Surface modifying substances that reduce apparent yeast cell hydrophobicity

Cell surface hydrophobicity and colony morphology of Trichosporon asahii clinical isolates

Trichosporon asahii is a pathogenic basidiomycetous yeast. Individual strains of T. asahii have different colony morphologies. However, it is not clear whether cell surface phenotypes differ among the colony morphologies. Here we characterized the cell surface hydrophobicity and analysed the carbohydrate contents of the cell surface polysaccharides in T. asahii clinical isolates with various colony morphologies. Among the three distinctive colony morphologies obtained from one clinical isolate, the white-type morphology exhibited higher hydrophobicity. The hydrophobicity of heat-killed T. asahii cells was greatly reduced after periodate oxidation of the cell surface carbohydrates. Furthermore, the cell wall and extracellular polysaccharide components differed among the morphologies. Our results suggest that T. asahii cell surface hydrophobicity is affected by cell surface carbohydrate composition. Copyright © 2016 John Wiley & Sons, Ltd.

Determination of biofilm production by Candida tropicalis isolated from hospitalized patients and its relation to cellular surface hydrophobicity, plastic adherence and filamentation ability

Candida tropicalis is an emerging virulent species. The aim of this study is to determine the biofilm-forming ability of 29 strains of C. tropicalis isolated from inpatients, and to examine its relation with other virulence factors such as cellular surface hydrophobicity (CSH), immediate (15 min, IA) and late (24 h, LA) plastic adherence and filamentation ability. The study was performed in parallel using two incubation temperatures - 37 and 22 °C - to determine the effect of growth temperature variations on these pathogenic attributes of C. tropicalis. Biofilm formation (BF) was measured by optical density (OD) and by XTT reduction (XTT); Slime index (SI), which includes growth as a correction factor in BF, was calculated in both methods. All strains were hydrophobic and adherent - at 15 min and 24 h - at both temperatures, with higher values for 22 °C; the adhered basal yeast layer appears to be necessary to achieve subsequent development of biofilm. Filamentation ability varied from 76.2% of strains at 37 °C to 26.6% at 22 °C. All C. tropicalis strains were biofilm producers, with similar results obtained using OD determination and XTT measurement to evaluation methods; SI is useful when good growth is not presented. BF at 37 °C was similar at 24 h and 96 h incubation; conversely, at 22 °C, the highest number of biofilm-producing strains was detected at 96 h. CSH is an important pathogenic factor which is involved in adherence, is influenced by the filamentation of yeast, and plays a critical role in BF.

Systematic survey of nonspecific agglutination by Candida spp. in latex assays

In order to demonstrate that cells of Candida spp. may show considerable nonspecific agglutination in latex agglutination tests, 150 clinical and reference isolates of 12 yeast species were systematically studied by applying various test parameters. In fact, 40 (26.7%) of these isolates revealed nonspecific results, significantly associated with the time allowed for agglutination.

Adherence and blocking of Candida albicans to cultured vaginal epithelial cells: treatments to decrease adherence

BACKGROUND

Pathogenesis of mucosal microorganisms depends on adherence to the tissues they colonize and infect. For Candida albicans, cell surface hydrophobicity may play a significant role in tissue binding ability.

METHODS

A continuous cell line of vaginal epithelial cells (VEC) was grown in keratinocyte serum-free medium (KSFM) with supplements and harvested by trypsinization. VEC were combined with yeast cells to evaluate adherence and inhibition of adherence. In this experimental setup, yeast stained with fluorescein isothiocyanate were allowed to attach to VEC and the resulting fluorescent VEC were detected by flow cytometry.

RESULTS

VEC were cultured and examined daily after plating and showed morphology similar to basal epithelial cells. Culture media supplemented with estradiol showed increased VEC proliferation initially (first 24 h) but cell morphology was not altered. Fluorescinated Candida cells bound effectively to the cultured VEC. Using fresh cells exposed to various preparations of K-Y, we showed that all formulations of the product reduced Candida binding to VEC by 25% to 50%. While VEC were generally harvested for use in experiments when they were near confluent growth, we allowed some cultures to grow beyond that point and discovered that cells allowed to become overgrown or stressed appeared to bind yeast cells more effectively.

CONCLUSION

Flow cytometry is a useful method for evaluating binding of stained yeast cells to cultured VEC and has demonstrated that commercially available products have the ability to interfere with the process of yeast adherence to epithelial cells.