The effect of histatin 5, adsorbed on PMMA and hydroxyapatite, on Candida albicans colonization

Abstract

The limited number of treatments for oral candidiasis resulted in the emergence of azole-resistant Candida albicans strains, thus enforcing the need for novel antifungal treatments. Although histatin 5 (H5) demonstrates antifungal activity, its inhibitory effect when adhered to hydroxyapatite and Polymetylmethacrylate (PMMA) surfaces, resembling conditions of the in vivo pellicle, remains unexplored. The objective of this in vitro study was to determine whether surface-adhered H5 inhibits the colonization of C. albicans on hydroxyapatite and/or PMMA. The C. albicans assay involved developing a mono-protein pellicle (either H5 or albumin) on hydroxyapatite and PMMA discs, introducing C. albicans and counting the number of adhered cells, throughout time, using scanning electron microscopy. A negative binomial statistical model and the Tukey-Kramer test were used for statistical analysis, with p < 0.01 indicating significance. H5-coated PMMA had significantly reduced number of cells compared to albumin-coated PMMA at 30, 90 and 1440 min (p < 0.0001), with the number of cells decreasing significantly in 90 and 1440 min (p < 0.0001). Similarly, H5-coated hydroxyapatite had significantly fewer cells compared to the albumin-coated surface at 90 and 1440 min (p < 0.0001), with the number of cells decreasing significantly at 30, 90 and 1440 min (p < 0.0001). In conclusion, C. albicans colonization was most inhibited by PMMA and hydroxyapatite-adhered H5 after 1440 min, illustrating the time-dependent effect of H5. In addition, yeast cells colonized albumin-coated PMMA, while dense hyphal networks formed on albumin-coated hydroxyapatite, suggesting that C. albicans morphology is influenced by the surface available for albumin adhesion.