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. 2008 Apr;39(2):375-83.
doi: 10.1590/S1517-838220080002000032. Epub 2008 Jun 1.

Epidemiological Survey of Listeria monocytogenes in a gravlax salmon processing line

C D Cruz  1 , F A Silvestre, E M Kinoshita, M Landgraf, B D G M Franco, M T Destro
Affiliations

Epidemiological Survey of Listeria monocytogenes in a gravlax salmon processing line

C D Cruz et al. Braz J Microbiol. 2008 Apr.

Abstract

Listeria monocytogenes is a cause of concern to food industries, mainly for those producing ready-to-eat (RTE) products. This microorganism can survive processing steps such as curing and cold smoking and is capable of growing under refrigeration temperatures. Its presence in RTE fish products with extended shelf life may be a risk to the susceptible population. One example of such a product is gravlax salmon; a refrigerated fish product not exposed to listericidal processes and was the subject of this study. In order to evaluate the incidence and dissemination of L. monocytogenes 415 samples were collected at different steps of a gravlax salmon processing line in São Paulo state, Brazil. L. monocytogenes was confirmed in salmon samples (41%), food contact surfaces (32%), non-food contact surfaces (43%) and of food handlers' samples (34%), but could not be detected in any ingredient. 179 L. monocytogenes isolates randomly selected were serogrouped and typed by PFGE. Most of L. monocytogenes strains belonged to serogroup 1 (73%). 61 combined pulsotypes were found and a dendrogram identified six clusters: most of the strains (120) belonged to cluster A. It was suggested that strains arriving into the plant via raw material could establish themselves in the processing environment contaminating the final product. The wide dissemination of L. monocytogenes in this plant indicates that a great effort has to be taken to eliminate the microorganism from these premises, even though it was not observed multiplication of the microorganism in the final product stored at 4°C up to 90 days.

Keywords: Listeria monocytogenes; PFGE; gravlax salmon.

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Figures

Figure 1
Figure 1
Dendrogram showing the relationship among PFGE-tested isolates (179) using ApaI and AscI. See Table 1 for identification of the strains belonging to each profile.
Figure 2
Figure 2
Mean population of L. monocytogenes in vacuum package gravlax salmon stored at 4°C for 90 days.
See this image and copyright information in PMC

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