In vitro effect of amphotericin B on Candida albicans, Candida glabrata and Candida parapsilosis biofilm formation.

Candida spp. biofilm is considered highly resistant to conventional antifungals. The aim of this study was to investigate the in vitro effect of amphotericin B on Candida spp. biofilms at different stages of maturation. We investigated the activity of amphotericin B against 78 clinical isolates of Candida spp., representing three species, growing as planktonic and sessile cells, by a widely accepted broth microdilution method. The in vitro effect on sessile cell viability was evaluated by MTT reduction assay. All examined strains were susceptible to amphotericin B when grown as free-living cells. At the early stages of biofilm maturation 96.7-100.0 % strains, depending on species, displayed amphotericin B sessile minimal inhibitory concentration (SMIC) ≤ 1 μg/mL. Mature Candida spp. biofilm of 32.1-90.0 % strains displayed amphotericin B SMIC ≤ 1 μg/mL. Based on these results, amphotericin B displays species- and strain-depending activity against Candida spp. biofilms.