Whole Genome Sequence–Based Surveillance of Human Clinical <i>Listeria monocytogenes</i> Isolates From Switzerland, 2019–2024

Background: s is a foodborne pathogen that poses a significant public health risk due to the high case-fatality rate of listeriosis. Whole genome sequencing (WGS) is critical for identifying outbreak clusters and enables high-resolution characterization of isolates. Methods: isolates from human cases of listeriosis occurring in Switzerland between 2019 and 2024. WGS was used to identify disease clusters and characterize the phylogenetic relatedness, virulence profiles, and antimicrobial resistance genes of the isolates. Results: pathogenicity island (LIPI)-3 was found predominantly among CC1, CC4, and CC6 isolates. LIPI-4 was present in CC4 and CC388, and in infrequently occurring ST32, ST213, ST217, ST220, ST382, and ST1460. Conclusions: .