The Effect of PMMA/Hydroxyapatite Adsorbed Salivary Proteins on C. albicans

The limited number of treatments for oral candidiasis resulted in the emergence of azole-resistant C. albicans strains, thus enforcing the need for novel antifungal treatments. Although histatin 5 (H5) demonstrates antifungal activity, its inhibitory effect when adhered to oral surfaces, resembling conditions of the in vivo pellicle, remains unexplored. Objectives: We aim to investigate the antifungal effect of H5 when it is adhered to PMMA and hydroxyapatite surfaces throughout a series of time intervals. Methods: Our biofilm assay involved developing monolayer protein integument (either H5 or albumin) on hydroxyapatite and PMMA discs, introducing C. albicans to this model system, and counting the number of adhered cells, throughout time, using scanning electron microscopy. Results: H5-coated-PMMA had significantly reduced number of cells compared to albumin-coated-PMMA at 30, 90, and 1440 minutes (p<0.0001), with the number of cells decreasing significantly across 90 and 1440 minutes (p<0.0001). Similarly, H5-coated-hydroxyapatite had significantly less cells compared to the albumin-coated surface at 90 and 1440 minutes (p<0.0001), with the number of cells decreasing significantly across 30, 90, and 1440 minutes (p<0.0001). The antifungal effect of PMMA and hydroxyapatite adhered H5 was strongest at 24 hours of biofilm maturation. In addition, cocci cells colonized albumin-coated-PMMA, while dense hyphael networks predominately colonized albumin-coated-hydroxyapatite. Conclusion: H5 maintains its, time-dependent, antifungal activity when adhered as a monolayer protein to PMMA and hydroxyapatite. Furthermore, C. albicans morphological plasticity may be influenced by the surface available for albumin adhesion.