Whole-genome sequencing reveals genomic characterization of Listeria monocytogenes from food in China

Abstract

IntroductionListeria monocytogenes is a foodborne bacterium that could persist in food and food processing environments for a long time. Understanding the population structure and genomic characterization of foodborne L. monocytogenes is essential for the prevention and control of listeriosis.MethodsA total of 322 foodborne L. monocytogenes isolates from 13 geographical locations and four food sources in China between 2000 and 2018 were selected for whole-genome sequencing.ResultsIn silico subtyping divided the 322 isolates into five serogroups, 35 sequence types (STs), 26 clonal complexes (CCs) and four lineages. Serogroup IIa was the most prevalent serogroup and ST9 was the most prevalent ST of foodborne L. monocytogenes strains isolated in China. The in-depth phylogenetic analysis on CC9 revealed that ST122 clone might be original from ST9 clone. Furthermore, 23 potentially relevant clusters were identified by pair-wised whole-genome single nucleotide polymorphism analysis, indicating that persistent- and/or cross-contamination had occurred in markets in China. ST8 and ST121 were the second and third top STs of L. monocytogenes in China, which had heterogeneity with that of L. monocytogenes isolates from other countries. The antibiotic resistance genes aacA4, tetM, tetS, dfrG carried by different mobile elements were found in L. monocytogenes strains. One lineage II strain carrying Listeria Pathogenicity Island 3 was first reported. In addition, a novel type of premature stop codon in inlA gene was identified in this study.DiscussionThese findings revealed the genomic characteristics and evolutionary relationship of foodborne L. monocytogenes in China on a scale larger than previous studies, which further confirmed that whole-genome sequencing analysis would be a helpful tool for routine surveillance and source-tracing investigation.

Clinical Characteristics and Fatality Risk Factors for Patients with Listeria monocytogenes Infection: A 12-Year Hospital-Based Study in Xi’an, China

“…It was shown that the evolution rate of L. monocytogenes was lower, leading to a specific geographical distribution of L. monocytogenes [ 24 ]. Although we did not perform the molecular characterization analysis of L. monocytogenes isolates, the lower fatality rate in Xi’an and other cities in China might be associated with the differences in predominance of serogroup, sequence types, and clone complexes between L. monocytogenes strains in China and other countries/regions [ 25 – 27 ]. L. monocytogenes infections analyzed in this study revealed that human listeriosis in Xi’an was mainly concentrated in spring and summer, which was related to the transmission feature of food-borne disease by contaminated food.…”

Unveiling the Mutations and Conservation of InlA in Listeria monocytogenes

“…MEGA software (version 11) was used to align and obtain amino acid sequences of the InlA. Protein types of InlA were identified by comparing them with the reference strain (EGD-e, NC_003210.1) by using local BLAST methods [ 20 ]. An amino acid difference is a new protein sequence type (PST).…”

“…For example, in the United States, the detection of L. monocytogenes strains harboring stop codons has been demonstrated at 35–45% in food isolates, while human isolates only account for 5.1% [ 17 ]. At present, many types of PMSC mutations in the InlA have been documented [ 18 , 19 , 20 ]. However, Wang et al showed that the presence of PMSC type 19 at position 976 may not impact the ability of L. monocytogenes to adhere to and invade epithelial cells [ 21 ].…”

Whole-Genome Analysis of Stress Resistance-Related Genes inListeria monocytogenes

“…Their research provided valuable information for monitoring listeriosis by thoroughly understanding the genetic diversity among clinically isolated strains. Similarly, Ji et al (2023) performed WGS on 322 foodborne L. monocytogenes strains from 13 regions and four food sources in China, and analyzed their antibiotic resistance and virulence genes in detail. In addition, through WGS, Song et al (2022) clarified the population structure and characteristics of 207 ST9 L. monocytogenes strains from 14 different countries and regions.…”

“…Meanwhile, Hingston et al (2017) used WGS to reveal the potential relationship between L. monocytogenes genotypes and food-related stress tolerance phenotypes. All these studies demonstrate that WGS can reveal significant differences in genotypes and stress responses among different strains, provide more detailed molecular characteristics, and being helpful to better understand their genetic relationships (Ji et al 2023). This is of great value to our understanding of the biology and epidemiological research of L. monocytogenes .…”