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Probiotics active against listeriosis

Treatment with lactobacilli can reduce propagation throughout the body of the bacterium that causes listeriosis (Listeria monocytogenes). Obtained in the mouse by researchers from INRA and Institut Pasteur, these results enable a clearer understanding of the mechanisms of action involved in the protective effects of these probiotics, which act notably on the expression of genes in both the host and Listeria.

Test de l'utilisation du  LACTOSE  par une culture de bactéries en boites de Pétri sur milieu gélosé contenant des indicateurs colorés. © CARRERAS Florence
Updated on 02/22/2013
Published on 12/05/2012

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host (official WHO definition, 2001). To date, the established benefits of certain probiotics include stimulation of the immune system, an improvement in lactose intolerance or the inhibition of pathogenic microorganisms.  However, the mechanisms underlying these beneficial effects on human and animal health are still poorly understood.

A team from INRA and Institut Pasteur studied the action of two bacterial strains on infections due to Listeria monocytogenes, the pathogen bacterium which causes listeriosis in humans.  The two probiotic strains studied were both lactobacilli that are naturally present in the intestinal flora: Lactobacillus paracasei CNCM I-3689 and L. casei BL23.  The scientists showed in the mouse that treatment with these two lactobacillus strains could reduce the invasion of L. monocytogenes in the intestine and reduce its dissemination throughout the body.  Furthermore, they demonstrated a reduction in the expression of certain genes induced in the host during L. monocytogenes infection.  Indeed, this treatment acted on the expression of some genes in Listeria, and notably those implicated in the utilisation of certain carbon sources, which enabled the conclusion that competition for these different carbon and nitrogen sources is a crucial stage in the dissemination of Listeria.

This simultaneous analysis of the effects of lactobacillus treatment at the molecular level in both the host and in Listeria is a scientific "first".  It has provided new data on the types of mechanisms of actions involved in the protective effects of these two strains. This study will now enable a clearer understanding – and thus more effective use – of these probiotic strains to inhibit pathogenic microorganisms.

Contact(s)
Scientific contact(s):

  • Philippe Langella INRA-AgroParisTech Joint Research Unit for Food and Gut Microbiology for Human Health
  • Pascale Cossart Bacteria-Cell Interactions Research Unit, INSERM U604, INRA USC2020 Institut Pasteur
Associated Division(s):
Microbiology and the Food Chain
Associated Centre(s):
Jouy-en-Josas

Reference

Archambaud C, Nahori MA, Soubigou G, Bécavin C, Laval L, Lechat P, Smokvina T, Langella P, Lecuit M, Cossart P. Impact of lactobacilli on orally acquired listeriosis. PNAS online version 24 September 2012