Survey of Listeria monocytogenes in ready-to-eat products: Prevalence by brands and retail establishments for exposure assessment of listeriosis in Northern Spain

The prevalence of Listeria monocytogenes in ready-to-eat products of markets in Northern Spain was studied, being analyzed 783 samples of deli meat products, smoked fish and pâté. RTE smoked fish was the most frequently contaminated food category (25% positive), with high occurrence in some brands (60% of lots positive). Significant differences in prevalence were found in in-store-packaged deli meat products (8.5%) with respect to manufacturer vacuum-packaged presentation (2.7%). Serological and molecular characterization of L. monocytogenes isolates confirmed the persistence of several clusters within manufacturing environments, as the same pulsotype was repeatedly isolated from different lots of the same brand and from different sliced products of the same store. These results reflect the need to improve hygiene and disinfection programs by addressing more accurate cleaning practices and continuous education of food workers.