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The antibacterial and anti-inflammatory potential of natural, plant-derived compounds has been reported in many studies. Emerging evidence indicates that plant-derived essential oils and/or their major compounds may represent a plausible alternative treatment for acne, a prevalent skin disorder in both adolescent and adult populations. Therefore, the purpose of this study was to develop and subsequently analyze the antimicrobial activity of a new multi-agent, synergic formulation based on plant-derived antimicrobial compounds (i.e., eugenol, β-pinene, eucalyptol, and limonene) and anti-inflammatory agents for potential use in the topical treatment of acne and other skin infections. The optimal antimicrobial combinations selected in this study were eugenol/β-pinene/salicylic acid and eugenol/β-pinene/2-phenoxyethanol/potassium sorbate. The possible mechanisms of action revealed by flow cytometry were cellular permeabilization and inhibition of efflux pumps activity induced by concentrations corresponding to sub-minimal inhibitory (sub-MIC) values. The most active antimicrobial combination represented by salycilic acid/eugenol/β-pinene/2-phenoxyethanol/potassium sorbate was included in a cream base, which demonstrated thermodynamic stability and optimum microbiological characteristics., Competing Interests: The authors declare no conflict of interest.

Undesired biofilm development is a major concern in many areas, especially in the medical field. The purpose of the present study was to comparatively investigate the antibiofilm efficacy of usnic acid, in soluble versus nanofluid formulation, in order to highlight the potential use of Fe(3) O(4)/oleic acid (FeOA) nanofluid as potential controlled release vehicle of this antibiofilm agent. The (+) -UA loaded into nanofluid exhibited an improved antibiofilm effect on S. aureus biofilm formation, revealed by the drastic decrease of the viable cell counts as well as by confocal laser scanning microscopy images. Our results demonstrate that FeOA nanoparticles could be used as successful coating agents for obtaining antibiofilm pellicles on different medical devices, opening a new perspective for obtaining new antimicrobial and antibiofilm surfaces, based on hybrid functionalized nanostructured biomaterials.

The aim of this study was to assess the antibacterial and antifungal potential of some Romanian medicinal plants, arnica--Arnica montana, wormwood--Artemisia absinthium and nettle--Urtica dioica. In order to perform this antimicrobial screening, we obtained the vegetal extracts and we tested them on a series of Gram-positive and Gram-negative bacteria, and also against two fungal strains. The vegetal extracts showed antimicrobial activity preferentially directed against the planktonic fungal and bacterial growth, while the effect against biofilm formation and development was demonstrated only against S. aureus and C. albicans. Our in vitro assays indicate that the studied plant extracts are a significant source of natural alternatives to antimicrobial therapy, thus avoiding antibiotic therapy, the use of which has become excessive in recent years.

The vegetal extracts are used as an ecological alternative to classical anti-infectious treatments based on antibiotics, exhibiting the advantage of reduced secondary effects. Most of these compounds are secondary metabolites, especially aromatic substances synthesized by plants in a reduced concentration. The aim of this study was to investigate the influence of usnic acid against quorum sensing and response mechanisms involved in the initiation and development of the dental plaque biofilm and its tolerance to antimicrobials. Three samples of super-gingival dental plaque were treated for different time intervals with usnic acid at 200 ig/ml in dimethyl-sulfoxide, representing the MIC value. Each dental plaque sample was inoculated in Brain Heart Infusion medium to establish the microbial growing curve by viable cells counts using the tenfold microdilutions method. For strains identification there were used the microtest galleries: API 20Strep, API Staph, API 20NE, API 20E. MIC value for usnic acid was determined by twofold microdilution technique. Usnic acid selectively inhibited the biofilm development by Gram positive bacteria and the expression of haemolytic properties of strains isolated from the dental plaque. The growth curve of the isolated strains was affected by usnic acid, the changes consisting of the lag phase extension to 6-10 h (this time interval being considered as the persistence time of antimicrobial activity) and the significant decrease of the viable cell number and consecutively, the prolongation of the generation time. These effects are demonstrating the interference of the usnic acid with the intra- and interspecies signalling mechanisms based on quorum sensing and response and dependent on cell density, giving the possibility to use them as an active principle in some new pharmaceutical formula intended for the prevention and treatment of gingival and periodontal pathologies.

The microfungi and especially the opportunistic yeasts have emerged as a major cause of human diseases, particularly among immunocompromised individuals and hospitalized patients. Nowadays, medical devices became an essential component in the supportive care of many patients and the association of microbial biofilm related infections with indwelling devices are of great interest. The treatment of fungal infections has lagged behind antibacterial chemotherapy, reason for which the development of alternative or complementary therapeutic strategies become an emergency. The essential oils are proven to exhibit a strong antimicrobial effect on biofilm grown cells, but because of the unstable compounds existing in the complex matrix of the essential oils, the stabilization processes is an important matter. The aim of the present study was to investigate the utility of a new hybrid nanosystem covering treatment for the stabilization of the essential oils and for the further improvement of their antifungal properties. Nanoparticles obtained by a modified Massart method were used in order to obtain a core/shell/coated-shell for the covering treatment of inert substrata, subsequently used for the in vitro study of the fungal biofilm development. The biofilm architecture was assessed by confocal laser scanning microscopy. The results are recommending the nanosystem for the stabilization of Anethum graveolens essential oils, which proved a significant antibiofilm activity, highlighting the opportunity of using them for the developing of efficient antimicrobial strategies for microbial biofilms related infections. [ABSTRACT FROM AUTHOR]