First Report on the Finding of <i>Listeria mnocytogenes</i> ST121 Strain in a Dolphin Brain

• Main Authors: Yann Sévellec, Marina Torresi, Benjamin Félix, Féderica Palma, Gabriella Centorotola, Stefano Bilei, Matteo Senese, Giuliana Terracciano, Jean-Charles Leblanc, Francesco Pomilio, Sophie Roussel
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Pathogens
• Subjects: <i>Listeria monocytogenes</i>; ST121; dolphin; wildlife; food; genomic comparison
• Online Access: https://www.mdpi.com/2076-0817/9/10/802

<i>Listeria monocytogenes</i> (<i>Lm</i>) is a ubiquitous bacterium that causes the foodborne illness, listeriosis. Clonal complexes (CC), such as CC121, are overrepresented in the food production industry, and are rarely reported in animals and the environment. Working within a European-wide project, we investigated the routes by which strains are transmitted from environments and animals to food and the food production environment (FPE). In this context, we report, for the first time, the occurrence of a ST121 (CC121) strain isolated from a dolphin brain. The genome was compared with the genomes of 376 CC121 strains. Genomic comparisons showed that 16 strains isolated from food were the closest to the dolphin strain. Like most of the food strains analyzed here, the dolphin strain included genomic features (transposon Tn<i>6188</i>, plasmid pLM6179), both described as being associated with the strain’s adaptation to the FPE. Like all 376 strains, the dolphin strain contained a truncated <i>actA</i> gene and <i>inlA</i> gene, both described as being associated with attenuated virulence. Despite this fact, the strain was able to cross blood-brain barrier in immunosuppressed dolphin exposed polychlorinated biphenyl and invaded by parasites. Our data suggest that the dolphin was infected by a food-related strain released into the Mediterranean Sea.