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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
12:50

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Published on: August 9, 2011

Plant-derived antimicrobials reduce Listeria monocytogenes virulence factors in vitro, and down-regulate expression

Abhinav Upadhyay1, Anup Kollanoor Johny, Mary Anne Roshni Amalaradjou

  • 1Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA.

International Journal of Food Microbiology
|May 22, 2012
PubMed

Insights

Plant-derived antimicrobials trans-cinnamaldehyde, carvacrol, and thymol effectively reduced Listeria monocytogenes (LM) virulence factors, including attachment, invasion, and gene expression, offering potential for controlling foodborne listeriosis.

Area of Science:

  • Food Microbiology
  • Pathogen Control
  • Antimicrobial Agents

Background:

  • Listeria monocytogenes (LM) is a significant foodborne pathogen responsible for severe human infections like septicemia and meningitis.
  • LM pathogenesis involves attachment to and invasion of host cells, followed by systemic spread, with motility, hemolysin, and lecithinase as key virulence factors.

Purpose of the Study:

  • To evaluate the efficacy of sub-inhibitory concentrations (SICs) of three GRAS plant-derived compounds—trans-cinnamaldehyde (TC), carvacrol (CR), and thymol (TY)—in mitigating LM virulence.
  • To assess the impact of these compounds on LM's adhesion, invasion, motility, hemolysin, and lecithinase production.

Main Methods:

  • Human colon adenocarcinoma (Caco-2) and brain microvascular endothelial cells (HBMEC) were used to model LM interaction.
  • Sub-inhibitory concentrations (SICs) of TC, CR, and TY were applied to assess their effects on LM virulence factors.
  • Real-time PCR was employed to quantify the expression of LM virulence genes.

Main Results:

  • All three plant antimicrobials significantly reduced LM adhesion to and invasion of both Caco-2 and HBMEC cells (p<0.05).
  • TC, CR, and TY demonstrably decreased LM motility, hemolysin production, and lecithinase activity (p<0.05).
  • Gene expression analysis showed that TC, CR, and TY down-regulated key LM virulence genes by over 3.0-fold compared to controls (p<0.05).

Conclusions:

  • Trans-cinnamaldehyde, carvacrol, and thymol exhibit significant potential as natural agents to control Listeria monocytogenes infection.
  • These compounds effectively inhibit critical virulence factors and reduce bacterial adhesion and invasion.
  • Further in vivo studies are warranted to validate these promising in vitro findings for practical applications in listeriosis control.

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