Genetic diversity, antibiotic resistance, and virulence profiles of Listeria monocytogenes from retail meat and meat processing.

Human listeriosis outbreaks are often associated with consumption of contaminated food, especially meat products. To better understand meat contamination of L. monocytogenes, whole genome sequencing(WGS) was performed on all detected isolates to investigate genetic relationships between retail markets and slaughterhouses. 110 and 13 isolates were isolated from 1914 food samples and 67 food and environmental samples, respectively. IIa (51/123,41.5%) and IIc (7/123,5.7%) were detected as the dominant serogroups of 123 L. monocytogenes isolates.Most isolates were penicillin-resistant (22/123,17.9%) in the phenotypic test, and all isolates were also found to be susceptible to ampicillin, meropenem, and vancomycin. All of them harbored virulence-associated genes and premature stop codons (PMSCs) in inlA genes were occurred in 35 strains. 22 multilocus sequence types and 19 clonal complexes were identified with ST9 being most common. This study also showed the prevalence and uniqueness of strains from Jilin, China compared with worldwide epidemic international strains. The findings of this study will contribute to the epidemiological understanding of transmission of L. monocytogenes from production and circulation in the region of northern China.