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In vitro and in vivo characterisation of Listeria monocytogenes outbreak isolates

Stratakos, Alexandros Ch.; Ijaz, Umer Zeeshan; Ward, Patrick; Linton, Mark; Kelly, Carmel; Pinkerton, Laurette; Scates, Pam; McBride, Jane; Pet, Ioan; Criste, Adriana; Stef, Ducu; Couto, Jillian M.; Sloan, William T.; Dorrell, Nick; Wren, Brendan W.; Stef, Lavinia; Gundogdu, Ozan; Corcionivoschi, Nicolae


Umer Zeeshan Ijaz

Patrick Ward

Mark Linton

Carmel Kelly

Laurette Pinkerton

Pam Scates

Jane McBride

Ioan Pet

Adriana Criste

Ducu Stef

Jillian M. Couto

William T. Sloan

Nick Dorrell

Brendan W. Wren

Lavinia Stef

Ozan Gundogdu

Nicolae Corcionivoschi


Listeriosis is an important food-borne disease responsible for high rates of morbidity and mortality. L. monocytogenes has been the cause of several foodborne outbreaks and its ability to adapt and survive in a wide range of environmental conditions makes eradication difficult. Many L. monocytogenes strains are avirulent but have the ability to increase their virulence if exposed to environmental stresses. The aim of this study was to explain the observed increase in virulence of outbreak L. monocytogenes isolates by using phenotypic assays and whole genome sequencing. Four L. monocytogenes isolates from sweetcorn and one isolate from a raw milk (control) were sequenced and characterised using a range of phenotypic assays. The four L. monocytogenes sweetcorn isolates displayed a significant increase for in vitro adhesion and invasion of epithelial cells compared to the control isolate. They also showed a higher level of colonisation of the liver and spleen in vivo. In addition, the four L. monocytogenes isolates displayed an increased ability to form biofilms, resist heat stress and resist a combination of antimicrobials. Investigation of the genomes of the four L. monocytogenes sweet corn isolates identified Single Nucleotide Polymorphisms (SNPs) in genes, which may have a role in the observed phenotypes characteristic of these strains, particularly in response to survival properties within the environment or in terms of virulence. We highlight the importance of combining whole genomic sequencing with phenotypic characterisation as a key element in the investigation of outbreaks of foodborne pathogens.


Stratakos, A. C., Ijaz, U. Z., Ward, P., Linton, M., Kelly, C., Pinkerton, L., …Corcionivoschi, N. (2020). In vitro and in vivo characterisation of Listeria monocytogenes outbreak isolates. Food Control, 107,

Journal Article Type Article
Acceptance Date Jul 20, 2019
Online Publication Date Jul 21, 2019
Publication Date Jan 1, 2020
Deposit Date Sep 17, 2019
Journal Food Control
Print ISSN 0956-7135
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 107
Article Number 106784
Keywords Biotechnology; Food Science; Listeria monocytogenes; Outbreaks; Environment; Genomics; Virulence
Public URL
Additional Information This article is maintained by: Elsevier; Article Title: In vitro and in vivo characterisation of Listeria monocytogenes outbreak isolates; Journal Title: Food Control; CrossRef DOI link to publisher maintained version:; Content Type: article; Copyright: © 2019 The Authors. Published by Elsevier Ltd.


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