Nofima reports

Report 20/2013, English Summary

Heir, Even; Langsrud, Solveig

Publication details

Publisher: Nofima

Issue: 20/2013

Number of pages: 21

International Standard Numbers:
Printed: 978-82-8296-083-0

Open Access: green


The goal of this work package has been to identify sources and transmission routes of Listeria in the Norwegian salmon industry. Systematic sampling at four processing plants was performed to determine L. monocytogenes incidence and sources in the production process from raw material to finished product (gutted / smoked salmon). Genetic typing of all isolated L. monocytogenes provided information about sources and transmission routes of L. monocytogenes in the plants. The results show that Listeria is routinely isolated from sites of processing environments and equipment, also after sanitation. The typing indicated that each processing plant holds persistent strains (“house strains”). There was no evidence of L. monocytogenes from round salmon / trout before processing. The fish are contaminated during processing from round fish to finished product. Manufacturing practices, routines and factors that should be focused for achieving increased Listeria control in the salmon industry were identified. The task is complex and requires focused effort throughout the production chain. The results of the report will form the basis for evaluation and testing of measures and the preparation of guidelines for management and prevention of Listeria in the salmon industry.