Analysis of genomic characteristics,antimicrobial and pathogenic genes of Listeria monocytogens in commercial food in Xianyang City

Abstract

ObjectiveTo use whole genome sequencing （WGS） to analysis the genomic characteristics， the antimicrobial resistance and virulence genotypes of 64 Listeria monocytogenes strains isolated from commercial food in Xianyang City.MethodsSixty four Listeria monocytogenes were isolated and the susceptibilities were determined by broth microdilution. After the whole genome sequencing， using bioinformatics software for genome annotation， phylogenetic tree construction， genome features and genetic components analysis.ResultsAll isolates were found to be susceptible to ampicillin， Penicillin， meropenem， trimethoprim-sulfamethoxazole， vancomycin. 2 isolates were resistant to tetracycline and erythromycin at the same time. All isotates were categorized into three different lineages and 15 CCs， Lineage Ⅰ and Ⅱ were the predominant types. The genotypes of 2 resistant isolates correlated well with its resistant phenotype. Up and down stream analysis of the genetic context， in which these resistant genes were found， suggested that they may have been acquired from Erysipelothrix rhusiopathiae， Enterococcus and plasmid. All the isolates harboured the LIPI-1 and LIPI-2， subset of lineage Ⅰ isotates harboured LIPI-3 or LIPI-4 with potential pathogenicity. Lineage Ⅱ isotates harboured more plasmids and genes linked to stress adaptation . The premature stop codon （PMSC） mutation in inlA more frequently happened in lineage Ⅱ and may reduce virulence.ConclusionThe genome of Listeria monocytogenes in commercial food in Xianyang City is stable. Acquires resistance existed in this bacterium， and can be a potential public health risk due to its high harboring rate of virulence genes. Lineage Ⅰ and Lineage Ⅱ isolates were differ in virulence genes， stress adaptation genes and plasmids harboring， indicating differences among subtypes. This findings would be helpful to the surveillance and control of this foodborne pathogen in Xianyang City.

Keywords

• listeria monocytogenes
• whole genome sequencing
• antimicrobial
• virulence