First Report on the Finding of Listeria mnocytogenes ST121 Strain in a Dolphin Brain

Abstract

Listeria monocytogenes (Lm) 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 Tn6188, 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 actA gene and inlA 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.

Phylogenetic Analysis and Genome-Wide Association Study Applied to an Italian Listeria monocytogenes Outbreak

“…This latter approach compares a large set of genomic data and associates them to specific phenotypic traits, allowing for the identification of markers or indicators of specific phenotypes. The GWAS analysis has been successfully used for identifying Lm genetic determinants involved in biofilm formation ( Lee et al, 2019 ), persistence ( Fritsch et al, 2019 ; Palma et al, 2020 ), and virulence ( Sévellec et al, 2020 ).…”

Genetic, Endocrine, and Microbiological Assessments of Blue, Humpback and Killer Whale Health using Unoccupied Aerial Systems

“…While nominally commensal in healthy animals, microbes residing on the skin or in the respiratory tract may become pathogenic or more invasive in stressed or immunosuppressed individuals. For example, in harbor porpoises that were immunosuppressed by exposure to heavy metals (Bennett et al 2001), and in recent observation of Listeria mnocytogenes ST121 infection that crossed the blood‐brain barrier in an immunosuppressed dolphin exposed to polychlorinated biphenyl (Sévellec et al 2020). Thus, identification of respiratory microbiome species facilitates follow up on the broad classification of the microbial community with more directed experiments designed to characterize pathogens identified in stranded animals.…”

Genetic Diversity and Relationships of Listeria monocytogenes Serogroup IIa Isolated in Poland

“…Recent application of whole-genome sequencing (WGS) into bacterial molecular characterization provides much data on the relationship of L. monocytogenes from different sources and allows the classification of the strains into evolutionary lines and genetic types [ 15 , 16 , 17 ]. Based on the WGS, the multilocus sequence typing (MLST) approach allows classification of L. monocytogenes into clonal complexes (CCs) and sequence types (STs), which are linked with persistence of the strains in food, food production environments or with a high potential to cause listeriosis [ 18 , 19 , 20 , 21 ]. It has been shown that L. monocytogenes of CC121 classified as serogroup IIa has been often isolated from different food processing plants for several years, which makes them serious problems for the food industry and poses a potential threat for consumers [ 20 ].…”

“…Based on the WGS, the multilocus sequence typing (MLST) approach allows classification of L. monocytogenes into clonal complexes (CCs) and sequence types (STs), which are linked with persistence of the strains in food, food production environments or with a high potential to cause listeriosis [ 18 , 19 , 20 , 21 ]. It has been shown that L. monocytogenes of CC121 classified as serogroup IIa has been often isolated from different food processing plants for several years, which makes them serious problems for the food industry and poses a potential threat for consumers [ 20 ]. Other data also suggest that L. monocytogenes IIa serogroup, classified to CC8, CC155, and other clonal complexes, have persistent properties and have been identified in different niches or sources [ 15 , 17 , 18 ].…”