11-Year Genomic Surveillance of Listeria monocytogenes in Coastal China: Comparative Analysis of Environmental, Food, and Clinical Strains Reveals Transnational Transmission Risks

Listeria monocytogenes (Lm) poses significant public health risks through contaminated foods. This 11-year genomic surveillance (2014–2024) analyzed 2,150 samples from food chains and clinical cases in Yantai, China. Whole-genome sequencing of 45 strains (21 local isolates, 24 global references) revealed key findings: Prevalence: Overall detection rate of 1.77%, with edible fungi showing the highest contamination (20%, p < 0.05 vs. other categories). Antimicrobial Resistance: Universal carriage of lin, mprF, and norB genes; 33.3% harbored fosX. Virulence Determinants: 83 virulence genes identified, including conserved invasion/adherence factors (inlA, hly) and variable exotoxin genes (76.2% loss rate). Phylogenetics: Dominant serotype 1/2a (52.4%) and ST121/ST3/ST8 clones (23.8% each). Environmental isolates clustered with international strains (Brazil, USA, Spain) with < 10 SNP differences. These findings underscore the need for enhanced environmental monitoring in food processing facilities and global genomic databases for outbreak tracing.