Prevalence and Numbers of Listeria monocytogenes in Various Ready-to-Eat Foods over a 5-Year Period in Estonia

The prevalence and numbers of Listeria monocytogenes in various categories of ready-to-eat (RTE) food products taken from retail outlets and food industries over a 5-year period are presented. A total of 30,016 RTE food samples were analyzed for L. monocytogenes prevalence, and 3.6% were found to be positive. The highest prevalence was found for RTE fish and fish products (11.6%), especially for lightly salted and cold-smoked fish products. The overall prevalence of L. monocytogenes in other food categories was low, within the range of 0 to 3.9%. In addition, 14,342 RTE food samples were analyzed to determine the numbers of L. monocytogenes. A food safety criterion of 100 CFU/g was exceeded for 0.3% of RTE food samples. Samples most often exceeding the legal safety limit were from the RTE salted and cold-smoked fish product categories. High prevalence, 28.6 and 26.5%, respectively, and high numbers of L. monocytogenes among salted fish and cold-smoked fish products indicate a risk of listeriosis, especially for susceptible risk groups. The results of the current study can be used at both the national and the international levels to update the perception of the L. monocytogenes risk deriving from RTE foods.