The incidence of Listeria monocytogenes in meat, poultry and seafood plants in the Nordic countries

During 1998/1999 a total of 36 surveys were carried out in six meat, five seafood and two poultry processing plants. A total of 2522 samples, including processing lines and environment, personnel, raw materials and products (raw or ready-to-eat, RTE), were analysed for the presence of Listeria monocytogenes. The environmental and personnel samples were taken after cleaning and after the process had been running for 2 h. Samples of food products were taken after every important step during processing and samples of poultry carcasses were taken immediately after production and after storage for 21 days. The overall incidence of L. monocytogenes in meat processing plants varied from 0% to 15.1%, in poultry plants from 20.6% to 24.1% and in seafood plants from 5.9% to 22.1%. In raw products the average incidence was 15.6% for meat, 22.2% for poultry and 39.0% for seafood products. The heating steps during the production of RTE products eliminated Listeria. On average, 2.3% of RTE meat and 4.8% of RTE seafood products were recontaminated with L. monocytogenes. In the seafood sector almost all Listeria positive samples also included L. monocytogenes (91.1% of the positive samples), whereas in the meat and poultry sectors other Listeria species (mainly L. innocua) dominated. In most plants, the implemented cleaning procedures were insufficient to eliminate Listeria. The results clearly indicated the problematic sites, which in most plants were conveyer belts and other transporting equipment, floors and drains, but also raw material in the meat industry, cutting boards in the poultry industry and cooking equipment in the seafood industry. In order to solve the problems observed in this study, there is a need for close co-operation between the suppliers of equipment and cleaning agents, the staff of cleaning companies and hygiene specialists from the food industry.