Small-Scale Comparative Genomic Analysis of Listeria monocytogenes Isolated from Environments of Salmon Processing Plants and Human Cases in Norway

Listeria monocytogenes is a food-borne bacterium that give rise to the potentially life-threatening disease listeriosis. Listeriosis has been mandatorily notifiable in Norway since 1991. All clinical L. isolates are sent Norwegian Institute of Public Health (NIPH) for typing. Since 2005 Multi-Locus Variable number tandem repeats Analysis (MLVA) used typing but was recently replaced by whole genome sequencing using core Sequence Typing (cgMLST). In present study, collected at salmon processing plants 2007 (n = 12) and 2015 14) were first subject MLVA. Twelve with matching MLVA profile sampling time selected from strain collection NIPH. Twenty-one all sequenced compared cgMLST silico detection virulence genes. revealed four pairs environmental–human ?10 allelic differences over 1708 genes, indicating they may be assigned as clonal, implication descended same recent ancestor. No relevant difference carriage genes found between environmental or human isolates. The study shows strains genetically resemble contemporary listeriosis circulate slaughterhouses, carry