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Due to the increasing occurrence and spread of antibiotic resistance pathogenic microorganisms, the development of antimicrobial materials has emerged as a strategy to control the bacterial activity and transmission. In this study, poly(vinyl alcohol)/silver nanoparticles-graphene oxide (PVA/AgNPs-GO) nanocomposites were synthesized by a one-step process with l -ascorbic acid as environmentally friendly reductant agent of a mixture of AgNO3, GO and PVA aqueous solutions. PVA/GO nanocomposites were also prepared for comparison. The structure, morphology, thermal, mechanical, water resistance and antibacterial properties of the samples were investigated as a function of GO and silver precursor contents. GO sheets decorated with spherical AgNPs were uniformly dispersed in the polymer matrix. The size range of most AgNPs was below 10 nm. Nanocomposites exhibited higher glass transition and crystallization temperatures. Thermal stability, mechanical and water resistance properties of PVA enhanced when GO was incorporated, and it was more remarkable in the presence of AgNPs-GO. PVA/AgNPs-GO nanocomposites showed antibacterial activity against Gram negative bacteria Escherichia coli and against Gram positive bacteria Staphylococcus aureus, being its efficiency dependent on exposure time and AgNPs precursor concentration. In contrast, PVA/GO films showed no activity against both bacteria over the GO loading range investigated. PVA/AgNPs-GO nanocomposites may be potential wound dressings.

Candida parapsilosis is a frequent cause of fungal bloodstream infections, especially in critically ill neonates or immunocompromised patients. Due to the formation of biofilms, the use of indwelling catheters and other medical devices increases the risk of infection and complicates treatment, as cells embedded in biofilms display reduced drug susceptibility. Therefore, biofilm formation may be a significant clinical parameter, guiding downstream therapeutic choices. Here, we phenotypically characterized 120 selected isolates out of a prospective collection of 215 clinical C. parapsilosis isolates, determining biofilm formation, major emerging colony morphotype, and antifungal drug susceptibility of the isolates and their biofilms. In our isolate set, increased biofilm formation capacity was independent of body site of isolation and not predictable using standard or modified European Committee on Antimicrobial Susceptibility Testing (EUCAST) drug susceptibility testing protocols. In contrast, biofilm formation was strongly correlated with the appearance of non-smooth colony morphotypes and invasiveness into agar plates. Our data suggest that the observation of non-smooth colony morphotypes in cultures of C. parapsilosis may help as an indicator to consider the initiation of anti-biofilm-active therapy, such as the switch from azole- to echinocandin- or polyene-based strategies, especially in case of infections by potent biofilm-forming strains. This work was funded in part by grants or scholarships from the ZabaldUz program (Universidad del País Vasco/Euskal Herriko Unibertsitatea) to IDlP, the Consejería de Educación, Universidades e Investigación (GIC15/78 IT-990-16) of Gobierno Vasco-Eusko Jaurlaritza to GQ, the Ministerio de Economía y Competitividad (grants SAF2013-47570-P and SAF2017-86188-P, the latter co-financed by FEDER) of the Spanish government to P.G. and G.Q., and the FP7-PEOPLE-2013-ITN—Marie-Curie Action: “Initial Training Networks”: Molecular Mechanisms of Human Fungal Pathogen Host Interaction, ImResFun, MC-ITN-606786, to O.B. and U.G.

Although Candida albicans remains the major etiological agent of invasive candidiasis, Candida glabrata and other emerging species of Candida are increasingly isolated. This species is the second most prevalent cause of candidiasis in many regions of the world. However, clinical isolates of Candida nivariensis and Candida bracarensis can be misidentified and are underdiagnosed due to phenotypic traits shared with C. glabrata. Little is known about the two cryptic species. Therefore, pathogenesis studies are needed to understand their virulence traits and their susceptibility to antifungal drugs. The susceptibility of Caenorhabditis elegans to different Candida species makes this nematode an excellent model for assessing host-fungus interactions. We evaluated the usefulness of C. elegans as a nonconventional host model to analyze the virulence of C. glabrata, C. nivariensis, and C. bracarensis. The three species caused candidiasis, and the highest virulence of C. glabrata was confirmed. Furthermore, we determined the efficacy of current antifungal drugs against the infection caused by these species in the C. elegans model. Amphotericin B and azoles showed the highest activity against C. glabrata and C. bracarensis infections, while echinocandins were more active for treating those caused by C. nivariensis. C. elegans proved to be a useful model system for assessing the pathogenicity of these closely related species.

Drug resistance of pathogenic microorganisms has become a global public health problem, which has prompted the development of new materials with antimicrobial properties. In this context, antimicrobial nanohybrids are an alternative due to their synergistic properties. In this study, we used an environmentally friendly one-step approach to synthesize graphene oxide (GO) decorated with silver nanoparticles (GO&ndash, AgNPs). By this process, spherical AgNPs of average size less than 4 nm homogeneously distributed on the surface of the partially reduced GO can be generated in the absence of any stabilizing agent, only with ascorbic acid (L-AA) as a reducing agent and AgNO3 as a metal precursor. The size of the AgNPs can be controlled by the AgNO3 concentration and temperature. Smaller AgNPs are obtained at lower concentrations of the silver precursor and lower temperatures. The antimicrobial properties of nanohybrids against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, Gram-positive Staphylococcus aureus, and the yeast Candida albicans were found to be concentration- and time-dependent. C. albicans and S. aureus showed the highest susceptibility to GO&ndash, AgNPs. These nanohybrids can be used as nanofillers in polymer nanocomposites to develop materials with antimicrobial activity for applications in different areas, and another potential application could be cancer therapeutic agents.

[EN] Background: Morphological, physical and chemical properties of both implants and prostheses can determine the biofilm formation on their surface and increase the risk of biological complications. The aim of this study was to evaluate the capacity of biofilm formation of Candida albicans on different materials used to manufacture abutments and prostheses. Material and Methods: Biofilm formation was analyzed on cp grade II titanium, cobalt-chromium alloy and zirconia, silicone, acrylic resin (polymethylmethacrylate) and nano-hybrid composite. Some samples were partially covered with lithium disilicate glass ceramic to study specifically the junction areas. C. albicans was incubated in a biofilm reactor at 37 °C with agitation. The biofilm formation was evaluated at 24 and 48 hours. In addition, the morphology of the biofilm was evaluated by scanning electron microscopy. Results: C. albicans developed biofilms on the surface of all materials tested. Cobalt-chromium alloy showed the lowest density of adhered biofilm, followed by zirconia and titanium. Silicone and resin showed up to 20 times higher density of biofilm. A higher biofilm formation was observed when junctions of materials presented micropores or imperfections. Conclusions: The biofilm formed in the three materials used in the manufacture of abutments and prostheses showed no major differences, being far less dense than in the resins. Two clinical recommendations can be made: to avoid the presence of resins in the subgingival area of implant prostheses and to design prostheses placing cobalt-chromium alloy/ceramic or titanium/ceramic junctions as far as possible from implants. ES, GQ, and EE have received research grant support from the Consejería de Educación, Universidades e Investigación del Gobierno Vasco-Eusko Jaurlaritza (GIC15 78 IT-990-16), the Ministerio de Economía y Competitividad del Gobierno de España, MINECO (SAF2017-86188-P) and the Universidad del País Vasco/Euskal Herriko Unibertsitatea, UPV/EHU (UFI 11/25). The authors report no conflicts of interest related to this study. The authors thank for technical and human support provided by Ramón Santamaría (Corus dental) and Analytical and High-Resolution Microscopy Service in Biomedicine of SGIker-UPV/EHU.

Most hospitalized patients are carriers of biomedical devices. Infections associated with these devices cause great morbidity and mortality, especially in patients in intensive care units. Numerous strategies have been designed to prevent biofilm development on biodevices. However, biofilm formation is a complex process not fully clarified. In the current study, roughness and hydrophobicity of different biomaterials was analyzed to assess their influences on the biofilm formation of four leading etiological causes of healthcare-associated infections, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Candida albicans, using a CDC biofilm reactor. Hydrophobic materials allowed the formation of more abundant and profuse biofilms. Roughness had effect on biofilm formation, but its influence was not significant when material hydrophobicity was considered.

EnglishCandidiasis is a mycotic infection caused by species of Candida genus. Candida albicans is the major aetiological agent, although other species of Candida, such as Candida glabrata, are considered emerging causes of this disease. The species, Candida bracarensis and Candida nivariensis, are phylogenetically similar to Candida glabrata and can be correctly differentiated by molecular techniques. These changes in the aetiology have serious implications for diagnosis, treatment and prognosis; considering that yeast pathogenesis or susceptibilities to current antifungal drugs may be different. Invertebrate models, such as the nematode Caenorhabditis elegans and the lepidopter Galleria mellonella, are an attractive alternative for the study of fungal pathogenesis and antifungal therapy. The aim of this research study was to evaluate the usefulness of these two non-convetional model to assess the in vivo virulence of the phylogenetically close-related species, Candida glabrata, Candida bracarensis and Candida nivariensis. euskaraKandidiasia Candida generoko espezieek eragindako infekzio mikotikoa da. Candida albicans agente etiologiko nagusia da baina gero eta gehiagotan Candida generoko beste espezie batzuk agertzen ari dira kandidiasiaren eragile bezala eta, hauen artean, Candida glabrata espeziea. Espezie honekin lotuta beste bi espezie daude, Candida bracarensis eta Candida nivariensis, teknika molekularrek ondo desberdindu ditzaketenak. Aldaketa etiologiko hauek ondorio larriak izan ditzakete kandidiasiaren diagnostikoan, tratamenduan edota pronostikoan, besteak beste, bere patogenia edo antifungikoekiko sentikortasuna oso desberdina izan daitezkeelako. Ordezko eredu esperimentalek erabiliz mikroorganismoek eragindako gaixotasunen patogenia eta terapia ezagutzeko ezinbesteko aukera ematen dizkigute, eta hauen artean, Caenorhabditis elegans nematodoa eta Galleria mellonella lepidopteroa ditugu. Ikerketa lan honetan konbentzionalak ez diren bi animalia eredu hauen erabilgarritasuna ebaluatu nahi izan da Candida glabrata, Candida bracarensis eta Candida nivariensis harreman filogenetiko estua duten hiru espezie hauen birulentzia in vivo aztertzeko.

The design of new materials with antimicrobial properties has emerged in response to the need for preventing and controlling the growth of pathogenic microorganisms without the use of antibiotics. In this study, partially reduced graphene oxide decorated with silver nanoparticles (GO&ndash, AgNPs) was incorporated as a reinforcing filler with antibacterial properties to poly(vinyl alcohol) (PVA) for preparation of poly(vinyl alcohol)/graphene oxide-silver nanoparticles nanocomposites (PVA/GO&ndash, AgNPs). AgNPs, spherical in shape and with an average size of 3.1 nm, were uniformly anchored on the partially reduced GO surface. PVA/GO&ndash, AgNPs nanocomposites showed exfoliated structures with improved thermal stability, tensile properties and water resistance compared to neat PVA. The glass transition and crystallization temperatures of the polymer matrix increased with the incorporation of the hybrid. The nanocomposites displayed antibacterial activity against Staphylococcus aureus and Escherichia coli in a filler content- and time-dependent manner. S. aureus showed higher susceptibility to PVA/GO&ndash, AgNPs films than E. coli. Inhibitory activity was higher when bacterial cells were in contact with nanocomposite films than when in contact with leachates coming out of the films. GO&ndash, AgNPs based PVA nanocomposites could find application as wound dressings for wound healing and infection prevention.

Invasive candidiasis is caused mainly by Candida albicans, but other Candida species have increasing etiologies. These species show different virulence and susceptibility levels to antifungal drugs. The aims of this study were to evaluate the usefulness of the non-conventional model Caenorhabditis elegans to assess the in vivo virulence of seven different Candida species and to compare the virulence in vivo with the in vitro production of proteinases and phospholipases, hemolytic activity and biofilm development capacity. One culture collection strain of each of seven Candida species (C. albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida metapsilosis, Candida orthopsilosis and Candida parapsilosis) was studied. A double mutant C. elegans AU37 strain (glp-4;sek-1) was infected with Candida by ingestion, and the analysis of nematode survival was performed in liquid medium every 24 h until 120 h. Candida establishes a persistent lethal infection in the C. elegans intestinal tract. C. albicans and C. krusei were the most pathogenic species, whereas C. dubliniensis infection showed the lowest mortality. C. albicans was the only species with phospholipase activity, was the greatest producer of aspartyl proteinase and had a higher hemolytic activity. C. albicans and C. krusei caused higher mortality than the rest of the Candida species studied in the C. elegans model of candidiasis.