ABSTRACT
Some opportunistic human pathogens can be found in the endogenous ecosystems (e.g., retronasal, mammary, intestinal, or vaginal) of the human host and adopt a commensal lifestyle therein (Reid and Bruce 2006). Other pathogens transiently colonize, invade the host’s tissues and/or produce virulence factors and thus exert adverse effects on host health. In both cases, probiotic lactic acid bacteria (LAB) can be envisioned as natural killers of pathogenic microorganisms through the production of bacteriocins (see Chapter 2), oxygen peroxide or other deleterious compounds. Although some bacteriocins display high specifi city of spectrum, the killing activity of some other molecules does not always prove to be selective. Therefore, to complement these weapons, recent experimental designs were developed to evaluate LAB capability to impair or modulate adhesion, invasion, or virulence expression in targeted pathogens, thus highlighting added value
INRA, UMR1253 STLO, F-35042 Rennes, France. Agrocampus Ouest, UMR1253 STLO, F-35042 Rennes, France. * Corresponding author: yves.leloir@rennes.inra.fr
to their probiotic potential. Such effects on these early steps of infection are of primary importance and can be considered as prevention strategies. Other studies confi rm the possibility of employing LAB to treat established infections notably through their capacity to neutralize toxins, either by degradation or titration.
