Whole-Genome Sequencing-Based Characterization of a Listeria monocytogenes Strain from an Aborted Water Buffalo in Southern Italy

Abstract

Listeria monocytogenes is a Gram-positive pathogen causing life-threatening infections both in humans and animals. In livestock farms, it can persist for a long time and primarily causes uterine infections and encephalitis in farmed animals. Whole genome sequencing (WGS) is currently becoming the best method for molecular typing of this pathogen due to its high discriminatory power and efficiency of characterization. This study describes the WGS-based characterization of an L. monocytogenes strain from an aborted water buffalo fetus in southern Italy. The strain under study was classified as molecular serogroup IVb, phylogenetic lineage I, MLST sequence type 6, Clonal Complex 6, and cgMLST type CT3331, sublineage 6. Molecular analysis indicated the presence of 61 virulence genes and 4 antibiotic resistance genes. Phylogenetic analysis, including all the publicly available European L. monocytogenes serogroup IVb isolates, indicated that our strain clusterized with all the other CC6 strains and that different CCs were variably distributed within countries and isolation sources. This study contributes to the current understanding of the genetic diversity of L. monocytogenes from animal sources and highlights how the WGS strategy can provide insights into the pathogenic potential of this microorganism, acting as an important tool for epidemiological studies.

Loggerhead Sea Turtle as Possible Source of Transmission for Zoonotic Listeriosis in the Marine Environment

“…On the other side, numerous descriptions of L. monocytogenes in marine molluscs and fish are present in the Literature [ 7 , 46 , 47 ]; specifically, among these animals, the ST6 has been reported [ 29 ]. Among animals, this sequence type has additionally been described in an aborted water buffalo fetus in Southern Italy [ 48 ] and from the liver of a white-faced saki ( Pithecia pithecia ) that died following septicemic listeriosis [ 49 ].…”

“…Elusive aquatic species that present criticalities such as Caretta caretta might be tested by means of environmental (e) DNA [ 50 ], which allows to perform sea turtle population genetic studies as well as pathogen monitoring. This might also be applied for evaluating the potential sentinel of this species for zoonotic and terrestrial pathogens in the marine environment [ 48 ], as suggested for other aquatic species, as an indicator of the anthropic pressure.…”