Whole-Genome Sequencing-Based Characterization of Listeria monocytogenes from Fish and Fish Production Environments in Poland

Abstract

Listeria monocytogenes, an important foodborne pathogen, may be present in different kinds of food and in food processing environments where it can persist for a long time. In this study, 28 L. monocytogenes isolates from fish and fish manufactures were characterized by whole genome sequencing (WGS). Core genome multilocus sequence typing (cgMLST) analysis was applied to compare the present isolates with publicly available genomes of L. monocytogenes strains recovered worldwide from food and from humans with listeriosis. All but one (96.4%) of the examined isolates belonged to molecular serogroup IIa, and one isolate (3.6%) was classified to serogroup IVb. The isolates of group IIa were mainly of MLST sequence types ST121 (13 strains) and ST8 (four strains) whereas the isolate of serogroup IVb was classified to ST1. Strains of serogroup IIa were further subtyped into eight different sublineages with the most numerous being SL121 (13; 48.1% strains) which belonged to six cgMLST types. The majority of strains, irrespective of the genotypic subtype, had the same antimicrobial resistance profile. The cluster analysis identified several molecular clones typical for L. monocytogenes isolated from similar sources in other countries; however, novel molecular cgMLST types not present in the Listeria database were also identified.

Intensive Environmental Surveillance Plan for Listeria monocytogenes in Food Producing Plants and Retail Stores of Central Italy: Prevalence and Genetic Diversity

“…The SSIs are known to confer resistance to stresses, in particular the SSI-1, linked to environmental stress, such as low pH, high osmolarity, bile and nisin, and the SSI-2, linked to tolerance to alkaline and oxidative stresses. According to our results, SSI-1 were frequently observed in Lm strains belonging to different clones, whereas the SSI-2 genes were mainly found in CC121 isolates [43], suggesting a possible contribution to strains adaptation and persistence in FPPs [44].…”

Application of Whole Genome Sequencing to Aid in Deciphering the Persistence Potential of Listeria monocytogenes in Food Production Environments

“…As mentioned previously, the discriminatory power of WGS is unparalleled. Many researchers have utilized this technology in order to reduce the ambiguity of the persister phenotype, described above [ 78 , 79 , 80 , 81 ]. This method is useful for the detection of persistent isolates as well as outbreak investigations.…”

Genetic Diversity and Relationships of Listeria monocytogenes Serogroup IIa Isolated in Poland

“…All but one strain were recovered from RTE food (17; 60.7%) and food production environments (10; 35.7%). L. monocytogenes of ST8, such as the characterized above ST121, was previously often isolated from food and food production areas, which suggests that strains of such sequence type can survive in adverse conditions present in such environments [ 13 , 74 , 77 , 79 , 80 ]. Furthermore, such isolates have probably increased virulence properties since they were also responsible for human listeriosis cases [ 47 , 59 , 81 , 82 ].…”

“…Isolates belonging to CC8 were also previously identified in food and in humans suffering from listeriosis [ 18 , 26 , 45 , 46 , 47 , 83 ]. However, there are also studies in which none of the L. monocytogenes classified to CC8 was positive for the Tn6188_qac ( ermC ) marker [ 49 , 80 ].…”