Control of Persistent Listeria monocytogenes in the Meat Industry: From Detection to Prevention

<i>Listeria monocytogenes</i> poses a significant food safety risk, particularly in ready-to-eat (RTE) products, due to its persistence in food processing environments. This study aimed to assess the significance of <i>L. monocytogenes</i> contamination routes, persistence, and monitoring and control in two Spanish food industries: a fresh pork-cutting industry (Industry A) and an RTE food production industry (Industry B). A total of 698 samples from raw materials, final products, food contact surfaces (FCSs), and non-food contact surfaces (NFCSs) were analyzed using impedanciometry, isolation and identification on chromogenic agars, and molecular typing using serotyping and pulsed-field gel electrophoresis. In Industry A, <i>L. monocytogenes</i> contamination increased from 16.7% in raw materials to 53.3% in final products, with four persistent strains detected mainly on FCSs, pointing to their role in pathogen dissemination. In Industry B, the presence of <i>L. monocytogenes</i> decreased from 21.2% in raw materials to undetectable levels in the final products. Only one persistent strain was identified, mainly on NFCSs. Serotype 1/2a predominated in both environments. These findings emphasize the importance of robust monitoring, including contamination characterization, for <i>L. monocytogenes</i> prevention and control. Strengthening control measures in fresh meat processing and enhancing facility and equipment designs could improve overall hygiene and reduce the persistence of <i>L. monocytogenes</i>.