494 research outputs found
Emerging strategies for environmental decontamination of the nosocomial fungal pathogen Candida auris
In vitro method to study antifungal perfusion in Candida Biofilms
Antimycotic perfusion through Candida biofilms was demonstrated by a modification of a simple in vitro diffusion cell bioassay system. Using this model, the perfusion of three commonly used antifungal agents, amphotericin B, fluconazole, and flucytosine, was investigated in biofilms of three different Candida species (i.e., Candida albicans, Candida parapsilosis, and Candida krusei) that were developed on microporous filters. Scanning electron microscopy revealed that C. albicans formed a contiguous biofilm with tightly packed blastospores and occasional hyphae compared with C. parapsilosis and C. krusei, which developed confluent biofilms displaying structural heterogeneity and a lesser cell density, after 48 h of incubation on nutrient agar. Minor structural changes were also perceptible on the superficial layers of the biofilm after antifungal perfusion. The transport of antifungals to the distal biofilm-substratum interface was most impeded by C. albicans biofilms in comparison to C. parapsilosis and C. krusei. Fluconazole and flucytosine demonstrated similar levels of perfusion, while amphotericin B was the least penetrant through all three biofilms, although the latter appeared to cause the most structural damage to the superficial cells of the biofilm compared with the other antifungals. These results suggest that the antifungal perfusion through biofilm mode of growth in Candida is dependent both on the antimycotic and the Candida species in question, and in clinical terms, these phenomena could contribute to the failure of Candida biofilm-associated infections. Finally, the in vitro model we have described should serve as a useful system to investigate the complex interactions that appear to operate in vivo within the biofilm-antifungal interphase.published_or_final_versio
The role of saliva and serum in Candida albicans biofilm formation on denture acrylic surfaces
The long term effect of either a salivary or a serum pellicle on Candida albicans biofilm formation on denture acrylic surfaces was investigated both by quantifying the ATP (adenosine triphosphate) content of the resultant biofilms and by scanning electron microscopy. When the biofilm formation on saliva-coated acrylic strips was examined, the yeasts initially colonised this surface at a slower rate than the controls although with increasing incubation time, at 72 h, the ATP content was almost ten-fold higher than the protein-free control strips. Ultrastructural studies revealed this to be due to cell aggregation and hyphal emergence, phenomena not observed in the controls. As compared with the control strips, biofilm activity of the serum-coated strips was almost 100-fold greater within 48 h incubation, and scanning electron microscopy revealed multilayer blastospore-blastospore co-adhesion, germ tube, hyphal and pseudohyphal emergence and blastospore-hyphal coadherence. Further immunocytochemical observation revealed that concanavalin-A binding material and fibronectin were involved in biofilm formation on both saliva and serum coated specimens and, in addition, mannan-binding protein and protein-A binding material also contributed to the biofilm formation on serum coated specimens.link_to_OA_fulltex
The Role of Saliva and Serum in Candida albicans Biofilm Formation on Denture Acrylic Surfaces
The Polonnaruwa meteorite: oxygen isotope, crystalline and biological composition
Results of X-Ray Diffraction (XRD) analysis, Triple Oxygen Isotope analysis
and Scanning Electron Microscopic (SEM) studies are presented for stone
fragments recovered from the North Central Province of Sri Lanka following a
witnessed fireball event on 29 December 2012. The existence of numerous
nitrogen depleted highly carbonaceous fossilized biological structures fused
into the rock matrix is inconsistent with recent terrestrial contamination.
Oxygen isotope results compare well with those of CI and CI-like chondrites but
are inconsistent with the fulgurite hypothesis.Comment: 7 pages, 7 figures, 4 table
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