Yeast Adhesion Research Articles

Quantitative cell wall protein profiling of invasive and non-invasive Saccharomyces cerevisiae strains

A new, simple approach for the isolation and quantitative analysis of the cell wall (CW) proteins from invasively growing Saccharomyces cerevisiae strains is described in this contribution. The proposed method was proved compatible with agar-invasion assays and was demonstrated to be useful as a screening tool for rapid analysis of CW protein determinants related to yeast adhesion and invasion processes. CW protein isolation was performed enzymatically on viable cells by using mild, isosmotic reaction conditions and pure, proteinase free glucanase, thus avoiding destruction of cells and protein structures, which is a drawback of the existing methods based on hot SDS, DTT or NaOH treatment. Moreover, the method requires as low as 10 mg of collected cell biomass for sufficient protein yield, which makes it suitable for the study of yeast invasion at the proteomic level. The extraction protocol was optimized for fast, direct analysis of multiple protein samples by SDS-PAGE, avoiding pre-concentration or purification steps, but still preserving high resolution of protein bands. The developed method was used to compare CW protein profile of i) invasive and non-invasive strains, ii) invasive and non-invasive morphological part of the colony and iii) cells cultivated at optimal and increased growth temperature. Results of quantitative SDS-PAGE analysis of S. cerevisiae CW proteins revealed the presence of up to 20 protein bands with molecular masses in the range 60–220 kDa. In addition, comparative analysis of CW protein profiles resulted in significant changes in the protein profile expression relevant to different cultivation temperature, cell morphology (invasive vs. non-invasive growth) and yeast strain.

Effect of substrate surface hydrophobicity on the adherence of yeast and hyphalCandida

A biofilm composed of various microorganisms including Candida is found on denture surfaces and is likely to be involved in the etiology of denture-induced stomatitis. The purpose of this study was to examine the role of hydrophobic interactions in candidal adherence to acrylic surfaces, particularly that of the hyphal form of Candida albicans. Candida clinical isolates were used. Acrylic plates coated with carrageenan and hydrocolloid (Hitachi chemical, Tokyo, Japan) were used as a hydrophilic substratum. A microbial suspension was placed on each acrylic plate and incubated. All plates were washed in phosphate-buffered saline containing CaCl(2) and MgCl(2) [PBS (+)] and cells still adhering to the acrylic surface were collected by 0.25% trypsin treatment. Cell-surface hydrophobicity was estimated using a modification of the technique used to measure adherence to hydrocarbons. When the acrylic plates were coated with hydrophilic materials, the adherence of hydrophobic clinical isolates of Candida and the hydrophobic hyphal C. albicans decreased, whereas the adherence of non-hydrophobic Candida was not affected or increased. We suggest that hydrophilic coating of denture surfaces could be a potent method for reduction of the adherence of relatively hydrophobic fungal cells, particularly hyphal C. albicans, which causes denture stomatitis and related infections.

In vitro studies of anticandidal activity of goniothalamin enantiomers

The antifungal activity of (R)-goniothalamin (1) and (S)-goniothalamin (ent-1) was evaluated against six Candida species. The in vitro effect of these compounds on yeast adhesion to human buccal epithelial cells (BEC) and Candida albicans and C. dubliniensis biofilms progression were also investigated. Yeast susceptibility was evaluated by broth microdilution assay and showed that ent-1 exhibited higher potency against all fungal clinical isolated when compared to compound 1. Compounds 1 and ent-1 were as potent as fluconazole in inhibiting the adhesion of C. albicans and C. dubliniensis to BEC. XTT-reducing assay and scanning electron microscopy revealed that 1 and ent-1 were twice as potent as fluconazole in the inhibition of yeast biofilms progression. Our findings indicate that compounds 1 and ent-1 are potent anticandidal agents. This study highlights goniothalamin enantiomers as promising lead compounds for the design of new antifungal with inhibitory activity on yeast adhesion and biofilm progression.

High environmental iron concentrations stimulate adhesion and invasive growth ofSchizosaccharomyces pombe

We have found that a high iron concentration in solid complete cultivation medium potentiates cell-cell and cell-surface adhesion of the fission yeast Schizosaccharomyces pombe. Spotted giant colonies grown on iron-rich media were found to be more compact and more resistant to washing than those grown on plates with a standard iron content. Furthermore, we have documented that excess environmental iron stimulates the invasive growth of S. pombe (and Saccharomyces cerevisiae). Three-dimensional, branched, washing-resistant structures composed mostly of elongated, but separate fission yeast cells, were formed within the solid agar medium. The degree of both adhesion and invasion displayed a specific, iron concentration-dependent response. Our results suggest a novel link between iron availability and the intensively studied and important fungal virulence factors, adhesion and invasion.

The initial single yeast cell adhesion on glass via optical trapping and Derjaguin–Landau–Verwey–Overbeek predictions

We used an optical tweezer to investigate the adhesion of yeast Saccharomyces cerevisiae onto a glass substrate at the initial contact. Micromanipulation of free-living objects with single-beam gradient optical trap enabled to highlight mechanisms involved in this initial contact. As a function of the ionic strength and with a displacement parallel to the glass surface, the yeast adheres following different successive ways: (i) Slipping and rolling at 1.5 mM NaCl, (ii) slipping, rolling, and sticking at 15 mM NaCl, and (iii) only sticking at 150 mM. These observations were numerous and reproducible. A kinetic evolution of these adhesion phenomena during yeast movement was clearly established. The nature, range, and relative intensity of forces involved in these different adhesion mechanisms have been worked out as a quantitative analysis from Derjaguin-Landau-Verwey-Overbeek (DLVO) and extended DLVO theories. Calculations show that the adhesion mechanisms observed and their affinity with ionic strength were mainly governed by the Lifshitz-van der Waals interaction forces and the electrical double-layer repulsion to which are added specific contact forces linked to "sticky" glycoprotein secretion, considered to be the main forces capable of overcoming the short-range Lewis acid-base repulsions.

Can intrauterine contraceptive devices be a Candida albicans reservoir?

Background The in vitro adherence of Candida albicans isolated from vaginal exudates of patients with vulvovaginal candidiasis (VVC) to intrauterine contraceptive devices (IUDs) and biofilm formation capacity were evaluated. Study Design This research was conducted with two vaginal C. albicans isolates. The adherence on IUD by both radiomarked adhesion assay and scanning electron microscopy, and the biofilm production capacity by spectrophotometric method were determined. Results The yeasts adhered strongly to different parts of the IUD (covered with copper wire, without copper wire and tail), and there was no significant difference in the rates of adhesion to the different parts (p=.7771). The vaginal yeasts showed a high capacity to produce biofilm. Conclusions Two vaginal yeasts evaluated showed a high capacity to produce biofilm on IUD. It was confirmed that all parts of the IUD allow the adherence of yeasts. The adherence of C. albicans to different parts of the IUD and its formation of biofilm seems to be important attributes influencing the occurrence of VVC and recurrent VVC.

Vaginal yeast adherence to the combined contraceptive vaginal ring (CCVR)

Background The purpose of this study was to evaluate the in vitro adherence of different yeasts, isolated from vaginal exudates of patients with vulvovaginal candidiasis (VVC), to the combined contraceptive vaginal ring — NuvaRing®. Study Design Four isolates of Candida sp. and one isolate of Saccharomyces cerevisiae were used. Adherence assays were carried out through colony-forming units per milliliter (CFU/mL), radiolabeled quantification and scanning electron microscopy (SEM) of the ring, and the cell surface hydrophobicity (CSH) of the yeasts was determined. Results All the yeasts were capable of adhering to the vaginal ring, as determined by CFU/mL and in the radiolabeled assay. CSH was compatible with the adherence by CFU/mL. Conclusion SEM proved the adhesion, which was different between Candida albicans and C. tropicalis. The adherence of the tested yeasts to the ring could potentially facilitate the development of VVC and recurrent VVC in susceptible patients using this contraceptive method.

Attachment and entry of Candida famata in monocytes and epithelial cells

Candida albicans is considered the main pathogenic yeast responsible for a multitude of infective disorders. However, other yeasts, such as Candida famata, are being recognized as potential emerging pathogens that cause several types of infections in humans and animals. Consequently, we have investigated the adhesion and internalization of Candida famata into monocytes and epithelial cells. The interaction of the yeast with the cells is very rapid and takes place during the first 15 min of injection. However, the affinity of the yeast for the cells varies, THP-1 (human monocytes) being the highest and followed in decreasing order by HeLa (human carcinoma), HaCaT, and Pam-212 (human and mouse keratinocytes, respectively). Heat inactivation or treatment with nystatin, significantly decreases yeast adhesion to cells. Immunofluorescence, as well as scanning and transmission electron microscopy, reveals that cell lines are able to internalize C. famata. At 48 h after infection, most of the yeasts located inside cells appear degraded, but some yeasts recovered from lysed cells, were still viable. Adhesion and internalization of C. famata into HeLa cells were found to be lower than those of C. albicans and C. glabrata, but higher than those of S. cerevisiae. In addition, infection with C. famata results in actin microfilaments rearrangement. This article presents novel data in the interaction of this pathogenic yeast with mammalian cells.

The involvement of physico‐chemical interactions in the adhesion of Candida albicans and Candida dubliniensis to epithelial cells

Candida albicans and Candida dubliniensis are two pathogenic yeasts particularly hazardous to immunocompromised patients. Adhesion of yeast cells to epithelium is considered one of the virulence factors and its study is of major importance. The main aim of this study was the comparison of the influence of physico-chemical properties on the adhesion of C. albicans and C. dubliniensis to epithelium. Two strains of each Candida species were used in the adhesion assays to HeLa cells. Adhered cells were enumerated by direct microscopic images observation. Yeast cell surface tension parameters and degree of hydrophobicity were determined by contact angle measurement. Pseudohyphae and hyphae formation was analysed by scanning electron microscopy. Yeast cells presented no statistical differences concerning their physico-chemical surface properties. However, the extent of adhesion to epithelium was different among the four strains. As general conclusion, yeast adhesion to epithelium seems to be strain-dependent and not directly correlated with pseudohyphae formation.

The effect of chlorhexidine and gentian violet on the adherence of Candida spp. to urinary catheters

Urinary tract infection associated with catheters is the most common infection in the hospital environment. The adherence of microorganisms to the surface is a determining factor in colonization and infection. Antiseptics such as chlorhexidine and gentian violet have been shown to be effective against yeasts, as well as having low toxicity and being low-cost. The objective of the present study was to evaluate whether prior treatment of siliconized latex urinary catheters with antiseptics reduces the adherence of yeasts. Two reference strains of C. albicans (ATCC 645448 and ATCC 90028) and six strains isolated from catheter, two each of C. albicans, C. tropicalis, and C. parapsilosis, were used. An in vitro study of adherence was carried out with previously treated catheters, in separate experiments of 1 h and 24 h of incubation under continued shaking. The relative hydrophobicity of the cell surface of the yeasts before and after 1 h of exposure to chlorhexidine was determined. The results demonstrated that both treatments were effective in controlling the adherence of yeast to the catheter (P < 0.0001), and that the hydrophobicity of the eight strains significantly increased after contact with chlorhexidine (P < 0.0001). These results suggest that the antimicrobial activity of chlorhexidine and gentian violet reduces the adherence of the microorganisms to the catheter.

An ectophosphatase activity inCandida parapsilosisinfluences the interaction of fungi with epithelial cells

This study describes the biochemical characterization of a phosphatase activity present on the cell surface of Candida parapsilosis, a common cause of candidemia. Intact yeasts hydrolyzed p-nitrophenylphosphate to p-nitrophenol at a rate of 24.30+/-2.63 nmol p-nitrophenol h(-1) 10(-7) cells. The cell wall distribution of the Ca. parapsilosis enzyme was demonstrated by transmission electron microscopy. The duration of incubation of the yeast cells with the substrate and cell density influenced enzyme activity linearly. Values of V(max) and apparent K(m) for p-nitrophenylphosphate hydrolysis were 26.80+/-1.13 nmol p-nitrophenol h(-1) 10(-7) cells and 0.47+/-0.05 mM p-nitrophenylphosphate, respectively. The ectophosphatase activity was strongly inhibited at high pH as well as by classical inhibitors of acid phosphatases, such as sodium orthovanadate, sodium molybdate, sodium fluoride, and inorganic phosphate, the final product of the reaction. Only the inhibition caused by sodium orthovanadate was irreversible. Different phophorylated amino acids were used as substrates for the Ca. parapsilosis ectoenzyme, and the highest rate of phosphate hydrolysis was achieved using phosphotyrosine. A direct relationship between ectophosphatase activity and adhesion to host cells was established. In these assays, irreversible inhibition of enzyme activity resulted in decreased levels of yeast adhesion to epithelial cells.

Evaluating the Adhesion Force Between Saccharomyces Cerevisiae Yeast Cells and Polystyrene From Shear-Flow Induced Detachment Experiments

The present paper focused on the quantification of the adhesion force between Saccharomyces cerevisiae yeast cells and polystyrene, using laboratory and industrial yeast strains, in a suspending medium of high ionic strength (150 mM NaCl). To this end, shear-flow induced detachment experiments, performed in a flow chamber, were combined with a simplified version of a theoretical model, based on the balance of hydrodynamic forces and torque exerted over yeast cells. It was assumed that yeast adhesion to solid surfaces is mediated by surface proteins and a characteristic thickness of the protein meshwork was thus introduced (25.0 ± 2.5 nm). The experimental determination of the wall shear stress required to remove 50% of the cells initially adherent to polystyrene allowed the estimation of the adhesion force. On this basis, adhesion forces of 6 ± 2 nN and 11 ± 8 nN were obtained for laboratory and industrial strains respectively, reflecting the non-specific interactions, such as Lifshitz-van der Waals and Lewis acid/base interactions, between yeast cells and the polymeric surface. The force magnitude was in the experimental range reported in the literature (between 1 and 50 nN), for a wide variety of solid surfaces and bacterial or fungal species. The mechanism for yeast detachment was established (mainly rolling). The flow chamber and the associated theoretical modelling were thus demonstrated to be a relevant approach to quantify physico-chemical interactions between biological and physical surfaces.

Cryoprotection with L‐ and meso‐Trehalose: Stereochemical Implications

Two unnatural stereoisomers of alpha,alpha-trehalose (L- and meso-trehalose) were synthesized and evaluated as cryoprotectants in order to determine the functional consequences of relative or absolute stereochemistry on their physicochemical properties. Adherent yeast cell cultures were frozen in 10% solutions of D-, L-, and meso-trehalose for periods of 7-28 days, then evaluated by a MTT viability assay. D- and L-trehalose were equally effective in maintaining high rates of cell survival, thus demonstrating the absence of chiral discrimination at the carbohydrate-lipid interface, whereas meso-trehalose was inferior in cryoprotection efficacy. Differential scanning calorimetry revealed a difference in the glass transition temperatures (Tg) of D- and meso-trehalose of nearly 75 degrees C. This can be attributed to differences in conformational behavior, as portrayed by torsional energy maps for rotation about the glycosidic bonds of D- and meso-trehalose. We conclude that the biostabilizing properties of alpha,alpha-trehalose depend on relative stereochemical factors, but are independent of absolute stereochemical configuration.

Influence of acrylic resin polymerization methods and saliva on the adherence of four Candida species

There is limited information on the role of polymerization methods and saliva on the adherence of pathogenic Candida species, with the exception of the adherence of Candida albicans to acrylic resins and the relation of this to surface roughness and surface free energy, which appear to play a major role in the initial phases of microorganism adhesion. This study evaluated the influence of polymerization methods and human whole saliva on the adherence of Candida species to acrylic resin surfaces. Acrylic resin specimens (n=256) measuring 2.5 x 1.2 x 0.2 cm were heat (Classico) or microwave (OndaCryl) polymerized and evaluated for surface roughness using a profilometer, and for surface free energy by measuring the contact angle of a sessile drop of water. For the adherence assay, specimens of each acrylic resin were divided by lottery into 8 groups, according to whether they were exposed to human saliva or not (control), and to 1 of the 4 following suspensions: C albicans, Candida tropicalis, Candida dubliniensis, or Candida glabrata (1 to 5 x 10(6) cells/mL). Adhered yeasts were counted using an optical microscope at x400 magnification. Data were analyzed by 3-way ANOVA and the Tukey honestly significant difference test (alpha=.05). No statistical difference was found for roughness (P=.156), whereas higher surface free-energy values were found for the heat-polymerized acrylic resin (P=.0013). The overall adherence of Candida species was significantly decreased by human saliva (P<.001). Within the limitations of this study, saliva was capable of reducing the adherence of Candida species, whereas roughness and free energy did not influence the adherence rates. As growth on surfaces is a natural part of the Candida lifestyle, its colonization in denture users may be expected. The presence of human whole saliva, however, decreased the overall yeast adherence to the acrylic resin surface, whereas surface roughness and free energy did not interfere with the adherence of Candida species.

Rolling Adhesion of α L I Domain Mutants Decorrelated from Binding Affinity

Activated lymphocyte function-associated antigen-1 (LFA-1, α Lβ 2 integrin) found on leukocytes facilitates firm adhesion to endothelial cell layers by binding to intercellular adhesion molecule-1 (ICAM-1), which is up-regulated on endothelial cells at sites of inflammation. Recent work has shown that LFA-1 in a pre-activation, low-affinity state may also be involved in the initial tethering and rolling phase of the adhesion cascade. The inserted (I) domain of LFA-1 contains the ligand-binding epitope of the molecule, and a conformational change in this region during activation increases ligand affinity. We have displayed wild-type I domain on the surface of yeast and validated expression using I domain specific antibodies and flow cytometry. Surface display of I domain supports yeast rolling on ICAM-1-coated surfaces under shear flow. Expression of a locked open, high-affinity I domain mutant supports firm adhesion of yeast, while yeast displaying intermediate-affinity I domain mutants exhibit a range of rolling phenotypes. We find that rolling behavior for these mutants fails to correlate with ligand binding affinity. These results indicate that unstressed binding affinity is not the only molecular property that determines adhesive behavior under shear flow.

Variable adhesion and diurnal population patterns of epiphytic yeasts on creeping bentgrass

Irrigation and an in vitro agitation assay were used to determine the percentage of the epiphytic yeast community (Cryptococcus, Pseudozyma, Rhodotorula, and Sporobolomyces) adhering to the phylloplane of creeping bentgrass (Agrostis palustris (Huds.) Pers.). Colony-forming units (cfu) of total epiphytic yeast populations (adherent and nonadherent cells) and of adherent populations (cells not removed by agitation) were determined by leaf washing and dilution plating. In an in vitro assay, 40.0% and 57.1% of the yeast adhered to the leaves, whereas, in initial field trials the percentage of adherent yeasts ranged from 40.0% to 71.9% of the total population. Adherent yeast cfu on leaves in the morning were significantly lower on bentgrass (8.0 x 103 to 3.1 x 104 cfu.cm(-2)) compared with total yeast cfu (1.4 x 104 to 4.7 x 104 cfu.cm(-2)) on the nonirrigated control. No differences in yeast populations were observed between irrigated and nonirrigated plots 2 h after the 0900 treatments. Yeast populations followed a diurnal pattern, with larger cfu recovered from bentgrass leaves in the morning and significantly lower populations recovered in the afternoon. At 1400 the adherent yeast were 83.1%-100% of the total yeast population recovered from the leaves. The relative adhesiveness of the epiphytic yeast community on bentgrass leaves is dynamic with nonadherent cells making up a larger percentage of the population in the mornings than the afternoons.

Effects of Quaternary Ammonium Silane Coatings on Mixed Fungal and Bacterial Biofilms on Tracheoesophageal Shunt Prostheses

Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem.

Shear-flow induced detachment of Saccharomyces cerevisiae from stainless steel: Influence of yeast and solid surface properties

The present study focused on the shear-induced detachment of Saccharomyces cerevisiae in adhesive contact with a 316L stainless steel surface using a shear stress flow chamber, with a view to determining the respective influence of the yeast surface properties and the support characteristics. The effect of cultivation of S. cerevisiae yeast cells on their subsequent detachment from the solid surface was particularly investigated. In order to elucidate the role of stainless steel, non-metallic supports were used as control, covering a broad range of surface properties such as surface free energy and roughness: polypropylene (hydrophobic), polystyrene (mildly hydrophobic, similar to stainless steel) and glass (hydrophilic). All materials were very smooth with respect to the size of yeast. First, experiments were carried out on two types of yeast cells, just rehydrated in saline solution, a biological model widely used in the literature. The influence of the ionic strength (1.5 and 150 mM NaCl) on glass and stainless steel was evaluated. Unlike on glass, no clear evidence was found for electrostatic repulsion with stainless steel since high adhesion was observed whatever the ionic strength. A lack of correlation in adhesion results was also obtained when considering the surface physico-chemical characteristics of type I (hydrophilic) and type II (hydrophobic) rehydrated cells and those of both polymers. It was postulated that unavoidable “sticky” compounds were present on the cell wall, which could not be completely removed during the successive washings of the rehydrated cell suspension before use. This could dramatically alter the yeast surface properties and modify the adhesion strength, thus clearly demonstrating the necessity to work with yeast coming from fresh cultures. Biologically active yeast cells were then used. Once cultured, type I- and type II-yeast cells were shown to exhibit the same hydrophilic properties. Regardless of the material used, for the same ionic strength (150 mM NaCl), yeast adhesion was drastically reduced compared to rehydrated yeast cells. Among all the materials tested, the specificity of 316L stainless steel was clearly established. Indeed, for glass and polymers, cell adhesion was substratum-dependent and driven by the balance between the Lifshitz-van der Waals and Lewis acid/base interactions. Despite nearly identical surface free energies for polystyrene and stainless steel, the metallic surface promoted a totally distinct behaviour which was characterized by a strong – although highly variable – yeast adhesion.

Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants

The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied. The ability of rhamnolipid biosurfactant to inhibit adhesion of micro-organisms to silicone rubber was investigated in a parallel-plate flow chamber. The anti-adhesive activity of the biosurfactant at different concentrations was significant against all the strains and depended on the micro-organism tested. The results showed an effective reduction in the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all micro-organisms tested at the 4 g l(-1) undiluted rhamnolipid solution. Maximum initial reduction of adhesion rate (an average of 66%) occurred for Streptococcus salivarius GB 24/9 and Candida tropicalis GB 9/9. The number of cells adhering after 4 h on silicone rubber conditioned with biosurfactant was reduced to 48% for Staphylococcus epidermidis GB 9/6, Strep. salivarius GB 24/9, Staphylococcus aureus GB 2/1 and C. tropicalis GB 9/9 in comparison to controls. Perfusing the flow chamber with biosurfactant containing solution followed by the passage of a liquid-air interface, to investigate detachment of micro-organisms adhering to silicone rubber, produced high detachment (96%) of adhered cells for all micro-organisms studied, except for Staph. aureus GB 2/1 (67%). It is concluded that biosurfactant represent suitable compounds that should be considered in developing future strategies to prevent the microbial colonization of silicone rubber voice prostheses.

In vitro adhesion of Candida species to denture base materials

Adhesion of Candida species to prosthetic acrylic resins is an essential first step in the pathogenesis of denture stomatitis. Data on the relative adhesion of pathogenic non-albicans Candida species to different denture base materials are sparse. The purpose of the present study was to investigate in vitro adhesion of C. albicans, C. glabrata, C. krusei and C. dubliniensis to four different denture base materials. Specimens of both heat-cured resins (Vertex(TM) Rapid Simplified and ProBase Hot) and cold-cured resins (Paladur A and Paladur B) were prepared using a novel method and the adhesion of four strains each of the foregoing Candida species evaluated microscopically using a soft imaging system. There was a significant difference in yeast adherence between Vertex and the other resins. Only C. glabrata attached to Vertex, while all the remainder of the tested species adhered to all other resins tested except ProBase, which resisted C. krusei adhesion. There was a significant difference in candidal adhesion between cold-cured and heat-cured resins for three Candida species (C. albicans, P = 0.039; C. glabrata, P = 0.002 and C. krusei, P = 0.000). The type of denture base material and whether they are heat-cured or cold-cured play an important role in modifying candidal adhesion.