Abstract

Background
Candida biofilms with reduced susceptibility to conventional antifungals are sensitive to lipid formulations of amphotericin B (AMB). We examined the effect of the liposomal AMB formulation, AmBisome, and free AMB on the adherence of C. albicans to HeLa cervical carcinoma and HSC-3 oral squamous cell carcinoma cells.
Material and Method
HeLa and HSC-3 cells were incubated with three oral isolates of C. albicans either in the presence of AmBisome or AMB, or pre-incubated with yeasts and subsequently exposed to the drug. The effect of the drugs on the viability of HeLa and HSC-3 cells was determined by an Alamar Blue assay.
Results
Following a 1-h incubation in the presence of AmBisome, at 1-256 microg/ml, the adherence of C. albicans to HeLa and HSC-3 cells was reduced considerably. For example at 16 microg/ml, adherence was diminished by approximately 66% in HeLa and by approximately 36% in HSC-3 cells. The susceptibility of cell-associated Candida to antifungals was decreased markedly. The reduction in adherence was between 3.3 and 13.7%, when compared to the drug-free controls. AmBisome was not toxic in the range 1-256 microg/ml, while free AMB was not toxic at 1 and 4 microg/ml to HeLa cells and at 1, 4 and 16 microg/ml to HSC-3 cells.
Conclusions
AmBisome inhibited candidal attachment when present during the "adherence phase" but did not cause detachment of cell-associated yeasts. The effect of AmBisome on candidal adherence to HSC-3 cells was less inhibitory than that observed with HeLa cells. Candidal adherence to epithelial cells is significantly reduced when antifungal polyenes are present during the "adherence phase", while cell-associated Candida is resistant to antifungals in terms of adherence.

Keywords: Epithelial Cells - microbiology, Cell Survival - drug effects, Candida albicans - metabolism, Cell Adhesion - drug effects, Biofilms, Antifungal Agents - pharmacology, Amphotericin B - pharmacology