Stress Conditions Induced by Carvacrol and Cinnamaldehyde on Acinetobacter baumannii

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

Étude de la sensibilité de 224 bactéries isolées d’infections hospitalières vis-à-vis des composés JCA 250 et JCA 251 à base d’huiles essentielles issus de la recherche Aroma Technologies

But de l’étudeIl a été de déterminer le spectre antibactérien de JCA 250 et JCA 251, deux substances d’origine naturelle issues de la recherche Aroma Technologies, sur une population bactérienne provenant d’infections cliniques. Méthode Deux cent vingt-quatre souches bactériennes ont été testées. Les concentrations minimales inhibitrices (CMI) des composés JCA 250 et JCA 251 ont été déterminées par la méthode en milieu gélosé. Les tests ont été réalisés en triple. Résultats La valeur moyenne des CMI était de 0,20 % pour JCA 250 et de 0,15 % pour JCA 251. JCA 251 présentait régulièrement une meilleure activité. Toutes les entérobactéries étaient inhibées à des concentrations inférieures ou égales à 0,15 % pour JCA 250 ou 251. Pour les aérobies stricts, les valeurs des CMI étaient plus étalées. Deux souches de Pseudomonas aeruginosa se distinguaient de la population avec des CMI de JCA 251 de 0,25 % et 0,40 %. Chez les cocci à Gram positif, les souches bactériennes étaient toutes inhibées par des concentrations inférieures ou égales à 0,25 %. Les populations les plus résistantes étaient les entérocoques et les lactobacilles, avec des CMI supérieures ou égales à 0,20 % vis-à-vis de JCA 250 et JCA 251. Les anaérobies présentaient des CMI très voisines pour un groupe bactérien hétérogène. Une souche de Propionibacterium sp. se détachait du groupe et était inhibée à des concentrations de 0,5 %. Conclusion L’ensemble des résultats ont montré une activité antibactérienne intéressante sur les bactéries isolées de prélèvements cliniques. La plupart des souches étaient inhibées par des concentrations de 0,2 %. Les valeurs moyennes les plus élevées étaient obtenues avec des bactéries commensales de la flore, ce qui est un aspect particulièrement intéressant à exploiter dans cette étude

Synergistic interactions between doxycycline and terpenic components of essential oils encapsulated within lipid nanocapsules against gram negative bacteria

The combination of essential oils (EOs) with antibiotics provides a promising strategy towards combating resistant bacteria. We have selected a mixture of 3 major components extracted from EOs: carvacrol (oregano oil), eugenol (clove oil) and cinnamaldehyde (cinnamon oil). These compounds were successfully encapsulated within lipid nanocapsules (LNCs). The EOs-loaded LNCs were characterised by a noticeably high drug loading of 20% and a very small particle diameter of 114nm. The in vitro interactions between EOs-loaded LNCs and doxycycline were examined via checkerboard titration and time-kill assay against 5 Gram-negative strains: Acinetobacter baumannii SAN, A. baumannii RCH, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa. No growth inhibition interactions were found between EOs-loaded LNCs and doxycycline (FIC index between 0.7 and 1.30). However, when bactericidal effects were considered, a synergistic interaction was observed (FBC index equal to 0.5) against all tested strains. A synergistic effect was also observed in time-kill assay (a difference of at least 3 log between the combination and the most active agent alone). Scanning electron microscopy (SEM) was used to visualise the changes in the bacterial membrane. The holes in bacterial envelope and leakage of cellular contents were observed in SE micrographs after exposure to the EOs-LNCs and the doxycycline combination

Nanocapsulation of essential oils for preventing or curing infectious diseases alone or with antibiotic

A composition, an encapsulated composition and/or nanoparticles comprising at least one essential oil having a large spectrum antibacterial, antiparasitic, antifungal activity and/or a plant antipathogen, optionally at least one antibiotic and optionally a pharmaceutically acceptable carrier is disclosed. Methods for treating infectious diseases and especially bacterial, parasitic, fungal and/or plant infectious by using this composition, encapsulated composition and/or nanoparticles are also disclosed

Prevention of Bacterial Infections Using Encapsulated Phytophenolic Actives

The recent overuse of antibiotics has led to the emergence of multidrug-resistant bacteria (MRB) responsible for severe infections, which are often difficult or impossible to treat. In the world of infectious diseases, the lack of development ofnew antibacterial molecules by the pharmaceutical industry is a major problem. Today, the number of new drugs able totreat Gram-negative MRB infections is significantly limited. It is therefore important to find new therapeutic approaches that are effective but limit the emergence of bacterial resistance. Medicinal plants containing essential oils constitute a potentially large source of antibacterial molecules that can be used to treat MRB infections. Essential oils, which primarily consist of phenolic compounds, have been demonstrated to have antibacterial effects against a wide variety of microorganisms. However, these molecules exhibit poor solubility in water and are biologically unstable. In addition, these molecules tend to bind to food constituents, resulting in decreased bioavailability and antimicrobial activity. To overcome these challenges, essential oils can be encapsulated within nanoparticles to enhance their solubility in aqueous media and to increase their antibacterial activity by facilitating contact with bacterial cells. The high antibacterial effectiveness of several delivery systems, including emulsions, liposomes and nanoparticles, indicates the potential of encapsulated phenols. The anti-infective potential of essential oils, combined with various technologies from nanomedicine, provides a new hope in the fight against infectious diseases

Aromatic and Terpenic Compounds Loaded in Lipidic Nanocapsules: Activity against Multi-drug Resistant Acinetobacter baumannii Assessed in vitro and in a Murine Model of Sepsis.

Given the spread of multidrug resistance and the number of antibiotics in development, finding new antibacterial strategies becomes necessary. One of these strategies is to use extracts of essential oils that are a potential reservoir of effective antibacterial molecules. The objective of the study was to evaluate the possibility of administering to animal, mixtures of carvacrol and eugenol (phenols), cinnamaldehyde (aldehyde) and/or β-caryophyllene (alkene) encapsulated in lipid nanocapsules to provide an optimal bio distribution and antimicrobial efficacy. These suspensions were tested in vitro and the results showed an important antibacterial activity against A. baumannii, a multidrugresistant microorganism responsible for outbreaks in intensive care units, similar to the activity of non-encapsulated mixtures. Subsequently, the suspensions activities were assessed with a murine model of sepsis using the same A.Baumannii strain. These preliminary results showed a mice survival varying from 45% to 55%. It is the first time that antimicrobial essential oils can be administered intraperitonneally via nanomedicine. These results are encouraging and further studies are needed to pursue the development of this strategy