Molecular characterization and drug resistance analysis based on whole-genome sequencing of Listeria monocytogenes isolated from food and patients in Liaocheng City from 2019 to 2022

Abstract

ObjectiveThe genomic characteristics， toxicity， drug resistance and genetic diversity of Listeria monocytogenes （Lm） isolated from food and patients based on whole genome sequencing （WGS） in Liaocheng City from 2019 to 2022 were investigated.MethodsThe Lm strains isolated from food and patients were detected by the drug sensitivity test and WGS. The whole genome sequencing data was spliced and assembled by MGAP to carry out gene prediction and functional annotation on the assembled genome， MLST， production of cg MLST minimum spanning tree. The genetic evolution of 18 domestic and foreign foodborne Lm isolated strains obtained from NCBI were analyzed by wg-SNP method.ResultsThe genome size of 33 Lm isolates was 2.89-3.41 Mb， and the CG content ranged from 37.81% to 37.97%. The strains could be divided into 6 ST types （ST9， ST121， ST8， ST87， ST155， ST101）， corresponding to 6 clonal complex groups （CC9， CC121， CC8， CC87， CC155， CC101）. The strains carried fosX and mprF resistance gene， 18 other virulence genes such as lplA1 and prsA2， with varying degrees of deletion of virulence genes. 2 strains were resistant to tetracycline and 1 strain was resistant to lincomycin. The stains carried virulence islands LIPI-1 and LIPI-2 without virulence islands LIPI-3 and LIPI-4. The genetic evolution analysis of wg-SNPs， cgMLST and phylogenetic tree based on single-copy core protein sequence showed that the molecular typing of 33 Lm strains was with high diversity in molecular typing. Patient derived strains were closely related to food isolates， and food isolates were closely related to foreign outbreak isolates in evolutionary relationships.ConclusionThe strains of Lm isolated from food and patients both carry virulence genes with certain potential pathogenic ability. The drug resistance of the isolated strains is not serious. Molecular types exhibit diversity. The close genetic relationship between strains from food sources and patient isolates suggests that the potential risks of foodborne infections in commercially available food.

Keywords

• listeria monocytocytogenes
• whole genome sequencing
• toxicity
• drug resistance
• foodborne pathogenic