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

Listeria monocytogenes 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 L. monocytogenes 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, L. monocytogenes 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 L. monocytogenes 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 L. monocytogenes 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 L. monocytogenes.