Basic characteristics of the process of Candida adhesion to human epitheliocytes

The adhesion of fungi belonging to the genus Candida to the epithelial cells of the mouth cavity reached its maximum at pH 6.2-7.0. The process of adhesion had similar dynamics at temperatures of 37 degrees, 28 degrees and 25 degrees C, but the adhesive activity decreased 2 times when temperature dropped from 37 degrees to 25 degrees and 4 times when temperature dropped to 4 degrees C. The introduction of the ions Ca2+ (1 and 10 mM) and Mg2+ (10 mM) led to the increase of adhesion by 80, 100 and 24% respectively. The heating of the fungal cells at 100 degrees C (for 1 hour) and at 63 degrees C (for 2 hours) decreased adhesion to 8 and 24% respectively, and treatment with formaldehyde (for 24 hours) decreased adhesion to 70% of that observed in experiments with live Candida cells.     

Effect of dietary carbohydrates on the in vitro epithelial adhesion of Candida albicans, Candida tropicalis, and Candida krusei

Adhesion to epithelial surfaces is considered as a critical step in the pathogenesis of oral candidosis. Therefore, the effects of the most commonly consumed dietary carbohydrates on the adhesion of Candida albicans, Candida tropicalis, and Candida krusei to monolayered HeLa cells were investigated. Adherence of C. albicans and C. tropicalis appeared significantly promoted by incubation in defined medium containing a high concentration (500 mM) of fructose, glucose, maltose, and sucrose (p < 0.001). C. albicans organisms grown in sucrose elicited maximal increase in adhesion, whereas adhesion of C. tropicalis and C. krusei was enhanced to the greatest extent when cultured in glucose. Maltose and fructose also promoted adherence of C. albicans and C. tropicalis (p < 0.001), but to a lesser extent than sucrose and glucose. On the other hand, sorbitol-grown yeasts demonstrated a marginal increase in adhesion (p > 0.01). Xylitol only significantly reduced adherence of C. albicans (p < 0.001). These results suggest that the frequent consumption of carbohydrates, such as sucrose, glucose, maltose, or fructose, might represent a risk factor for oral candidosis. The limitation of their consumption by substituting xylitol or sorbitol could be of value in the control of oral Candida colonization and infection.     

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4-3.3 μg ml(-1)). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ～90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.     

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4–3.3 μg ml^?1). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ～90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.     

The study of adhesion of Candida albicans to the selected acrylic resins

The study has been performed on 3 acrylic resins used to fabricate removable dentures. Aim of the study was to detect possible differences in Candida albicans' adhesion within particular materials. Polished and non-polished samples were made, than these samples were sunk in precipitates containing Candida albicans material. Adhesion of Candida albicans to the surface of the materials occured within a concentration of 10. After 24 hours of incubation differences were found concerning the number of the plate cultures. Most of all plate cultures were observed on Lucitone 199, fewer on Zhermacryl, the poorest one was found on Palaxpress resin. Considerable number of plate cultures occured on non-polished samples relating to polished ones. After 48 hours of incubation further development of Candida albicans took place, with differences concerning various materials.     

地塞米松影响念珠菌对抗真菌药物敏感性的实验研究

目的 探讨地塞米松在体外试验中是否影响念珠菌对抗真菌药物的敏感性,以了解糖皮质激素与抗真菌药物直接作用于念珠菌时是否存在相互作用。方法 用微量液体培养基稀释法分别测定26株白念珠菌与地塞米松（0．2mg／ml）共同孵育前、孵育24～48h及7d时氟康唑、伊曲康唑、两性霉素B的最低抑菌浓度（MIC）值,并作对照。结果 白念珠菌与地塞米松孵育24～48h后、孵育后第7d氟康唑和伊曲康唑的MIC值升高,分别与孵育前的MIC值存在统计学差异,但孵育24～48h后的MIC与孵育后第7d的MIC无统计学差异;白念珠菌与地塞米松共同孵育24～48h后两性霉素B的MIC值也较孵育前升高,但第7d的MIC值与孵育前无差异。结论 地塞米松可增加三种抗真菌药物对于白念珠菌的MIC,但三种抗真菌药物间存在差异,表明地塞米松对于氟康唑和伊曲康唑体外抗白念珠菌的活性有拮抗作用,但没有时间依赖性,地塞米松对于两性霉素B的影响较氟康唑和伊曲康唑小,且影响时间较短。     

Correlation between cell-surface hydrophobicity of Candida albicans and adhesion to buccal epithelial cells

Adhesion of four isolates of Candida albicans to buccal epithelial cells was determined after growth of the yeasts in defined medium containing 50 mM glucose or 500 mM galactose as the carbon source. With each isolate, adhesion of galactose-grown yeasts was significantly higher than that of glucose-grown organisms. Yeast cell-surface hydrophobicity was assessed by two methods, a modified hydrocarbon adhesion assay and a more sensitive polystyrene microsphere assay. All four isolates were significantly more hydrophobic after growth on 500 mM galactose than after growth on 50 mM glucose. Overall, a strong positive correlation between adhesion and surface hydrophobicity was observed (r = 0.965). These results are discussed in relation to the role of yeast-surface hydrophobicity in pathogenesis.     

In vitro evaluation of adherence of Candida albicans,Candida glabrata,and Streptococcus mutans to an acrylic resin modified by experimental coatings

This study evaluated the effect of experimental coatings, containing zwitterion or hydrophilic monomers, on the adherence of Candida albicans, Candida glabrata, and Streptococcus mutans to an acrylic resin. Acrylic samples (smooth or rough surfaces) were left untreated (control) or coated with one of the following experimental coatings: 3-hydroxypropylmethacrylate (HP) or sulfobetaine methacrylate (S), at concentrations of 25, 30, or 35%. Half of the specimens were coated with saliva. The adhesion test was performed by incubating specimens in C. albicans, C. glabrata, and S. mutans suspensions at 37°C for 90?min. The number of adhered microorganisms was determined by metabolic activity (XTT) and by cell viability (CFU). All coated specimens exhibited lower absorbance and CFU values compared to control specimens. Saliva and roughness did not promote microorganism adherence. An XPS analysis confirmed the modification in the chemical composition of the coatings in the experimental samples. These experimental coatings significantly reduced the adherence of C. albicans, C. glabrata and S. mutans to acrylic resin.     

大蒜素对白色念珠菌生长的抑制作用

探讨大蒜素对白色念珠菌生长的抑制作用。以NCCLS方案检测了胡桃楸提取物和伊曲康唑(ICZ)、氟康唑(FCZ)、两性霉素B(AMB)和5-氟胞嘧啶(5-FC)对133株白念珠菌体外生长抑制作用。标准菌株JC1A的M IC结果表明大蒜素提取物对白念珠菌的抗菌作用相当于FCZ,略低于ICZ、AMB和5-FC;临床分离株对ICZ和FCZ的耐药率很高,对大蒜素提取物的耐药率较低。大蒜素提取物对白色念珠菌生长有强力抑制作用。     

A rapid screening test to distinguish between Candida albicans and Candida dubliniensis using NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy combined with a statistical classification strategy (SCS) successfully distinguished between Candida albicans and Candida dubliniensis. 96% of the isolates from an independent test set were identified correctly. This proves that this rapid approach is a valuable method for the identification and chemotaxonomic characterisation of closely related taxa. Most discriminatory regions were correlated with metabolite profiles, indicating biochemical differences between the two species.     

Effect of various components of the fungal cell wall on adhesion of Candida albicans to the mouth mucosa epithelium in vitro]

An influence of mannan++, its component methyl-D-mannopyranoside+ and N-acetylglucosamine on in vitro adhesion of Candida albicans strains to buccal mucosal epithelium was studied. These substances inhibited adhesion when added to adherence test in a concentration of 10 mg/ml and 25 mg/ml despite whether were added to the test incubation medium or when preincubated with fungi or epithelial cells. Preincubation of fungal cells and epithelial cells with mannan had no influence on attachment; preincubation of epithelial cells with methyl-D-mannopyranoside+ and N-acetylglucosamine decreased adherence significantly. On the other hand preincubation of fungal calls with methyl-D-mannopyranoside+ increased their adhesive properties, having no influence on adherence after preincubation of fungi with N-acetylglucosamine.     

Experimental study of the effect of corticosteroid preparations on the adhesion of Candida genus fungi to the epitheliocytes of mucous membranes

The effect of corticosteroids on the adherence of Candida cells to epithelial cells was studied with the use of the original modification of the in vitro adherence assay. The administration of hydrocortisone acetate to mice resulted in the increased adherence of the pathogenic fungi to epithelial cells: after 10-day hormone treatment the adherence number and the adherence index increased, respectively, to 230% and 360% of control values. After 20-day treatment these characteristics increased, respectively, to 260% and 700%. The adherence of C. albicans to vaginal epithelial cells in female mice receiving corticosteroids increased in comparison with that in the control animals at estrus: the adherence number increased to 220% and the adherence index, to 470% of the level observed in the controls.     

Prevalence of Candida albicans and Trichomonas vaginalis in pregnant women in Havana City by an immunologic latex agglutination test

We aimed to estimate the prevalence of Candida albicans and Trichomonas vaginalis in immunocompetent pregnant women living in Havana City, Cuba, with or without symptoms of vaginitis, using a sample of 640 women from 6 Gyneco-obstetrics hospitals, which represents 2.5% of total yearly pregnant women. Diagnosis was made using a new latex agglutination kit (Newvagin C-Kure, La Habana, Cuba). Clinical sensitivity and specificity of this assay were validated against culture method, with 467 and 489 clinical specimens for Candida albicans and Trichomonas vaginalis, respectively. Results showed that the kit clinical sensitivity was 100% for Candida albicans and 86.7% for Trichomonas vaginalis compared with a clinical specificity of 93.3% for Candida albicans and 95.1% for Trichomonas vaginalis by culture. The prevalence of candidiasis was determined to be 42.3% (95% confidence interval [CI] 3.8%); the prevalence of trichomoniasis was 9.84% (95% CI 2.3%). In our sample, 48.7% of the women tested negative with respect to both candidiasis and trichomoniasis. Only 6.41% of the cases yielded inconclusive results. The test has high sensitivity, and our results indicate a relatively high prevalence of both infections. However, a significant difference (P < .001) was also observed in candidiasis and trichomoniasis prevalence among hospitals corresponding to the quantity of women with clinical vaginitis. No difference was observed between diabetics and nondiabetics, probably due to the special care of diabetic pregnant women. We conclude that the method is useful for this kind of vaginitis prevalence study and that candidiasis and trichomoniasis prevalences in pregnant women of Havana are 38.5% to 46.2 % (95% CI) and 7.5% to 12.1% (95% CI), respectively.     

In vivo and in vitro anaerobic mating in Candida albicans

Candida albicans cells of opposite mating types are thought to conjugate during infection in mammalian hosts, but paradoxically, the mating-competent opaque state is not stable at mammalian body temperatures. We found that anaerobic conditions stabilize the opaque state at 37 degrees C, block production of farnesol, and permit in vitro mating at 37 degrees C at efficiencies of up to 84%. Aerobically, farnesol prevents mating because it kills the opaque cells necessary for mating, and as a corollary, farnesol production is turned off in opaque cells. These in vitro observations suggest that naturally anaerobic sites, such as the efficiently colonized gastrointestinal (GI) tract, could serve as niches for C. albicans mating. In a direct test of mating in the mouse GI tract, prototrophic cells were obtained from auxotrophic parent cells, confirming that mating will occur in this organ. These cells were true mating products because they were tetraploid, mononuclear, and prototrophic, and they contained the heterologous hisG marker from one of the parental strains.     

Evolutionary dynamics of Candida albicans during in vitro evolution

While mechanisms of resistance to major antifungal agents have been characterized in Candida albicans, little is known about the evolutionary trajectories during the emergence of drug resistance. Here, we examined the evolutionary dynamics of C. albicans that evolved in vitro in the presence or absence of fluconazole using the visualizing evolution in real-time (VERT) method, a novel experimental approach that facilitates the systematic isolation of adaptive mutants that arise in the population. We found an increase in the frequency of adaptive events in the presence of fluconazole compared to the no-drug controls. Analysis of the evolutionary dynamics revealed that mutations that led to increased drug resistance appeared frequently and that mutants with increased levels of resistance arose in independent lineages. Interestingly, most adaptive mutants with increased fitness in the presence of the drug did not exhibit a significant fitness decrease in the absence of the drug, supporting the idea that rapid resistance can arise from mutations in strains maintained in the population prior to exposure to the drug.     

Candida albicans antigens studied in complement fixation test and agar gel diffusion test

Summary The antigens prepared simultaneously from seven type ACandida albicans strains by cell disintegration by means of sonic vibrations, grinding with the sea-sand, autolysis and the antigens precipitated with acetone from fluid cultures were studied in complement fixation test and agar gel diffusion test against selected rabbit immune sera. The complement fixation test was performed in plexiglass plates as chessboard titration. The agar gel diffusion test was performed in petri dishes according toOuchterlony and according toBjörklund's specific inhibition of precipitation. The activity of studied antigens determined in complement fixation test was high. The antigen titers were ranging from 1/512 to 1/8192. The reaction observed in agar gel diffusion test were also strong and precipitation spectra consisted of 1–3 lines. The reaction pattern obtained in both tests depended on the character of the analysed reagents. TheBjörklund's modification was successfully applied to serological grouping of the strains under study. Sixteen human sera collected from patients with symptoms of Asthma bronchiale and Bronchitis chronica, from whose sputumCandida albicans was isolated, were tested in both tests. The researches made on human sera were intended as preliminary tests.Head of the department: Prof. Dr.Z. Przybylkiewicz.