In vitro efficacy of continuous mild heat stress on the antifungal susceptibility of Candida albicans biofilm formation.

Elevation in the temperature induces heat stress to both host cells and the invading pathogen. This study aimed to determine whether continuous mild heat stress (increased temperature without causing significant damage to host cells) can increase susceptibility of biofilm formation of the opportunistic fungal pathogen Candida albicans to low concentrations of three typical antifungal agents. In this way the side effects associated with higher concentrations of the antifungal agents on host cells would be reduced. Fluconazole and micafungin at concentrations ranging from 0.0625 to 2 µg/mL and amphotericin B at concentrations ranging from 0.0625 to 1 µg/mL inhibited less than 20% of cells in biofilm formation. Biofilm formation at 39 or 41°C compared to 37°C resulted in increased susceptibility to the three agents, but especially micafungin. These data suggest that mild heat stress (39°C) would be valuable for increasing the effectiveness of low concentrations of antifungal agents against C. albicans biofilm formation. Thus, the concept of continuous mild heat stress at the site of insertion of medical devices or catheters combined with antifungal agents could be beneficial.