Potential Ad Hoc Markers of Persistence and Virulence in Canadian Listeria monocytogenes Food and Clinical Isolates

Jacqueline Upham, Stephen Chen, Elizabeth Boutilier, Lisa Hodges, Mikaela Eisebraun, Matthew A. Croxen, Alex Fortuna, Gustavo V. Mallo, Rafael A. Garduño

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The Listeria monocytogenes gene inlA, encoding a surface virulence protein, was examined for the presence of premature stop codon (PMSC) mutations in 82 isolates obtained by the Canadian Food Inspection Agency (CFIA) from foods and food contact surfaces. These mutations were coanalyzed for the presence of stress survival islet 1 (SSI-1) and for the abilities of the isolates to invade Caco-2 intestinal epithelial cells and form biofilms on polystyrene. PMSC mutations were present in one-third of the isolates (predominantly those of serogroup 1/2a), and their presence was correlated with a noninvasive phenotype. The presence of SSI-1 and the ability to form biofilms were also linked to the 1/2a serogroup. Serogroup 4b isolates lacked inlA PMSC mutations and were invasive, but neither formed biofilms nor carried SSI-1. To expand upon these experimental findings, an in silico analysis was performed on L. monocytogenes genomes from Canadian databases of 278 food isolates and 607 clinical isolates. The prevalence of inlA PMSC mutations in genomes of food isolates was significantly higher (P, 0.0001) than that in clinical isolates. Also, a three-codon deletion in inlA associated with a hyperinvasive phenotype was more prevalent in genomes from clinical isolates (primarily of clonal complex 6, serogroup 4b) than in those from food isolates (P, 0.001). In contrast, SSI-1 was significantly overrepresented (P, 0.001) in genomes from food isolates. We propose the hypothesis that SSI-1 and inlA play a role in the evolution of Canadian L. monocytogenes strains into either a virulent (represented by serogroup 4b clinical isolates) or an environmentally persistent (represented by serogroup 1/2a food isolates) phenotype. The combined presence of SSI-1 and inlA PMSC mutations have potential for use as genetic markers for risk assessment when L. monocytogenes is recovered from foods, indicating low potential for pathogenesis.

Original languageEnglish
Pages (from-to)1909-1921
Number of pages13
JournalJournal of Food Protection
Volume82
Issue number11
DOIs
Publication statusPublished - 2019

Bibliographical note

Funding Information:
Published 2019 by the International Association for Food Protection Copyright ©, Her Majesty the Queen in Right of Canada, as represented by the Canadian Food Inspection Agency

Publisher Copyright:
Copyright ©, Her Majesty the Queen in Right of Canada, as represented by the Canadian Food Inspection Agency

ASJC Scopus Subject Areas

  • Food Science
  • Microbiology

Fingerprint

Dive into the research topics of 'Potential Ad Hoc Markers of Persistence and Virulence in Canadian Listeria monocytogenes Food and Clinical Isolates'. Together they form a unique fingerprint.

Cite this