Yeast Adhesion Research Articles

Investigation of adhesion status of Candida species to the surface of resin materials produced at different angles with additive manufacturing

BackgroundThe aim of this study was to evaluate the adhesion of Candida glabrata, Candida albicans, Candida krusei, Candida parapsilosis and Candida tropicalis yeasts to disk-shaped resin materials produced from resin which used in the production of surgical guide with 0, 45 and 90-degrees printing orientations by Liquid Crystal Display additive manufacturing technology.MethodsDisk-shaped specimens were printed with surgical guide resin using the Liquid Crystal Display production technique in 3 printing orientations (0, 45 and 90-degrees). Surface roughness and contact angle values were evaluated. Real-Time PCR analysis was performed to evaluate Candida adhesion (C. glabrata, C. albicans, C. krusei, C. parapsilosis and C. tropicalis) Field emission scanning electron microscope (FESEM) images of the materials were obtained.ResultsSpecimens oriented at 45-degrees demonstrated higher surface roughness (P < .05) and lower contact angle values than other groups. No significant difference was found in the adhesion of C. glabrata, C. albicans, and C. parapsilosis among specimens printed at 0, 45, and 90-degrees orientations (P > .05). A higher proportion of C. krusei and C. tropicalis was found in the specimens printed at orientation degrees of 45 = 90 < 0 with statistical significance. Analyzing the adhesion of all Candida species reveals no statistical disparity among the printing orientations.ConclusionsThe surface roughness, contact angle, and adhesion of certain Candida species are affected by printing orientations. Hence, careful consideration of the printing orientation is crucial for fabricating products with desirable properties. In 45-degree production, roughness increases due to the layered production forming steps, whereas in 0-degree production, certain Candida species exhibit high adhesion due to the formation of porous structures. Consequently, considering these factors, it is advisable to opt for production at 90-degrees, while also considering other anticipated characteristics.

Adherence of Candida albicans to fibrin-clot matrices in a rat model for type 2 diabetes

Individuals with type 2 diabetes are at increased risk for the development of infective endocarditis and septic thrombosis. Adherence to fibrin clot matrices by Candida albicans is the initial step in initiation of the infective processes. Clots made from lean (Fa/fa) and obese (fa/fa) Zucker rat plasma were used to measure adherence of yeast grown at environmental temperature and human body temperature. Adherence to clots by C. albicans was influenced both by source of plasma and temperature of yeast growth. Amphotericin B was effective in diminishing the candidal binding to lean but not obese clots. The degree of fungal surface hydrophobicity did not correlate with adherence to clots. However, Candida adherence to clots from both lean and obese Zucker rats was inhibited by the pretreatment of cells with mannose. These findings indicate that treatment of thrombi-associated candidal infections with ergosterol-targeting drugs e.g., amphotericin B alone in hypercholesterolemic individuals may have decreased clinically efficacy.

Is Silver Addition to Scaffolds Based on Polycaprolactone Blended with Calcium Phosphates Able to Inhibit Candida albicans and Candida auris Adhesion and Biofilm Formation?

Candida spp. periprosthetic joint infections are rare but difficult-to-treat events, with a slow onset, unspecific symptoms or signs, and a significant relapse risk. Treatment with antifungals meets with little success, whereas prosthesis removal improves the outcome. In fact, Candida spp. adhere to orthopedic devices and grow forming biofilms that contribute to the persistence of this infection and relapse, and there is insufficient evidence that the use of antifungals has additional benefits for anti-biofilm activity. To date, studies on the direct antifungal activity of silver against Candida spp. are still scanty. Additionally, polycaprolactone (PCL), either pure or blended with calcium phosphate, could be a good candidate for the design of 3D scaffolds as engineered bone graft substitutes. Thus, the present research aimed to assess the antifungal and anti-biofilm activity of PCL-based constructs by the addition of antimicrobials, for instance, silver, against C. albicans and C. auris. The appearance of an inhibition halo around silver-functionalized PCL scaffolds for both C. albicans and C. auris was revealed, and a significant decrease in both adherent and planktonic yeasts further demonstrated the release of Ag+ from the 3D constructs. Due to the combined antifungal, osteoproliferative, and biodegradable properties, PCL-based 3D scaffolds enriched with silver showed good potential for bone tissue engineering and offer a promising strategy as an ideal anti-adhesive and anti-biofilm tool for the reduction in prosthetic joints of infections caused by Candida spp. by using antimicrobial molecule-targeted delivery.

Photodynamic inactivation of different Candida species and inhibition of biofilm formation induced by water-soluble porphyrins

Background: Candida spp. is the main fungal genus related to infections in humans, and its treatment has become a challenge due to the production of biofilm and its resistance/multi-resistance profile to conventional antifungals. Antimicrobial photodynamic therapy stands out as a treatment characterized by a broad spectrum of antimicrobial action, being able to induce oxidative stress in pathogens, and porphyrins are photosensitizers with high selectivity to pathogens. Thus, this work aimed to analyze the photoinactivation of different species of Candida by two cationic (4-H2TMeP+ and 3-H2TMeP+) and one anionic (4-H2TPSP‒) porphyrins. Materials and Methods: Microdilution assays were performed to determine the MIC100, with subsequent determination of MFC100. Determination of oxidative species was done through the use of scavengers, while biofilm morphological features were investigated using the atomic force microscopy. Results: Cationic porphyrins were significantly efficient in inactivating Candida albicans and non-albicans species with 100% growth inhibition and fungicidal activity (MFC100/MIC100 ≤ 4.0). The cationic porphyrins were also able to interfere in Candida spp biofilm formation. The photo-oxidative mechanism activated by 3-H2TMeP+ in Candida spp. is concurrent with the production of singlet oxygen and oxygen radical species. In the AFM analysis, 3-H2TMeP+ was able to reduce yeast adhesion to the surface. Conclusions: Cationic porphyrins can photo-inactivate different species of Candida in both planktonic and biofilm-associated forms, and reduce the adhesion of these fungi to the surface.

Adhesion of Yeast and Bacteria to Oral Surfaces.

Colonization of surfaces in the human body by microorganisms is an early, essential, step in the initiation of infectious disease. We have developed in vitro assays to investigate interactions between yeast or bacterial cells and human tissues, fluids, or prostheses. Such assays can be used to identify the adhesins, ligands, and receptors involved in these interactions, for example, by determining which components of the microbe or human tissue/fluid interfere with adherence in the assay. The assays can also be applied to find ways of preventing adhesion, and subsequent disease, by investigating the effects of different conditions and added compounds on adherence in the in vitro assays. Here we describe assays for measuring adhesion of the oral yeast Candida albicans, a common commensal and opportunistic pathogen, or the bacterium Staphylococcus epidermidis, which is not normally pathogenic but is known to form biofilms on medical prostheses. The assays described belong to two approaches to investigating adhesion and biofilm formation: (i) retention at a fixed time point following liquid washes, and (ii) retention against a continuous flow of medium.

Adherencia in vitro de Candida albicans en tres diferentes acondicionadores de tejidos usados en prostodoncia total

Antecedentes: Los acondicionadores de tejidos, son materiales utilizados en la superficie de la base de la dentadura por un tiempo de 4-7 días. Presentan en su superficie irregularidades y con un uso inadecuado, existe la adherencia de microorganismos como Candida albicans provocando Candidiasis Bucal. Objetivo: Cuantificar y analizar los tres acondicionadores de tejidos por medio de un Microscopio Óptico (MO) y de un Microscopio Electrónico de Barrido (MEB), en tres tiempos de inoculación. Estudio: Se elaboraron 36 muestras de inoculando Candida albicans in vitro durante 24, 72 y 168 hrs; se observaron mediante MO y MEB de donde se obtuvieron fotografías a un aumento de 500x, 2,000x y 5,000x. Resultados: El acondicionador de tejidos Coe Comfort presentó superficie regular con adhesión de levaduras en gemación e hifa, Lynal presentó superficie agrietada de 3 µm a 72 y 168 hrs con levaduras en gemación y Flexacryl presentó superficie agrietada a 72 y 168 hrs de 4 µm y una gran cantidad de levaduras en gemación. Conclusiones: El acondicionador Coe Comfort presenta una superficie más regular y con menor adhesión de Candida albicans, mientras que el acondicionador Flexacryl es el que presenta mayores irregularidades y adherencia de Candida albicans en su superficie.

Electrochemical Sensor Based on Biomass Yeast Integrated Sulfur‐doped Graphene and Carboxylated Carbon Nanotubes/MoS2 for Highly‐sensitive Detection of Pb2+

AbstractGlassy carbon electrodes (GCEs) modified with sulfur‐doped graphene (SG)/carboxylated carbon nanotube (CNT−COOH)/MoS2/yeast composite were prepared for electrochemical detection for lead ions by the simple hydrothermal methods and ultrasonic methods. The combination of SG and CNT−COOH could form a double‐layer carbon structure, providing more active detection sites for detection for lead, which could also contribute to adherence of yeast and MoS2. The SG/CNT−COOH/MoS2/yeast exhibited a high response in detecting low concentrations of lead ions. And then the SG/CNT−COOH/MoS2/yeast was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), Transmission electron microscope (TEM), Scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). Compared with traditional detection technology, the linear range of the sensor was 10−6∼10−14 g/L. And the lower of detection (LOD) down to 2.61×10−15 g/L was achieved. The sensor showed prospective applications in detection of Pb2+ in real serum samples.

Biochemical features and early adhesion of marine Candida parapsilosis strains on high-density polyethylene.

Plastic debris are constantly released into oceans where, due to weathering processes, they suffer fragmentation into micro- and nanoplastics. Diverse microbes often colonize these persisting fragments, contributing to their degradation. However, there are scarce reports regarding the biofilm formation of eukaryotic decomposing microorganisms on plastics. Here, we evaluated five yeast isolates from deep-sea sediment for catabolic properties and early adhesion ability on high-density polyethylene (HDPE). We assessed yeast catabolic features and adhesion ability on HDPE fragments subjected to abiotic weathering. Adhered cells were evaluated through Crystal Violet Assay, Scanning Electron Microscopy, Atomic Force Microscopy and Infrared Spectroscopy. Isolates were identified as Candida parapsilosis and exhibited wide catabolic capacity. Two isolates showed high adhesion ability on HDPE, consistently higher than the reference C. parapsilosis strain, despite an increase in fragment roughness due to weathering. Isolate Y5 displayed the most efficient colonization, with production of polysaccharides and lipids after 48h of incubation. This work provides insights on catabolic metabolism and initial yeast-HDPE interactions of marine C. parapsilosis strains. Our findings represent an essential contribution to the characterization of early interactions between deep-sea undescribed yeast strains and plastic pollutants found in oceans.

Evaluation of the genotoxic and mutagenic potentials of homeopathic Candida albicans solutions

Background: Candida spp is naturally found in humans’ flora of skin, gastrointestinal and genitourinary tracts and, in general, up to 75% of the population does not have any symptom [1]. However, oral candidiasis is very common among HIV patients and patients undergoing chemotherapy. The treatment of oral candidiasis is necessary once the disease causes discomfort and dysphagia, resulting in poor nutrition, slow recovery, and prolonged hospital stay [2,3]. Preliminary results obtained by our group with a new biotherapic prepared from Candida albicans (Candida 30x) showed a great potential to reduce the candida yeast adhesion rate when the epithelial cells were pre-treated. This study is currently being developed with the evaluation of mutagenic and genotoxic potentials of several homeopathic solutions.&#x0D; &#x0D; Aims: The goal of this study was to assess the genotoxic and mutagenic potentials of different homeopathic potencies of C. albicans.&#x0D; &#x0D; Methodology: One part of C. albicans yeast obtained from Brazilian patient’s blood [4] was diluted in 9 parts of sterile water. This sample was submitted to 100 mechanical succussions (approximately 3 Hz), using Autic® Brazilian machine, originating the first dilution (1x). Then, 1 ml of this solution was diluted in 9 ml of solvent, submitted to 100 succussions, obtaining 2x potency. This procedure was successively repeated to obtain 30x potency, according to Brazilian Homeopathic Pharmacopoeia [5]. By the same technique, water vehicle was prepared until 30x to be used as control. All samples were prepared in sterile and aseptic conditions, using laminar flow cabinet, class II and were stored in the refrigerator (8ºC). The samples 1x, 6x, 12x, 18x, 24x and 30x of C. albicans and water 30x (vehicle control) were analysed by: the Inductest, which assesses the ability of physical or chemical agents to promote lysogenic induction as a reflection of damage in DNA molecules in lysogenic bacteria, and the Ames test, which uses indicator strains of Salmonella typhimurium, sensitive to substances that can induce different types of mutation.&#x0D; &#x0D; Results: In the Inductest no decrease in survival fraction of bacteria and no increase in the formation of lysogenic induction were detected independently of the homeopathic potency employed. The same profile was obtained after the Ames test, with similar results to negative control.&#x0D; &#x0D; Conclusion: Afterwards, we can conclude that these samples are not able to induce DNA damage in the cells tested. So, the use of this medicine does not present any side effects related to mutagenesis and genotoxicity.

Correlating single-molecule rupture mechanics with cell population adhesion by yeast display

Here, we present a method based on yeast surface display that allows for direct comparison between population-level cell adhesion strength and single-molecule receptor-ligand rupture mechanics. We developed a high-throughput yeast adhesion assay in which yeasts displaying monomeric streptavidin (mSA) or enhanced mutant mSA were adhered to a biotinylated coverglass submerged in fluid. After exposure to shear stress (20–1000 dyn/cm2) by rapid spinning of the coverglass, cells were imaged to quantify the midpoint detachment shear stress for the cell population. We then performed atomic force microscope single-molecule force spectroscopy (SMFS) on purified mSA variants and identified correlations between single-molecule rupture force distributions and cell population adhesion strength. Several features of yeast display were important for successful correlations of adhesion strength to be drawn, including covalent attachment of the receptor to the cell wall, a precisely defined molecular pulling geometry, repression of nonspecific adhesion, and control for multivalency. With these factors properly taken into account, we show that spinning disk cell adhesion assays can be correlated with SMFS and are capable of screening the mechanical strength of receptor-ligand complexes. These workflow enhancements will accelerate research on mechanostable receptor-ligand complexes and receptor-mediated cell adhesion.

Polydopamine-Assisted Surface Modification of Ti-6Al-4V Alloy with Anti-Biofilm Activity for Dental Implantology Applications

Coating the surfaces of implantable materials with various active principles to ensure inhibition of microbial adhesion, is a solution to reduce infections associated with dental implant. The aim of the study was to optimize the polydopamine films coating on the Ti-6Al-6V alloy surface in order to obtain a maximum of antimicrobial/antibiofilm efficacy and reduced cytotoxicity. Surface characterization was performed by evaluating the morphology (SEM, AFM) and structures (Solid-state 13C NMR and EPR). Antimicrobial activity was assessed by logarithmic reduction of CFU/mL, and the antibiofilm activity by reducing the adhesion of Escherichia coli, Staphylococcus aureus, and Candida albicans strains. The release of NO was observed especially for C. albicans strain, which confirms the results obtained for microbial adhesion. Among the PDA coatings, for 0.45:0.88 (KMnO4:dopamine) molar ratio the optimal compromise was obtained in terms of antimicrobial activity and cytotoxicity, while the 0.1:1.5 ratio (KMnO4:dopamine) led to higher NO release and implicitly the reduction of the adhesion capacities only for C. albicans, being slightly cytotoxic but with moderate release of LDH. The proposed materials can be used to reduce the adhesion of yeast to the implantable material and thus inhibit the formation of microbial biofilms.

Candida albicans Biofilm Inhibition by Two Vaccinium macrocarpon (Cranberry) Urinary Metabolites: 5-(3',4'-DihydroxyPhenyl)-γ-Valerolactone and 4-Hydroxybenzoic Acid.

Candida spp. are pathobionts, as they can switch from commensals to pathogens, responsible for a variety of pathological processes. Adhesion to surfaces, morphological switch and biofilm-forming ability are the recognized virulence factors promoting yeast virulence. Sessile lifestyle also favors fungal persistence and antifungal tolerance. In this study, we investigated, in vitro, the efficacy of two urinary cranberry metabolites, 5-(3′,4′-dihydroxy phenyl)-γ-valerolactone (VAL) and 4-hydroxybenzoic acid (4-HBA), in inhibiting C. albicans adhesion and biofilm formation. Both the reference strain SC5314 and clinical isolates were used. We evaluated biomass reduction, by confocal microscopy and crystal violet assay, and the possible mechanisms mediating their inhibitory effects. Both VAL and 4-HBA were able to interfere with the yeast adhesion, by modulating the expression of key genes, HWP1 and ALS3. A significant dose-dependent reduction in biofilm biomass and metabolic activity was also recorded. Our data showed that the two cranberry metabolites VAL and 4-HBA could pave the way for drug development, for targeting the very early phases of biofilm formation and for preventing genitourinary Candida infections.

Multivalent Presentations of Glycomimetic Inhibitor of the Adhesion of Fungal Pathogen Candida albicans to Human Buccal Epithelial Cells.

Candida albicans causes some of the most prevalent hospital-acquired fungal infections, particularly threatening for immunocompromised patients. C. albicans strongly adheres to the surface of epithelial cells so that subsequent colonization and biofilm formation can take place. Divalent galactoside glycomimetic 1 was found to be a potent inhibitor of the adhesion of C. albicans to buccal epithelial cells. In this work, we explore the effect of multivalent presentations of glycomimetic 1 on its ability to inhibit yeast adhesion and biofilm formation. Tetra-, hexa-, and hexadecavalent displays of compound 1 were built on RAFT cyclopeptide- and polylysine-based scaffolds with a highly efficient and modular synthesis. Biological evaluation revealed that the scaffold choice significantly influences the activity of the lower valency conjugates, with compound 16, constructed on a tetravalent polylysine scaffold, found to inhibit the adhesion of C. albicans to human buccal epithelial cells more effectively than the glycomimetic 1; however, the latter performed better in the biofilm reduction assays. Interestingly, the higher valency glycoconjugates did not outperform the anti-adhesion activity of the original compound 1, and no significant effect of the core scaffold could be appreciated. SEM images of C. albicans cells treated with compounds 1, 14, and 16 revealed significant differences in the aggregation patterns of the yeast cells.

Influence of Removable Denture Cleaning Agents on Adhesion of Oral Pathogenic Microflora In Vitro: A Randomized Controlled Trial

Introduction: Removable dentures are used by 20% of the population. These may be accompanied by denture stomatitis in 15-70% of patients. The choice of the optimal cleansing agent for removable dental prostheses is of high significance. Aim: The aim of our research was to study the influence of removable denture cleansing products on the adhesion of microorganisms and yeast. Materials and Methods: We manufactured 144 specimens of standardized round shape with a diameter of 10 mm from 4 types of modern polymeric materials used by prosthetic dentistry to produce removable dentures, 12 specimens of each material were placed into suspensions of bacterial cultures of Staphylococcus aureus, Escherichia coli, Candida albicans, then into “ClearaSept” (Test group 1), “Рrotefix active cleanser” (Test group 2), saline solution (Control group), followed by nutrient media. The adhesion index was calculated and analyzed. Results: There was no reliable lowering of adhesion index of Staphylococcus Aureus to all materials detected in Test group 1 (U=6, p&gt;0.05 for Bio XS; U=8, p&gt;0.05 for Dental D, Denotokeep Peek, Vertex Rapid Simplified). In Test group 2, the adhesion index of Staphylococcus Aureus reliably decreased to all materials compared to the Control group (U=0, p≤0.01). The adhesion index of Candida albicans and Escherichia coli to all materials in Test group 1 had a minor to moderate reliable reduction compared to the Control group (U=0, p≤0.01). Test group 2 showed a significant reliable decrease in Candida albicans and Escherichia coli adhesion index to all materials in comparison with the Control group (U=0, p≤0.01). Conclusion: The research showed an unreliable or minor and moderate reliable decrease in microorganisms adhesion index depending on the microorganism species after treatment of denture material specimens by antibacterial soap “ClearaSept” and a reliable significant decrease in microbial and yeast adhesion after application of Protefix active cleaner solution, which demonstrates a more significant antimicrobial effect in comparison to “ClearaSept” against Staphylococcus aureus, Escherichia coli, and Candida albicans.

The genotypes and virulence attributes of C. albicans isolates from oral leukoplakia.

Background There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation, associated with a minority of such lesions. As no detailed population analysis of yeast isolates from OL is available, we evaluated the virulence attributes, and genotypes of 35 C. albicans from OL, and compared their genotypes with 18 oral isolates from healthy individuals.Material and Methods The virulence traits evaluated were esterase, phospholipase, proteinase, haemolysin and coagulase production, and phenotypic switching activity, and yeast adherence and biofilm formation. DNA from OL and control yeasts were evaluated for A, B or C genotype status.Results Phospholipase, proteinase, and coagulase activity and biofilm formation was observed in 80%, 66%, 97 % and 77 % of the isolates, respectively. Phenotypic switching was detected in 8.6%, while heamolytic, and esterase activity and adherence were noted in all isolates.Conclusions The genotype A was predominant amongst both the OL and control groups. Due to the small sample size of our study a larger investigation to define the role of candidal virulent attributes in the pathogenicity of OL is warranted, and the current data should serve as a basis until then. Key words:C. albicans, oral cavity, leukoplakia, virulence factors, genotyping.

Effect of Some Disinfectant Solutions on the Adherence of Candida albicans to Three Types of Acrylic Resin Denture Base Materials

Objective: Microbial adhesion to denture surface is problematic for denture wearers, especially those with impaired dexterities. This study aimed to evaluate the effectiveness of two plant extracts (clove and Basil) in addition to Chlorhexidine on candida Albicans adherence to (heat, cold, light) activated acrylic denture base materials. &#x0D; Methods: Two herbal extracted clove (Eugenia caryohyllata) and Basil (Ocimum basilicum) were prepared by drying, ground to powder, and extracted with ethanol chlorhexidine gluconate of 0.12% were used as three disinfectant solutions. One hundred and five square acrylic samples were prepared from (heat, cold, and light) activated acrylic resin denture base materials in dimensions of 10×10×2 mm for the study. The disk diffusion test was used to determine the susceptibility of C. Albicans to disinfectant solutions. The adhesion of yeast to the acrylic resin samples was measured with a light microscope by measuring the number of fungal cells in the corners of the square and expressed as no. of cells/mm2. Statistical analysis was done by ANOVA to compare the mean of readings between disinfectant solutions and post-hoc t-test in which the p-value is less than 0.05.&#x0D; Results: Statistically significant differences (p&lt;0.05) of adhesion of C.albicans were found on the surfaces of three types of activated acrylic resin materials with means of 19.18, 46.25, and 26.50 cell/mm2on heat, light, and cold cure respectively and after immersing the specimens on the disinfectant solutions regarding the highest effect of the disinfectant solutions was seen in chlorhexidine gluconate of 0.12% which demonstrate 3.11, 5.89 and 5.43 cell/mm2 followed by Basil with means of 6.75, 13.57 and 10.11 cell/mm2 on heat, light and cold cure acrylic resin specimens correspondingly, then the clove and finally distilled water. &#x0D; Conclusions: Both clove buds and basil leaves extracted solutions exhibited high antifungal activity besides Chlorhexidine on the surface of denture base materials. The highest inhibition zone was seen in Chlorhexidine, followed by Basil, clove, and distilled water, respectively. The number of fungal cell adhesion to the three types of denture base was decreased in the three disinfectant solutions when compared to distilled water (control group).

Effects of in vitro treatment with amphotericin B, fluconazole, caspofungin and voriconazole on the ultrastructure of diutina (Candida) rugosa biofilms

Background: Candida species are considered to be part of the normal microbiota in the gastrointestinal and genitourinary tracts of human, however they have the propensity to invade and cause disease in immunocompromised individual. Medical devices such as intravenous catheters and surgical interventions provide pathogenic Candida with a surface to adhere to form biofilm. Candida rugosa has been cited as an emerging fungal pathogen. Lately, Candida rugosa was reclassified as Diutina rugosa. This study investigates the biofilm architecture and ultrastructure of Diutina (Candida) rugosa (D. rugosa) before and after antifungal treatment, quantifies its total carbohydrate and total protein levels, and identifies the Sessile Minimum Inhibition Concentrations (SMICs) of amphotericin B, caspofungin, fluconazole, and voriconazole. Methods and materials: Confocal scanning laser microscopy (CSLM) and scanning electron microscopy (SEM) were used to visualize D. rugosa biofilms at different developmental phases and to assess the effect of the antifungal agents on the ultrastructure of the biofilms. The growth kinetics of Diutina biofilms were quantified using XTT reduction and crystal violet assays. Total carbohydrate and total protein levels were quantified using phenol-sulfuric acid method and Bradford's method, respectively. The antifungal susceptibility test was performed using serial doubling dilution method. Results: From the SEM micrographs, D. rugosa biofilms are composed of adherent yeast cells and blastospores with hyphal elements. The ultrastructure of the yeast cells were collapsed and disfigured upon exposure to amphotericin B, fluconazole and voriconazole and the biofilms presented with punctured yeast morphology upon exposure to caspofungin at their respective SMICs. The matrix thickness of embedded yeast cells from CLSM micrographs was 3.9μm at 48h. However, there was reduction in the thickness of the biofilms upon antifungal exposure. The antifungal exposed biofilms exhibit bright, diffuse, green-yellow fluorescence that were not seen in the control. D. rugosa biofilm matrices revealed 172.57μg/mL of carbohydrate and 27.11μg/mL of protein content. The SMICs of Diutina biofilm for amphotericin B is 1024μg/mL, caspofungin is 512 μg/mL, whereas fluconazole and voriconazole is 2048μg/mL respectively. Conclusion: The findings of the effect of antifungal agents on the D. rugosa biofilm ultrastructure will aid in understanding the mechanisms that contribute to resistance towards these antifungal agents.

Changes in Adhesion of Candida tropicalis Clinical Isolates Exhibiting Switch Phenotypes to Polystyrene and HeLa Cells.

Candida tropicalis is an important human pathogen that can undergo multiple forms of phenotypic switching. We aimed to evaluate the effect of phenotypic switching on the adhesion ability of C. tropicalis. C. tropicalis morphotypes included parental phenotypes (clinical isolates) and switch phenotypes (crepe, revertant of crepe-CR, rough, revertant of rough-RR, irregular center and revertant of irregular center-ICR). Adhesion to polystyrene and HeLa cells was determined by crystal violet assay. The percentage of HeLa cells with adhered yeasts and the number of adhered yeasts per HeLa cell were determined by light microscopy. Filamentation among adhered cells was assessed by direct counting. On polystyrene, 60% of the switch strains showed difference (p < 0.05) on adhesion ability compared to their parental counterpart strains, and altered thickness of adhered cells layers. Filamentation was increased among adhered cells of the switched strains compared to parental strains. A positive correlation was observed between adhesion on polystyrene and filamentation for morphotypes of the system 49.07. The majority of the switched strains showed higher adhesion capability to HeLa cells in comparison to the adherence of the clinical strains. All revertant strains showed a higher number of yeast cells per HeLa cell compared to their variant counterparts (p < 0.05), with exception of the ICR. Our findings indicate that switching events in C. tropicalis affect adhesion and filamentation of adhered cells on polystyrene and HeLa cells. The rise of switch strains with increased adhesion ability may contribute to the success of infection associated with C. tropicalis.

Effect of rotary swaging and subsequent aging on the implant-relevant properties of magnesium alloy WE43

The magnesium alloy WE43 were pre-strained by rotary swaging (RS) with a final temperature of 350°C. RS led to a significant grain refinement with the formation of a predominantly subgrain structure. The average size of the structural elements decreased up to 450±50 nm after RS. In addition, the RS-induced precipitation of intermetallic Mg41Nd5 particles with an average size of 210±13 nm was observed. Subsequent heat treatment caused the average size of structural elements and intermetallic particles to grow to 781±88 nm and 494±51 nm, respectively. After RS, the ultimate tensile strength (UTS) of the alloy rose to 363±2 MPa with tensile elongation of 11.4±0.6%. After heat treatment, the UTS of the alloy increased to 376±9 MPa, with some drop of tensile elongation to 7.6±0.4%. Interestingly, the biocorrosion resistance of the alloy was not compromised by RS, while subsequent heat treatment of the swaged alloy reduced its biodegradation rate. No significant differences in the biocompatibility of the alloy WE43 between different microstructural states were observed. It was found that RS with subsequent aging of the alloy WE43 reduces the adhesion of yeast to its surface, which in the long term may reduce the risk of infectious complications after orthopedic surgery.

Automated quantification of Candida albicans biofilm-related phenotypes reveals additive contributions to biofilm production

Biofilms are organized communities of microbial cells that promote persistence among bacterial and fungal species. Biofilm formation by host-associated Candida species of fungi occurs on both tissue surfaces and implanted devices, contributing to host colonization and disease. In C. albicans, biofilms are built sequentially by adherence of yeast to a surface, invasion into the substrate, the formation of aerial hyphal projections, and the secretion of extracellular matrix. Measurement of these biofilm-related phenotypes remains highly qualitative and often subjective. Here, we designed an informatics pipeline for quantifying filamentation, adhesion, and invasion of Candida species on solid agar media and utilized this approach to determine the importance of these component phenotypes to C. albicans biofilm production. Characterization of 23 C. albicans clinical isolates across three media and two temperatures revealed a wide range of phenotypic responses among isolates in any single condition. Media profoundly altered all biofilm-related phenotypes among these isolates, whereas temperature minimally impacted these traits. Importantly, the extent of biofilm formation correlated significantly with the additive score for its component phenotypes under some conditions, experimentally linking the strength of each component to biofilm mass. In addition, the response of the genome reference strain, SC5314, across these conditions was an extreme outlier compared to all other strains, suggesting it may not be representative of the species. Taken together, development of a high-throughput, unbiased approach to quantifying Candida biofilm-related phenotypes linked variability in these phenotypes to biofilm production and can facilitate genetic dissection of these critical processes to pathogenesis in the host.