In vitro effects of micafungin against Candida biofilms on polystyrene and central venous catheter sections

Long-term inserted and surgically implanted catheters can be colonised by Candida spp. Candida biofilms in vitro are often resistant to antifungal agents. The aim of this study was to investigate the in vitro activity of micafungin (MFG) against six Candida spp. biofilms on polystyrene (PS) and central venous catheter (CVC) sections. Safranin staining and differential interference contrast microscopy were used to demonstrate biofilm production. MFG activity was determined by the reduction in metabolic activity (%RMA) by tetrazolium reduction assay on both substrates. In vitro, Candida albicans, Candida parapsilosis, Candida glabrata, Candida tropicalis, Candida dubliniensis and Candida kefyr produced mature biofilms on PS and CVC sections. MFG was active against C. kefyr (0.5 μg/mL) and C. glabrata (<0.5 μg/mL) on PS. However, MFG displayed resistance (>16 μg/mL) against C. albicans,C. dubliniensis,C. tropicalis and C. parapsilosis. On CVC disks, MFG was active against C. glabrata (1 μg/mL) as well as C. parapsilosis and C. albicans (<0.5 μg/mL). MFG was resistant (>16 μg/mL) against C. dubliniensis, C. tropicalis and C. kefyr. MFG was active in vitro against all six Candida spp. on both substrates. However, MFG could not reduce the metabolic activity completely even at the highest concentration.