The effects of hexetidine (Oraldene) on the adherence of Candida albicans to human buccal epithelial cells in vitro and ex vivo and on in vitro morphogenesis.

Abstract

This study reports the effects of hexetidine (Oraldene) on two virulence attributes of Candida albicans, namely, in vitro and ex vivo adherence of yeast cells to buccal epithelial cells (BEC) and in vitro morphogenesis. The effects of hexetidine treatment of either yeast cells (stationary and exponential phases) or BEC on Candidal adherence, in terms of viable and non-viable adherent yeast cells, were evaluated using an acridine orange stain in conjunction with fluorescence microscopy. Ex vivo anti-adherence effects were determined by rinsing BEC in vivo with hexetidine (0.1%), removal of BEC after defined periods and inclusion in the adherence assay. The effects of hexetidine on morphogenesis were evaluated using light microscopy. Yeast cell viability following exposure to a range of concentration of hexetidine (0.005-0.1% v/v) for defined periods was determined following serial dilution and enumeration on solid media. Treatment of stationary and exponential phase yeast cells or BEC with hexetidine (0.1%) for a range of times (10-300 s) or, alternatively, with a range of concentrations of hexetidine (0.005-0.1%) for a fixed time (30s) significantly decreased the resultant Candidal/ epithelial adhesion. No correlations were observed between reduced adherence and either time of treatment or hexetidine concentration. In vivo treatment of BEC with hexetidine (0.1%) for 30s resulted in prolonged and significant reductions in the ex vivo adherence of both viable and non-viable yeast cells for periods of up to (and including) four hours post-rinsing. Treatment of C. albicans blastospores with hexetidine (0.05, 0.1% v/v) for 10s and 30s totally inhibited Candida morphogenesis, whereas treatment with lower antiseptic concentrations significantly reduced the extent of Candida morphogenesis and the rate of hyphal development. The effects of hexetidine on yeast cell viability were both concentration and time-dependent. The reduced adherence of C. albicans to BEC and the modification or inhibition of morphogenesis following exposure to hexetidine suggests a clinical role for hexetidine in the prophylaxis of both superficial candidosis and the systemic complications resulting from invasion of sub-epithelial tissue.