title: Stress Conditions Induced by Carvacrol and Cinnamaldehyde on Acinetobacter baumannii.
abstract: Acinetobacter baumannii has emerged as a major cause of nosocomial infections. The ability of A. baumannii to display various resistance mechanisms against antibiotics has transformed it into a successful nosocomial pathogen. The limited number of antibiotics in development and the disengagement of the pharmaceutical industry have prompted the development of innovative strategies. One of these strategies is the use of essential oils, especially aromatic compounds that are potent antibacterial molecules. Among them, the combination of carvacrol and cinnamaldehyde has already demonstrated antibacterial efficacy against A. baumannii. The aim of this study was to determine the biological effects of these two compounds in A. baumannii, describing their effect on the rRNA and gene regulation under environmental stress conditions. Results demonstrated rRNA degradation by the carvacrol/cinnamaldehyde mixture, and this effect was due to carvacrol. Degradation was conserved after encapsulation of the mixture in lipid nanocapsules. Results showed an upregulation of the genes coding for heat shock proteins, such as groES, groEL, dnaK, clpB, and the catalase katE, after exposure to carvacrol/cinnamaldehyde mixture. The catalase was upregulated after carvacrol exposure wich is related to an oxidative stress. The combination of thiourea (hydroxyl radical scavenger) and carvacrol demonstrated a potent bactericidal effect. These results underline the development of defense strategies of the bacteria by synthesis of reactive oxygen species in response to environmental stress conditions, such as carvacrol.
authors.affiliation: LUNAM UniversitéAngers, France; INSERM U1066, Micro et Nanomédecines Biomimétiques, Institut de Biologie en Santé - Centre Hospitalier UniversitaireAngers, France.
authors.forename: Angélique
authors.initials: A
authors.lastname: Montagu
authors.affiliation: ATOMycA, INSERM Atip-Avenir Team, CRCNA, Inserm U892, 6299 CNRS, University of AngersAngers, France; Laboratoire de Bactériologie, Institut de Biologie en Santé - Centre Hospitalier UniversitaireAngers, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Joly-Guillou
authors.affiliation: Eydo Pharma Chartres, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Rossines
authors.affiliation: Plateforme d'Analyse Cellulaire Et Moléculaire, Institut de Biologie en Santé - Centre Hospitalier Universitaire Angers, France.
authors.forename: Jérome
authors.initials: J
authors.lastname: Cayon
authors.affiliation: ATOMycA, INSERM Atip-Avenir Team, CRCNA, Inserm U892, 6299 CNRS, University of AngersAngers, France; Laboratoire de Bactériologie, Institut de Biologie en Santé - Centre Hospitalier UniversitaireAngers, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Kempf
authors.affiliation: LUNAM UniversitéAngers, France; INSERM U1066, Micro et Nanomédecines Biomimétiques, Institut de Biologie en Santé - Centre Hospitalier UniversitaireAngers, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Saulnier
keywords: Acinetobacter baumannii; carvacrol; catalase; cinnamaldehyde; defense mechanisms; heat shock proteins; reactive oxygen species