Inhibition of S. aureus invasion into mammary epithelial cells by Lactobacillus casei CIRM-BIA 667
2012
Bouchard, DAMIEN | Rault, Lucie | Berkova, Nadejda | Le Loir, Yves | Even, Sergine
Staphylococcus aureus is a major pathogen responsible for mastitis in dairy herds. S. aureus mastitis are reportedly difficult to tackle and prone to recurrence despite antibiotic treatment. The ability to invade mammary epithelial cells (MEC) and thus to evade the immune system is evoked to explain chronicity of S. aureus mastitis. One sustainable alternative to treat or prevent mastitis is the use of lactic acid bacteria (LAB), as mammary probiotic. In this study, we tested the ability of Lactobacillus casei CIRM667 to prevent invasion of bovine MEC (MAC-T) by two bovine strains of S. aureus, RF122 and Newbould305, which reproducibly induce acute and moderate mastitis, respectively. L. casei CIRM667 affected both adhesion and internalization of S. aureus in a strain-dependent manner and for specific ratios of L. casei / S. aureus. L. casei was able to reduce 40% of S. aureus RF122 adhesion and 60% to 80% of S. aureus Newbould 305 and RF122 internalization, respectively, without affecting MEC morphology and viability. Once internalized, the fate of S. aureus was not affected by L. casei. Interestingly, L. casei was internalized at a low rate but survived in MAC-T cells with a better efficiency than S. aureus RF122. Inhibition of S. aureus adhesion was maintained with heat killed L. casei whereas live L. casei were required to prevent S. aureus internalization. This first study on the antagonism of LAB against S. aureus in a mammary context opens avenues for the development of novel prevention strategies against this major pathogen.
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