Regulatory RNA-mediated regulations for adaptation of Enterococcus faecium and Staphylococcus aureus to biocide stress ; Rôles d'ARN régulateurs exprimés par Enterococcus faecium et Staphylococcus aureus en réponse au stress antiseptique

Enterococcus faecium and Staphylococcus aureus are opportunistic pathogens in human and responsible for hospital outbreaks. Antiseptics are widely used in the hospital to prevent these infections. Even at low concentrations, called subinhibitory concentrations, antiseptics likely provide a stress that bacteria must cope with. Regulatory RNAs (sRNAs) are key players in adaptive networks of bacteria to environmental changes. They have been well-studied in S. aureus by contrast with E. faecium, leading to uneven knowledges. We first aimed to characterize the sRNAs whose expression was altered under antiseptic stress of chlorhexidine, benzalkonium chloride, PVP iodine and triclosan. We showed that it led to a global repression of the studied sRNAs in E. faecium but not in S. aureus. Then, we focused on a selected sRNA of E. faecium, Ern0160 and highlighted the very first direct target of a sRNA of E. faecium. Indeed, Ern0160 specifically binds to a messenger RNA that encode a protein that has been previously described as involved in virulence in mouse model. Ern0160 downregulates the expression of its target in vitro. The impact of Ern0160 on the attenuation of virulence of E. faecium remains to be investigated in vivo to further characterize its role in E. faecium pathogenicity. ; Enterococcus faecium et Staphylococcus aureus sont des bactéries pathogènes opportunistes de l’homme responsables d’épidémies hospitalières. Les antiseptiques sont très utilisés pour prévenir la survenue de ces infections et leur présence dans l’environnement hospitalier, même à faibles concentrations, dites subinhibitrices, constitue un stress auquel ces bactéries doivent d’adapter. Les ARN régulateurs (sARN) sont des acteurs importants pour l’adaptation aux variations environnementales des bactéries. Les preuves de leur existence sont anciennes chez S. aureus mais récentes chez E. faecium, entrainant un état des connaissances très hétérogène. Dans un premier temps, nous avons souhaité caractériser les sARN dont l’expression était ...