Prevalence and concentration of Listeria monocytogenes in sliced ready-to-eat meat products in the Hellenic retail market

The aim of this work was to estimate the prevalence and concentration of Listeria monocytogenes in packaged precut (slices or cubes) ready-to-eat (RTE) meat products available in the Hellenic retail market. Samples of these RTE meat products (n = 209) were taken from local supermarkets during a 3-month period and analyzed for the presence of L. monocytogenes with an automated enzymatic qualitative immunoassay followed by biochemical confirmation of positive results. The concentration of the pathogen in the positive samples was also determined. Seventeen samples (8.1%) were positive for L. monocytogenes. Eight (47.1%) of these 17 samples were from the same manufacturer; 36.4% of the products tested from this manufacturer were positive for L. monocytogenes. When bacon samples were not considered, the estimated prevalence of L. monocytogenes in sliced RTE meat products was much lower (3.1%). The L. monocytogenes populations in all positive samples were low, < or = 10 CFU/g. In 64.7% of the L. monocytogenes-positive samples, other Listeria species, including L. innocua and L. welshimeri, were also present at <10 to 690 CFU/g. These results indicate that L. monocytogenes is present in low numbers but is in a considerable proportion of the packaged precut RTE meat products that are sold in the Hellenic retail market. Cooked ham and bacon cut in cubes were the sample types most often contaminated with L. monocytogenes. The higher level of handling (e.g., cutting) associated with these products may further increase the risk of contamination with L. monocytogenes.