Infections - epidemiology
Listeria monocytogenes - growth & development
Meat Products - microbiology - standards
Public Policy
Vegetables - microbiology - standards
Abstract
The Danish regulatory policy on Listeria monocytogenes in foods is based on the principles of HACCP and was developed using a health risk assessment approach. The Danish policy focuses examinations and criteria for L. monocytogenes in ready-to-eat foods and is based on a combination of inspection and product-testing. Based on current epidemiological information from several countries, a concentration of L. monocytogenes not exceeding 100 cfu/g of food at the time of consumption, seems to be of low risk to the consumers. In Denmark, ready-to-eat foods have been placed into six categories where absence of L. monocytogenes in 25 g is required in foods heat treated in the final package and in heat-treated as well as preserved, non heat-treated foods which can support growth within the shelf life. This level is necessary in foods capable of supporting growth, in order not to exceed 100 L. monocytogenes per g at the point of consumption. In heat-treated and preserved foods, which are not supportive of growth within the shelf-life and for raw, ready to eat foods, a level below 10 L. monocytogenes per g is regarded acceptable. A level between 10 and 100 L. monocytogenes per g is not satisfactory and a level above 100/g is not acceptable. Data on the qualitative and quantitative occurrence of L. monocytogenes in foods in Denmark are presented and discussed. In 1997 and 1998, greater than 15,000 samples from different categories of food were examined (semi-quantitatively) for the presence of L. monocytogenes. A significant difference could be seen in the number of samples containing more than 100 L. monocytogenes per g, between different categories of foods (1997, P = 0.001; 1998, P = 0.016). In 1997, preserved meat products and preserved fish products and to a lesser extent vegetables and meat or vegetable mayonnaise were more likely to contain high numbers (i.e. above 100 cfu/g) of L. monocytogenes than other food categories. In 1998, preserved meat products, but also heat-treated meat products, vegetables and meat or vegetable mayonnaise had the highest frequency of samples with > 100 L. monocytogenes per g. In a survey performed in 1994 and 1995, 1.3% of ready-to-eat food samples (heat-treated meat products, preserved meat and fish products) were found to be contaminated with L. monocytogenes at a level above 100 cfu/g. The samples included in this survey were primarily products produced by authorized companies and were comprised mainly of vacuum packed products or products packed in modified atmosphere and with long shelf lives, typically above several weeks. The corresponding percentages of positive samples primarily processed in the retail outlets (heat-treated meat products, preserved meat and fish products) in 1997 and 1998 were 0.3% and 0.6%, respectively. The results suggest that ready-to-eat meat and fish products with extended shelf-lives produced by authorized companies are more likely to contain high numbers (> 100 cfu/g) of L. monocytogenes than products processed in the retail sector which often have a shorter shelf life.
PubMed ID
10634710 View in PubMed
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