Intensive environmental surveillance plan for Listeria monocytogenes in food processing plants and retail stores of Central Italy: prevalence and genetic diversity.

Following a severe listeriosis outbreak occurred in Marche Region (Central Italy) between 2015 and 2016, an intensive environmental monitoring plan was performed in the affected area involving both meat-producing plants and retail grocery stores. Longitudinal follow-up sampling was conducted where positive samples were found, after cleaning and sanitation to verify their effectiveness. The aim of the study was to provide information about the L. monocytogenes (Lm) diffusion in different Food Processing Environments using WGS to investigate the genetic diversity of the Lm isolated and to evaluate their virulence and stress resistance profiles.