In vitro efficacies of caspofungin or micafungin catheter lock solutions on Candida albicans biofilm growth

Objectives: Caspofungin and micafungin belong to the echinocandins; the mechanism of action of echinocandins is based on the inhibition of (1,3)-beta-D-glucan synthase. The aim of this study was to investigate in vitro the optimal antifungal lock treatment details against a Candida albicans biofilm. Methods: An in vitro model of a C. albicans (ATCC 3153 or ATCC 66396) biofilm associated with 100% silicone catheters was used. The effectiveness of the antifungal treatment was assayed against biofilms aged 12 h or 5 days, after exposure to caspofungin (2 mg/L) or micafungin (5 mg/L) for 12 h. The durability of the reduction in the biofilm metabolic activity was investigated (1-3 days after echinocandin treatment). The efficacy of caspofungin and micafungin was determined by evaluating a significant decrease (P < 0.0001) in the metabolic activity of biofilm yeasts. Results: The results showed that the tested antifungal agents used as lock solution significantly (P < 0.0001) reduced the metabolic activity of C. albicans, whatever the biofilm maturation stage (12 h or 5 days old biofilms). The reduction in the metabolic activity of biofilm yeasts was maintained, even after 48 h. Conclusions: These data suggest that caspofungin (2 mg/L) and micafungin (5 mg/L) could represent good candidates for the reduction or control of fungal biofilms associated with silicone medical devices, as part of an antifungal lock. They were able to induce a significant and persistent reduction in the yeast metabolic activity of intermediate and mature biofilms, 12 h and 5 days old, respectively, when used as catheter lock solutions.