Search

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]

This study aimed to establish the essential oil (EO) composition from young shoots of Picea abies , Larix decidua , Pseudotsuga menziesii , and Pinus nigra harvested from Romania and evaluate their antimicrobial and anti-virulence activity, as well as potential synergies with currently used antibiotics. The samples' EO average content varied between 0.62% and 1.02% (mL/100 g plant). The mono- and sesquiterpene hydrocarbons were dominant in the composition of the studied EOs. The antimicrobial activity revealed that the minimum inhibitory concentration (MIC) values for the tested EOs and some pure compounds known for their antimicrobial activity ranged from 6.25 to 100 µL/mL. The most intensive antimicrobial effect was obtained for the Pinus nigra EO, which exhibited the best synergistic effect with some antibiotics against Staphylococcus aureus strains (i.e., oxacillin, tetracycline, erythromycin and gentamycin). The subinhibitory concentrations (sMIC) of the coniferous EOs inhibited the expression of soluble virulence factors (DN-ase, lipase, lecithinase, hemolysins, caseinase and siderophore-like), their efficiency being similar to that of the tested pure compounds, and inhibited the rhl gene expression in Pseudomonas aeruginosa , suggesting their virulence-arresting drug potential.

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.

A family of distinct ZnO morphologies - hollow, compartmented, core-shell and full solid ZnO spheres, dispersed or interconnected - is obtained by a simple hydrothermal route, in the presence of the starch biopolymer. The zinc-carbonaceous precursors were characterized by infrared spectroscopy, thermal analysis and scanning electron microscopy, while the ZnO spheres, obtained after the thermal processing, were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, UV-VIS spectroscopy, photoluminescence measurements, antimicrobial, anti-biofilm and flow cytometry tests. The formation mechanism proposed for this versatile synthesis route is based on the gelling ability of amylose, one of the starch template constituents, responsible for the effective embedding of zinc cations into starch prior to its hydrothermal carbonization. The simple variation of the raw materials concentration dictates the type of ZnO spheres. The micro-sized ZnO spheres exhibit high antibacterial and anti-biofilm activity against Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) reference and methicillin resistant clinical strains especially for Gram-negative biofilms (P. aeruginosa), demonstrating great potential for new ZnO anti-biofilm formulations., (Copyright © 2015 Elsevier Inc. All rights reserved.)

During the present study, we have evaluated magnetic chitosan as a potential drug delivery device, by specifically determining if chitosan could elute antibiotics in an active form that would be efficacious in inhibiting Staphylococcus aureus and Escherichia coli growth. We have demonstrated that the incorporation of cephalosporins of second, third and fourth generation into magnetic chitosan microspheres can possibly lead to an improved delivery of antibiotics in active forms, probably due to the inherent properties of chitosan., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The purpose of this study was to design a new nanosystem for catheter surface functionalization with an improved resistance to Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853 colonization and subsequent biofilm development. New 2-((4 ethylphenoxy)methyl)-N-(substituted-phenylcarbamothioyl)-benzamides were synthesized and used for coating a core/shell nanostructure. Their chemical structures were elucidated by NMR, IR and elemental analysis, being in agreement with the proposed ones. Fe(3)O(4)/C(12 )of up to 5 nm size had been synthesized with lauric acid as a coating agent and characterized by XRD, FT-IR, TGA, TEM and biological assays. The catheter pieces were coated with the fabricated nanofluid in magnetic field. The microbial adherence ability was investigated in 6 multiwell plates by using culture based methods and Scanning Electron Microscopy (SEM). The nanoparticles coated with the obtained compounds 1a-c inhibited the adherence and biofilm development ability of the S. aureus and P. aeruginosa tested strains on the catheter functionalized surface, as shown by the reduction of viable cell counts and SEM examination of the biofilm architecture. Using the novel core/shell/adsorption-shell to inhibit the microbial adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with improved anti-biofilm properties.

The purpose of this work was to investigate the potential of functionalized magnetite nanoparticles to improve the antibiofilm properties of textile dressing, tested in vitro against monospecific Candida albicans biofilms. Functionalized magnetite (Fe3O4/C18), with an average size not exceeding 20 nm, has been synthesized by precipitation of ferric and ferrous salts in aqueous solution of oleic acid (C18) and NaOH. Transmission electron microscopy, X-ray diffraction analysis, and differential thermal analysis coupled with thermo gravimetric analysis were used as characterization methods for the synthesized Fe3O4/C18. Scanning electron microscopy was used to study the architecture of the fungal biofilm developed on the functionalized textile dressing samples and culture-based methods for the quantitative assay of the biofilm-embedded yeast cells. The optimized textile dressing samples proved to be more resistant to C. albicans colonization, as compared to the uncoated ones; these functionalized surfaces-based approaches are very useful in the prevention of wound microbial contamination and subsequent biofilm development on viable tissues or implanted devices.

Biofilms formed by fungal organisms are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence of the fungi despite antifungal therapy. The purpose of this study is to combine the unique properties of nanoparticles with the antimicrobial activity of the Rosmarinus officinalis essential oil in order to obtain a nanobiosystem that could be pelliculised on the surface of catheter pieces, in order to obtain an improved resistance to microbial colonization and biofilm development by Candida albicans and C. tropicalis clinical strains. The R. officinalis essential oils were extracted in a Neo-Clevenger type apparatus, and its chemical composition was settled by GC-MS analysis. Functionalized magnetite nanoparticles of up to 20 nm size had been synthesized by precipitation method adapted for microwave conditions, with oleic acid as surfactant. The catheter pieces were coated with suspended core/shell nanoparticles (Fe3O4/oleic acid:CHCl3), by applying a magnetic field on nanofluid, while the CHCl3 diluted essential oil was applied by adsorption in a secondary covering treatment. The fungal adherence ability was investigated in six multiwell plates, in which there have been placed catheters pieces with and without hybrid nanoparticles/essential oil nanobiosystem pellicle, by using culture-based methods and confocal laser scanning microscopy (CLSM). The R. officinalis essential oil coated nanoparticles strongly inhibited the adherence ability and biofilm development of the C. albicans and C. tropicalis tested strains to the catheter surface, as shown by viable cell counts and CLSM examination. Due to the important implications of Candida spp. in human pathogenesis, especially in prosthetic devices related infections and the emergence of antifungal tolerance/resistance, using the new core/shell/coated shell based on essential oil of R. officinalis to inhibit the fungal adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with antibiofilm properties.

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 aim of present study was to investigate the microbial colonization of worn contact lenses (CLs) and to evaluate the inhibitory effect of pomelo (Citrus maxima) peels essential oil on the biofilm development on unworn CLs. The essential oil was isolated by steam distillation and analyzed by gas chromatography coupled with mass spectrometry, twenty compounds being isolated. The antimicrobial activity of pomelo oil was tested against S. epidermidis and P. aeruginosa strains, known for their ability to develop biofilms on prosthetic devices, by qualitative screening methods and quantitative assay of the minimal inhibitory concentrations (MIC) in order to evaluate the antibiofilm activity. Our study revealed that all worn CLs where 100% colonized by staphylococci and Enterobacteriaceae strains. The pomelo essential oil inhibited the development of bacterial biofilms formed by Gram-positive and Gram-negative microorganisms on soft CLs, its antibiofilm activity being specific and dependent on different physical parameters (contact time and temperature). The architecture of bacterial biofilms developed on soft contact lenses was analyzed using confocal scanning laser microscopy (CSLM).

Regulatory constraints and environmental and human health concerns have promoted the search for alternative bio-control strategies of fire blight, a destructive disease of rosaceous plants which produces serious losses in apple and pear orchards all over the world. The aim of this study was to establish the antimicrobial activity of Citrus maxima essential oil against Erwinia amylovora. An agar diffusion method was used for the screening of the inhibitory effect of Citrus maxima essential oil on bacterial strains growth. The quantitative inhibitory effect of pomelo oil on in vitro biofilm development was established by a microtiter colorimetric assay. In order to investigate the ability of pomelo oil to interfere with bacterial adherence and subsequent biofilm development on leaves obtained from different pomaceous fruit trees species and cultivars: Pyrus (Napoca, Williams), Malus (Golden Delicious) and Cydonia (Aromate), leaves were immersed in pomelo oil for 1, 2, 3, 5 and 10 minutes before exposing them to bacterial colonization. The architecture of bacterial biofilms developed on leaf surface was analyzed using Confocal Scanning Laser Microscopy (CSLM). Our results showed that Citrus maxima essential oil inhibited the development of bacterial biofilms on leaves, pomelo oil being more active on Cydonia (Aromate) leaves when the leaves were treated for 5 minutes. The results obtained from this study may contribute to the development of new bio-control agents as alternative strategies to protect fruit trees from fire blight disease.

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.