Monoclonal antibody-mediated inhibition of adhesion of Candida albicans and Candida dubliniensis to human epithelial cells

The aim of this study was to assess the role of whole saliva, four saliva-derived preparations, and six monoclonal antibodies (mAbs), directed against components of the cell wall of Candida albicans , on the adhesion of C. albicans and Candida dubliniensis to human epithelial cells (HEC). C. albicans serotype A NCPF 3153 and C. albicans serotype B ATCC 90028 showed higher adhesion to HEC than C. dubliniensis NCPF 3949. Pooled whole saliva was more efficient than salivary secretory immunoglobulin A, partially purified by chromatography, at inhibiting the adhesion of C. albicans serotype A NCPF 3153 to HEC. Monoclonal antibodies C7, 14-8, and 26G7 were the most potent inhibitors of adhesion. Our results show that mAbs can mimic the inhibition of adhesion of C. albicans to HEC that is mediated by human saliva.     

Candida albicans adherence to resin-composite restorative dental material: influence of whole human saliva

OBJECTIVE: Attachment of Candida albicans to oral surfaces is believed to be a critical event in the colonization of the oral cavity and in the development of oral diseases such as Candida-associated denture stomatitis. Although there is considerable information about the adhesion of C albicans to buccal epithelial cells and prosthetic materials, there is very little information about the adhesion of C albicans to composite restorative materials. The purpose of this study was to investigate the degree of adhesion of C albicans to a resin-composite restorative material (Herculite). METHODS: The adhesion of 2 strains of C albicans, a germinative and a germ tube-deficient mutant, was studied by a visual method after incubating the fungus and the resin with and without human whole saliva. RESULTS: In absence of saliva, the adhesion of the C albicans germinative isolate to the resin showed an increase in parallel with the germination, reaching a maximum at the end of the experiment (120 minutes). However, no significant differences were observed in the adhesion of the agerminative mutant during the period of time studied. In the presence of saliva, the adhesion of both isolates to the resin was significantly lowered. CONCLUSION: Germination and the presence of human whole saliva are important factors in the adhesion of C albicans to the resin-composite restorative material Herculite.     

Saliva promotes Candida albicans adherence to human epithelial cells

Adhesion of Candida cells to oral surfaces is an initial event in pathogenesis. Since specific immobilized salivary components mediate the binding of Candida albicans to hydroxyapatite, we hypothesized that saliva may also promote adherence to oral epithelia via a similar mechanism. In an in vitro model, C. albicans ATCC 10261 yeast cells adhered in a saturable manner to monolayers of three cultured human epithelial cell lines (A549, HEp-2, and HET-1A). The addition of whole saliva to the assay promoted the binding of C. albicans to all cell lines in a dose-dependent manner, but pre-incubation of the epithelial cells with pooled whole saliva had no effect on subsequent adherence. Pre-incubation of the yeast cells with pooled whole saliva, however, significantly enhanced (by up to 120%, P < 0.05) binding to epithelial cell monolayers, and pooled saliva that had been pre-incubated with C. albicans yeast cells was defective in promoting yeast adherence. There was a negative correlation (r = 0.68, P < 0.005) between specific IgA titers against whole cells of C. albicans and adherence-promoting activities for individual saliva samples. The adhesion-inhibitory effect of specific anti-C. albicans IgA was reversed by depletion of IgA from saliva by affinity chromatography. Factors in whole saliva, therefore, bound to the yeast cells, counter the C. albicans-specific salivary IgA inhibitory effect on adhesion and promote the adherence of C. albicans yeast cells to cultured epithelial cells.     

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

STATEMENT OF PROBLEM: 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. PURPOSE: This study evaluated the influence of polymerization methods and human whole saliva on the adherence of Candida species to acrylic resin surfaces. MATERIAL AND METHODS: 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). RESULTS: 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). CONCLUSION: 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. CLINICAL IMPLICATIONS: 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.     

Candida albicans binds to saliva proteins selectively adsorbed to silicone

Explanted voice prostheses obtained from 5 patients at the time of prosthesis replacement were consistently colonized by yeast, in particular Candida albicans. A simple, reproducible, in vitro model of C. albicans adherence to saliva-coated voice prosthesis silicone was developed. Whole saliva promoted adherence of C. albicans to silicone in a dose-dependent manner. Saliva rinses from voice prosthesis patients also promoted binding of C. albicans to silicone in vitro (mean adherence 14.9% +/- 2.8% of input C. albicans cells). This was significantly higher than C. albicans adherence to silicone in the absence of saliva (P < .001) or adherence promoted by saliva rinses from healthy volunteers (P < .005). Polyacrylamide gel electrophoresis analysis and a blot overlay adherence assay revealed that certain salivary proteins were selectively adsorbed to silicone and that C. albicans yeast cells adhered specifically to the adsorbed salivary proteins.     

Adhesion of Candida albicans, but not Candida krusei, to salivary statherin and mimicking host molecules

The aim of the present study was to identify salivary molecules affecting adhesion of Candida albicans and Candida krusei to salivary pellicles and epithelial cells. Strains of C. albicans (GDH18, GDH3339, CA1957, ATCC 28366 and ATCC 10321), but not C. krusei (strains ATCC 14243 and Ck9), bound to saliva-coated hydroxyapatite and buccal epithelial cells. Parotid saliva fractions containing statherin, glycosylated proline-rich proteins (PRP) and as yet unidentified components mediated adhesion of strain GDH18; Fuc alpha 1-2Gal beta 1-4Glc partly inhibited the adhesion to those fractions not containing statherin. Pure statherin, but not PRP-1, mediated dose-dependent adhesion of C. albicans strain GDH18 to hydroxyapatite beads. Candida isolates (GDH18, GDH3339 and CA1957) bound somewhat more avidly to statherin/saliva relative to ATCC strains 28366 and 10321, while the opposite was true for adhesion to buccal epithelial cells. Adhesion of C. albicans strain GDH18 to saliva-coated hydroxyapatite and buccal epithelial cells was completely (93%) and partly (43%) blocked by statherin-specific immunoglobulin G (IgG) antibodies, respectively. Control IgG antibodies did not block Candida adhesion. Blockage of Candida adhesion to epithelial cells also occurred with Fuc alpha 1-2Gal beta 1-4Glc (49%) and N-acetylglucosamine (38%), while statherin specific IgG antibodies in combination with Fuc alpha 1-2Gal beta 1-4Glc almost completely eliminated Candida adhesion (79%). In addition, statherin in solution blocked the adhesion of strain GDH18 to epithelial cells by inducing aggregation of Candida cells.     

Effect of saliva composition on growth of Candida albicans and Torulopsis glabrata

Candida albicans and Torulopsis glabrata are the most prevalent yeasts in humans. The majority harbor C. albicans in the oral cavity, but only a few develop oral candidiasis. We have sought a possible relationship between indigenous salivary constituents, including antimicrobial and nutritive factors, and the growth rate and/or viability of inoculated fungi in glucose-supplemented sterilized saliva. Stimulated whole saliva was collected from 30 healthy donors. Saliva samples were sterilized, supplemented with glucose and inoculated with C. albicans or T. glabrata . After incubation of the inoculates for 20 h, the number of viable cells were counted. All saliva samples were analyzed for different indigenous salivary components and Candida before as well as after sterilization. Besides a 4% reduction in calcium (Ca²⁺) and thiocyanate (SCN⁻) concentrations, sterilization did not affect the concentrations of saliva electrolytes, but the proteins were significantly reduced (19–85%). Indigenous candidal carriage ( n =19) correlated with neither the growth of inoculated fungi nor any of the analyzed components in saliva. The growth of C. albicans and T. glabrata was similar at pH 5 but, at pH 6, C. albicans had a remarkably slower growth rate than T. glabrata . Statistical analysis showed that the 5-h growth of C. albicans at pH 5 was associated with water and electrolyte secretion, whereas the growth after 20 h was associated with variations in protein-glycoprotein content. The growth of T. glabrata was not related to variations in the salivary variables analyzed.     

Influence of environmental pH on the reactivity of Candida albicans with salivary IgA

Salivary secretory IgA reacts with a group of heat-shock mannoproteins preferentially expressed on Candida albicans yeast cells and germ tubes grown at 37 degrees C. Since other environmental factors can also modulate the expression of those antigens, we have investigated the influence of the pH of the culture medium on the expression of the antigens reacting with human salivary IgA by C. albicans. By indirect immunofluorescence, yeast cells grown in Sabouraud glucose broth at 37 degrees C showed a statistically significant increase in reactivity with salivary IgA (p < 0.0001) when compared with cells grown at 25 degrees C at the 4 pH values studied (3.3, 5.9, 7.5, and 9.5), the highest reactivity and the major heat-shock effect being observed at pH 5.9. The decrease in reactivity with salivary IgA observed in C. albicans cells grown at pH values of 3.3 and 9.5 was confirmed by Western blotting. Salivary IgA reacted with polydispersed materials from the cell walls of molecular masses > 55 kDa, which were more expressed at neutral pH than at acidic or alkaline pH values. A similar reactivity was observed when the antigenic extracts were stained with an antiserum directed against oligosaccharides present in antigen 6 of C. albicans serotype A. The differences in reactivity presented by salivary IgA may be related to a decrease in the expression of polysaccharides present on the surfaces of the yeast cells of C. albicans grown at acidic or alkaline pH values. The low reactivity of salivary IgA with C. albicans cells grown at acidic pH values may help to explain the association between acidic saliva and the carriage of Candida in the oral cavity, as well as with oral candidiasis.     

The influence of morphological variation on Candida albicans adhesion to denture acrylic in vitro.

Using denture acrylic pieces coated with either whole human stimulated saliva or oral streptococci, the binding ability of three different Candida albicans strains was investigated. The C. albicans strains include a clinical isolate with the commonly observed, smooth, round colonial morphology (strain 613p), a morphological variant spontaneously derived from the clinical isolate strain 613p (strain 613m1BK) and a clinical isolate from an oral lesion that was also a morphological variant upon primary isolation (strain 228). Levels of adhesion to the acrylic pieces were determined radiometrically using C. albicans cells metabolically labelled with [35S]-methionine. Whole stimulated saliva significantly increased the binding of all strains compared to uncoated acrylic. However, the level of binding of strain 613p to saliva-coated acrylic was significantly greater than the levels observed for the morphological variant strain 613m1BK. Coating acrylic pieces with either Streptococcus sanguis NCTC 10904, Strep. mutans GS-5 or Strep. sobrinus ATCC 27352 instead of saliva resulted in significantly greater binding by strain 613p compared to uncoated acrylic. Pre-coating the acrylic with the oral streptococci did not significantly increase the binding of morphological variant strains 613m1BK and 228 compared to uncoated acrylic. In general, preincubation of adherent streptococci with sucrose to induce the synthesis of extracellular carbohydrate polymers did not significantly increase the binding levels of the C. albicans strains above those observed using streptococci in buffer alone. Compared to its parental strain 613p, morphological variant strain 613m1BK adhered poorly to denture acrylic coated with either salivary constituents or oral streptococci, while strain 228 adhered to the same substrates at an intermediate level. Furthermore, physical disaggregation of clusters of the morphological variant strain 613m1BK did not appear to increase its binding capacity to saliva-coated denture acrylic. The effect of whole stimulated saliva on the adherence of C. albicans 613p to a variety of plastic substrates in addition to denture acrylic was examined. Overall, saliva pre-coating of the various plastics promoted C. albicans 613p adhesion. The adhesion of strain 613p to denture acrylic coated with whole stimulated saliva from each of five different donors or with parotid and submandibular/sublingual saliva from each of two donors was also examined. Regardless of donor, a coating of whole stimulated saliva significantly increased the binding of strain 613p to denture acrylic compared to uncoated acrylic. In addition, a coating of parotid saliva significantly increased the binding of strain 613p to denture acrylic compared to submandibular/sublingual saliva.     

Modification of adherence to plastic and to human buccal cells of Candida albicans and Candida dubliniensis by a subinhibitory concentration of itraconazole

Exposure to subinhibitory concentrations of antifungal agents can influence the adherence of Candida spp. to the host cell. In this study the adherence of Candida albicans ATCC 10231 and Candida dubliniensis CECT 11455 to plastic and to human buccal epithelial cells was evaluated following pre-exposure to 0.5 x minimum inhibitory capacity (MIC) of itraconazole and compared with the corresponding cellular surface hydrophobicity. The yeasts were grown in Sabouraud broth or RPMI-1640 with itraconazole (0.5 x MIC) for 24-26 h at 37 degrees C and the drug was then removed. The adhesion capacity to plastic was studied by turbidimetry in a polystyrene microtiter plate. The adhesion of the yeast to buccal epithelial cells was determined using microscopy techniques. The cellular surface hydrophobicity levels were determined by the microbial adhesion hydrocarbons test. Pre-exposure to itraconazole decreased plastic adherence and cellular surface hydrophobicity in both species when grown in RPMI. When C. albicans was grown in Sabouraud broth, it was nonhydrophobic and did not adhere and therefore no change was detected with the antibiotic. Itraconazole increased adherence to buccal epithelial cells in both species and media studied, as compared to controls without antifungal agents. To study the effects of these antifungal agents on pathogenicity mechanisms, it will be necessary to standardize the methodology for evaluation to determine their in vivo therapeutic efficacy.     

Surface roughness and adherence of Candida albicans on soft lining materials as influenced by accelerated aging

AIM: Candida albicans (C. albicans) has been widely associated with the etiology of denture-related stomatitis and has been found on soft denture lining materials. The aim of this study was to examine the surface roughness and adherence of C. albicans to saliva coated and non-coated soft lining materials by subjecting them to an in vitro accelerated aging test. METHODS AND MATERIALS: Samples were prepared from three soft lining materials (Visco Gel, Ufi Gel P, Molloplast B). Surface roughness measurements and adhesion of C. albicans were examined before and after an aging process. The stimulated human whole saliva was used to assess its effect on adhesion. RESULTS: The aging process promotes the surface roughness of soft lining materials. The aging surface roughness of Visco Gel was significantly higher than Ufi Gel P and Molloplast B. No significant difference was observed between non-aged and uncoated materials, but aged and uncoated soft lining materials showed a greater adherence of C. albicans. No significant difference was observed between non-aged and saliva coated materials, but aged and saliva coated soft lining materials showed a greater adherence of C. albicans. CONCLUSIONS: Candidosis induced by C. albicans is the most common fungal infection. Awareness of susceptibility of soft lining materials to the adherence of C. albicans is an important factor in their selection. The use of soft lining materials with smooth surfaces minimizes the adherence of C. albicans.     

Adhesion of oral Candida species to human buccal epithelial cells following brief exposure to nystatin

Opportunistic oral infections caused by Candida albicans and non-albicans Candida species are particularly common in compromised patients. Nystatin, which belongs to the polyene group of antimycotics, is frequently used as a topical agent in the treatment of oro-pharyngeal candidosis. It is recognized that due to the delivery mode of nystatin (i.e. topical, intermittent), as well as the cleansing effect of saliva within the oral environment, the yeasts undergo a relatively brief exposure to this drug during treatment. Nevertheless, there is a sparsity of data on the effect of such brief exposure to nystatin on the pathogenic attributes of Candida such as their adherence to host surfaces. The adhesion of microbes to host mucosal surfaces is a major determinant of successful colonization and infection. Thus the main aim of our investigation was to compare the in vitro adhesion of 30 oral isolates of Candida belonging to six different species (comprising Candida albicans, Candida tropicalis, Candida glabrata, Candida guilliermondii, Candida krusei and Candida parapsilosis) to human buccal epithelial cells, following their brief exposure (1 h) to minimum inhibitory concentration of nystatin, and subsequent removal of the drug. The adhesion of these isolates to buccal epithelial cells was assessed by a previously described adhesion assay. Compared with the controls, there was a significant reduction in buccal epithelial cell adhesion of all six Candida species after drug exposure (54%-68%). However the adhesion of C. albicans isolates was the least affected by nystatin exposure, which was significantly different from that of the non-albicans species. These findings imply that sub-therapeutic levels of nystatin, which are likely to persist in the oral cavity during dosing intervals, may also be beneficial, as they inhibit candidal colonization. The significant difference in nystatin-induced suppression of adhesion between C. albicans and the non-albicans species investigated is a further testimonial for the pre-eminent virulence of the former species.     

Rapid and unequivocal differentiation of Candida dubliniensis from other Candida species using species-specific DNA probes: comparison with phenotypic identification methods

Candida dubliniensis is a recently described opportunistic pathogen which shares many phenotypic characteristics with Candida albicans but which has been reported to rapidly acquire resistance to azole antifungal drugs. Therefore, differentiation of C. dubliniensis from C. albicans becomes important to better understand the clinical significance and epidemiologic role of C. dubliniensis in candidiasis. We compared phenotypic methods for the differentiation of C. dubliniensis from C. albicans (i.e. the ability to grow at elevated temperatures, colony color on CHROMagar Candida medium, and carbohydrate assimilation patterns) to amplify the results of a polymerase chain reaction (PCR) assay using universal fungal primers to the internal transcribed spacer 2 (ITS2) region of rDNA and species-specific DNA probes in an enzyme immunoassay format (PCR-EIA). DNA sequencing of the ITS1 rDNA region was also conducted. The C. dubliniensis ITS2 probe correctly identified all C. dubliniensis isolates without cross-reaction with any other Candida species tested (mean A(650 nm) +/- SE, C. dubliniensis probe with C. dubliniensis DNA, 0.372 +/- 0.01, n = 22; C. dubliniensis probe with other Candida species DNA, 0.001 +/- 0.02 n = 16, P < 0.001). All other Candida species tested (C. albicans, Candida glabrata, Candida krusei, Candida parapsilosis, and Candida tropicalis) were also correctly identified by the PCR-EIA without any detectable cross-reactions among species. Phenotypically, C. dubliniensis isolates demonstrated an increased sensitivity to heat compared to C. albicans isolates. At 42 degrees C, only 50% of C. dubliniensis isolates grew compared to 73% of C. albicans isolates and, at 45 degrees C, 91% of C. dubliniensis isolates failed to grow compared to 64% of C. albicans isolates. C. albicans was more likely to demonstrate a dark green or blue green colony color on CHROMagar Candida medium obtained from Becton Dickinson (i.e. 100% of C. albicans isolates were dark green or blue green versus 64% of C. dubliniensis isolates) whereas no difference in the percentage of C. albicans or C. dubliniensis isolates producing dark green or blue green colony color was detected using CHROMagar Candida medium from Hardy Diagnostics (82% for both species). The API 20C AUX carbohydrate assimilation system incorrectly identified C. dubliniensis as C. albicans in all but three cases: remaining isolates were misidentified as C. albicans/C. tropicalis, C. tropicalis/C. albicans, and Candida lusitaniae/C. albicans. In all, 82% of C. albicans isolates and 100% of C. dubliniensis isolates assimilated trehalose; the latter finding was opposite to that reported for C. dubliniensis in the API 20C AUX profile index. Xylose and alpha-methyl-D-glucoside assimilation, respectively, were negative for 100 and 95% of C. dubliniensis isolates and positive for 100 and 91% of C. albicans isolates, confirming earlier reports that assimilation results for xylose and alpha-methyl-D-glucoside may be helpful in the discrimination of these two species. However, conventional phenotypic species identification tests required days for completion, whereas the PCR-EIA could be completed in a matter of hours. In addition, identification of Candida species by ITS1 rDNA sequencing gave 100% correspondence to the results obtained by the PCR-EIA, confirming the specificity of the PCR-EIA method. These data indicate that although a combination of phenotypic methods may help differentiate C. dubliniensis from C. albicans to some extent, the PCR-EIA can provide a simple, rapid, and unequivocal identification of the most medically important Candida species in a single test.     

In vitro antifungal effect of amine fluoride-stannous fluoride combination on oral Candida species

OBJECTIVE: The combination of amine fluoride and stannous fluoride (AmF/SnF2) was, by chance, found to be antifungal in a clinical trial. This study investigated its effect on pathogenic Candida species with the hypothesis that the antifungal action on different species is variable. MATERIALS AND METHODS: Growth inhibition effect of Meridol mouth rinse which contains 250 ppm AmF/SnF2 was evaluated on 43 reference and clinical strains of Candida albicans, C. dubliniensis, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. Meridol base solution without AmF/SnF2 was used as a negative control. RESULTS: Undiluted Meridolmouth rinse killed most study strains within a few minutes. In ascending order, C. parapsilosis, C. tropicalis, C. albicans, C. glabrata, C. krusei and C. dubliniensis showed higher resistance against AmF/SnF2 than C. guilliermondii. CONCLUSION: AmF/SnF2 could be used as a potent adjunct to antifungal therapy for oral yeasts. Although different Candida species demonstrated variable sensitivity the most prevalent oral yeast C. albicans appeared sensitive to the AmF/SnF2 combination.     

Biofilm formation of Candida albicans is variably affected by saliva and dietary sugars

The pathogenesis of both superficial and systemic candidiasis is closely dictated by properties of the yeast biofilms. Despite extensive investigations on bacterial biofilms, the characteristics of candidal biofilms, and various factors affecting this process remain to be determined. Therefore we examined the effect of human whole saliva and dietary sugars, glucose and galactose on the adhesion and biofilm formation of Candida albicans. Biofilms of C. albicans isolate 192 887 g were developed on polystyrene, flat-bottomed 96-well microtiter plates and monitored using ATP bioluminescence and tetrazolium (XTT) reduction assays as well as the conventional colony forming unit (CFU) evaluation. Our data showed that both the ATP and the XTT assays strongly correlated with the CFU assay (ATP versus CFU: r = 0.994, P = 0.006; XTT versus CFU: r = 0.985, P = 0.015). Compared with a glucose-supplemented (100 mM) medium, galactose containing (500 mM) medium generated consistently lower levels of both candidal adhesion and biofilm formation (all P < 0.05), but a higher pace of biofilm development over time (96 h). Whist the presence of an immobilised saliva coating had little effect on either the candidal adhesion or biofilm formation, the addition of saliva to the incubation medium quantitatively affected biofilm formation especially on day 3 and 4, without any significant effect on yeast adhesion. To conclude, biofilm formation of C. albicans within the oral milieu appears to be modulated to varying extents by dietary and salivary factors and, further investigations are required to elucidate these complex interactions.     

白色念珠菌在渗透陶瓷表面黏附性的研究

目的研究白色念珠菌在渗透陶瓷表面黏附的影响因素.方法将白色念珠菌黏附在渗透陶瓷和熔附式烤瓷两种修复材料表面,并对材料表面的白色念珠菌黏附数量进行计数,统计分析.结果在唾液获得膜存在和不存在的两种条件下,渗透陶瓷和熔附式烤瓷材料表面的白色念珠菌数量无显著性差异(P＞0.05),而在有唾液获得膜存在的条件下,白色念珠菌在两种材料表面的黏附数量显著低于无唾液获得膜存在时(P＜0.05).结论两种修复材料表面存在白色念珠菌的黏附现象且具有相似性、低黏附性,唾液获得膜的存在可降低白色念珠菌的黏附.     

The in vitro proteolytic and saccharolytic activity of Candida species cultured in human saliva

The proteolytic and saccharolytic activity of 4 Candida species was investigated in batch cultures of pooled, human mixed saliva supplemented with glucose. All the Candida species investigated ( Candida albicans, Candida tropicalis, Candida glabrata and Candida krusei ) demonstrated a marked growth in saliva with a concomitant reduction in pH from about 7.5 to 3.3, within 72 h. Isotachophoretic analysis of the culture supernatant revealed the presence of a variety of acid anions of which pyruvate and acetate were the most abundant. Proteolysis of salivary components, evaluated by a biochemical assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was exhibited by all 4 Candida species, although there was inter-species variation. Despite the similarity in growth rates, C. tropicalis and C. krusei demonstrated greater proteolytic activity than C. albicans and C. glabrata. Neither candidal growth nor proteolysis was observed in glucose-free control saliva samples. In contrast, the degree of saccharolytic and proteolytic activity of a single isolate of C. albicans in glucose-supplemented parotid saliva appeared to be relatively weak compared with mixed saliva. As the oral cavity provides ideal low pH niches periodically supplemented with dietary carbohydrates, the acidic proteinases of Candida species may play a role in the pathogenesis of oral candidiasis.     

The relationship between oral Candida carriage and the secretor status of blood group antigens in saliva

OBJECTIVE: The aim of the study was to investigate the relationship between oral Candida carriage and the secretor status of blood group antigens. STUDY DESIGN: Unstimulated whole saliva and oral rinse samples were obtained from 180 healthy subjects. These samples were plated on Sabouraud's dextrose agar media to determine oral Candida carriage. Sodium dodecylsulfate polyacrylamide gel electrophoresis and immunoblotting were performed on whole saliva samples to determine the secretor status of blood group antigens. RESULTS: The oral Candida carriage rate was found to be 45.0%. The sensitivity of the concentrated rinse culture proved to be superior. Oral Candida carriage was not significantly related to the blood group or secretor status of ABH or Lewis antigens. No significant relationship was found between oral Candida carriage and salivary flow rate. However, smoking affected oral Candida carriage. CONCLUSION: Oral Candida carriage in healthy individuals is not significantly related to blood group or secretor status.     

Identification of Candida dubliniensis among oral yeast isolates from an Italian population of human immunodeficiency virus-infected (HIV+) subjects

Candida dubliniensis, an emerging oral pathogen, phenotypically resembles Candida albicans so closely that it is easily misidentified as such. The aim of the present study was to evaluate the usefulness of two phenotypic methods, growth at 45 degrees C and 2,3,5-triphenyltetrazolium chloride (TTC) reduction, for confirming presumptive identification of C. dubliniensis and C. albicans by colony color on CHROMagar Candida (CAC) medium. A combination of these methods was used to establish the prevalence of oral C. dubliniensis in an Italian population of 45 human immunodeficiency virus (HIV)-infected subjects. Twenty-two samples (48.9%) were positive for yeasts on CAC medium producing a total of 37 fungal isolates. The colony color and 45 degrees C growth ability test correctly identified all C. dubliniensis and C. albicans isolates (5/37, 13.5%, and 16/37, 43.2%, respectively), while assessment of TTC reduction misidentified one C. albicans isolate. The isolation rate of C. dubliniensis was 11.1% (5/45 patients). All of the C. dubliniensis isolates were highly susceptible to fluconazole (MIC = 0.5 microg/ml). The combination of CAC medium screening with growth at 45 degrees C and TTC reduction tests may represent a simple, reliable and inexpensive identification protocol for C. dubliniensis.     

Candida dubliniensis in radiation-induced oropharyngeal candidiasis

Candida dubliniensis is a recently described species that has been shown to cause oropharyngeal candidiasis in patients with HIV. We present a detailed evaluation of a patient undergoing head and neck radiation for oral cancer who developed oropharyngeal candidiasis from a mixed infection of C dubliniensis and Candida albicans. To our knowledge, this is the first described case of C dubliniensis contributing to oropharyngeal candidiasis in this patient population.