Genomic characterization of persistent Listeria monocytogenes strains isolated from food and production environments in Chile between 2000 and 2020.

Abstract

Background: Listeria monocytogenes poses a risk to vulnerable populations, resulting in cases and outbreaks with high mortality rates globally and in Chile.  Aim: Genomically characterize strains of L. monocytogenes isolated from food and production environments in Chile (2000–2020) using whole genome sequencing to contribute to traceability, epidemiological surveillance, and optimize control strategies in public health and food safety. Methodology: A total of 116 L. monocytogenes genomes from food and production environments were analyzed. The serotype, sequence types (ST), clonal complex (CC), and core genome MLST were determined, as well as genes associated with antimicrobial resistance and virulence. Results: L. monocytogenes was prevalent in meat, fruit, vegetables, and dairy products. Serotypes 1/2a, 1/2b, and 4b predominated, while ST1, ST5, ST8, and ST9 were predominant. Twenty-one clusters were identified, with ST1, ST5, and ST8 standing out for their persistence over time. 100% of the genomes have clpCEP heat stress genes, bcrBC benzalkonium chloride resistance genes, and inlA, prfA, and hly virulence genes. Conclusions: The persistence of L. monocytogenes was evident during the study period. Therefore, it is recommended that genomic surveillance of L. monocytogenes be implemented in food and clinical cases in Chile.