Molecular Subtyping Methods for<i>Listeria monocytogenes</i>

Lomonaco, Sara; Nucera, Daniele

doi:10.1002/9781118278666.ch13

Cited by 4 publications

(2 citation statements)

References 141 publications

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“…17 the bacterium which is essential for source tracking in clinical and food environments (Lomonaco and Nucera, 2012). This observation is corroborated with these results which also demonstrate that phylogenies constructed using concatenated MLST sequences result in a tree with comparably low confidence and low discriminatory power (Appendix B).…”

Section: Accepted Manuscriptsupporting

confidence: 67%

Listeria monocytogenes isolates from ready to eat plant produce are diverse and have virulence potential

Smith

Hearn

Taylor

et al. 2019

International Journal of Food Microbiology

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Listeria monocytogenes is sporadically detected on a range of ready to eat fresh produce lines, such as spinach and rocket, and is a threat to public health. However, little is known about the diversity of L. monocytogenes present on fresh produce and their potential pathogenicity. In this work, fifteen Listeria monocytogenes isolates from the UK fresh produce supply chain were characterised using whole genome sequencing (WGS). Additionally, isolates were characterised based on their ability to form biofilm. Whole genome sequencing data was used to determine the sequence type of isolates based on multi-locus sequence typing (MLST), construct a core single nucleotide polymorphism (SNP) phylogeny and determine the presence of virulence and resistance associated genes. MLST revealed 9 distinct sequence types (STs) spanning 2 lineages (I & II) with one isolate belonging to the ST6 subtype, strains from which have been recently implicated in two large, food-associated L. monocytogenes outbreaks in South Africa and across Europe. Although most of the 15 isolates were different, comparison of core genome SNPs showed 4 pairs of 'indistinguishable' strains (< 5 SNPs difference). Virulence profiling revealed that some isolates completely lacked the Listeria pathogenicity island-3 (LIPI-3) amongst other virulence factors. Investigation of the inlA gene showed that no strains in this study contained a premature stop codon (PMSC), an indicator of ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T2 attenuated virulence. Assessment of biofilm production showed that isolates found in the fresh produce supply chain differ in their ability to form biofilm. This trait is considered important for L.monocytogenes to persist in environments associated with food production and processing. Overall the work indicates that a genetically diverse range of L. monocytogenes strains is present in the UK fresh produce supply chain and the virulence profiles found suggests that at least some of the strains are capable of causing human illness. Interestingly, the presence of some genetically indistinguishable isolates within the 15 isolates examined suggests that cross-contamination in the fresh produce environment does occur. These findings have useful implications in terms of food safety and for informing microbial surveillance programmes in the UK fresh produce supply chain.

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Section: Accepted Manuscriptsupporting

confidence: 67%

Listeria monocytogenes isolates from ready to eat plant produce are diverse and have virulence potential

Smith

Hearn

Taylor

et al. 2019

International Journal of Food Microbiology

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“…Though PFGE is a useful tool for the characterization of the subtypes of L. monocytogenes isolates, it lacks discriminatory power to distinguish among closely related bacterial strains, which is essential for source tracking (Lomonaco and Nucera, 2014). Thus, WGS was used for obtaining better FIGURE 2 | Minimum spanning tree of cgMLST data for 20 L. monocytogenes isolates.…”

Section: Discussionmentioning

confidence: 99%

Identification of Listeria monocytogenes Contamination in a Ready-to-Eat Meat Processing Plant in China

Zhang

Que²,

et al. 2021

Front. Microbiol.

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Listeria monocytogenes is the etiologic agent of listeriosis, which remains a significant public health concern in many countries due to its high case-fatality rate. The constant risk of L. monocytogenes transmission to consumers remains a central challenge in the food production industry. At present, there is very little known about L. monocytogenes contamination in ready-to-eat (RTE) processing plants in China. In this study, L. monocytogenes in an RTE meat processing plant in Shanghai municipality was characterized using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Furthermore, the biofilm formation ability of the pathogen was also tested. Results revealed that L. monocytogenes isolates were present in 12 samples out of the 48 samples investigated. Most of them (66.7%, 8/12) were identified from the processing facilities irrespective of observed hygiene levels of aerobic plate count (APC) and coliforms. Coliforms were present in only one processing area. ST5 (1/2b) isolates were predominant (83.3%, 10/12) and were identified in two dominant pulsotypes (PTs) (three in PT3 and seven in PT4, respectively). Results of the core-genome multi-locus sequence typing (cgMLST) showed that ST5 in three PTs (PT1, PT3, and PT4) had 0–8 alleles, which confirmed that clonal transmission occurred in the RTE meat processing facilities. In addition, the biofilm formation test confirmed that the isolates from the processing facilities could form biofilms, which helped them colonize and facilitate persistence in the environment. These results indicated that common sanitation procedures regularly applied in the processing environment were efficient but not sufficient to remove L. monocytogenes isolates, especially biofilm of L. monocytogenes. Furthermore, the ST5 isolates in this study exhibited 12 alleles with one ST5 clinical isolate, which contributes to the understanding of the potential pathogenic risk that L. monocytogenes in RTE meat processing equipment posed to consumers. Therefore, strong hygienic measures, especially sanitation procedures for biofilms eradication, should be implemented to ensure the safety of raw materials. Meanwhile, continuous surveillance might be vital for the prevention and control of listeriosis caused by L. monocytogenes.

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Contamination of chicken carcasses and the abattoir environment withListeria monocytogenesin Taiwan

Lin

Adams

Huang

et al. 2021

British Poultry Science

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Molecular Subtyping Methods forListeria monocytogenes

Cited by 4 publications

References 141 publications

Listeria monocytogenes isolates from ready to eat plant produce are diverse and have virulence potential

Listeria monocytogenes isolates from ready to eat plant produce are diverse and have virulence potential

Identification of Listeria monocytogenes Contamination in a Ready-to-Eat Meat Processing Plant in China

Contamination of chicken carcasses and the abattoir environment withListeria monocytogenesin Taiwan

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