Effect of sub-inhibitory concentrations of antifungal drugs on adherence of Candida species

The adherence of three Candida species to human buccal epithelial cells (BECs) following treatment of the yeast with sub-inhibitory concentrations of amphotericin B, nystatin, miconazole nitrate, 5-fluorocytosine, octenidine and pirtenidine was investigated in vitro. Pre-incubation of C. albicans (two strains), C. tropicalis or C.kefyr with these antifungal drugs inhibited their adherence to varying degrees (reduction between 17% and 78% of the control value). Pre-treatment of yeast for a short period (l hr) had less effect on adhesion than pre-treatment for a long period (24 hr). Furthermore, treating C. albicans with a combination of amphotericin B plus 5-fluorocytosine, both at 1/8 MIC level, led to stronger adherence inhibition than that obtained for yeast pre-treated with either one alone at 1/4 MIC levels. In addition, the pre-treatment of either Candida or BECs or both types of cells with the drugs reduced adherence, the reduction being greatest when both types of cells were pre-treated. No difference in adherence between stationary or exponential phase yeast to BEC was observed and the drugs were effective in reducing the adherence of cells from either growth phase. [Continues.]