In vitro antifungal susceptibility pattern and ergosterol content in clinical yeast strains.

BACKGROUND Absence or severe reduction in the amount of ergosterol in the fungal membrane and its replacement with other sterols have been described as potential antifungal resistance mechanisms in fungi. AIMS AND METHODS The ergosterol content in a collection of 51 clinical yeast isolates, including susceptible and resistant strains to amphotericin B and azoles, was estimated by a simple chromatographic method (HPLC-UV). RESULTS A high content of ergosterol was detected for several strains of Candida glabrata, Candida tropicalis or Pichia membranifaciens. In contrast, strains of Cryptococcus neoformans and Dipodascus capitatus had the lowest ergosterol concentrations. No significant correlation was observed between antifungal susceptibility patterns and ergosterol content. CONCLUSIONS We conclude from this study that ergosterol content on yeasts may not be associated with specific resistant patterns.