Could liposomal amphotericin B (L-AMB) lock solutions be useful to inhibit Candida spp. biofilms on silicone biomaterials?

Objectives: Candida infections associated with catheters remain difficult to manage. Antifungal lock strategies could be a therapeutic option when the device is difficult to remove or in combination with systemic treatment to increase efficacy. This study deals with the antibiofilm potential of liposomal amphotericin B (L-AMB) used as a lock solution to inhibit Candida albicans, Candida glabrata and Candida parapsilosis biofilms in vitro. Methods: Biofilms aged 12 h and 5 days were formed on silicone catheters. L-AMB (200 or 1000 mg/L) was added to biofilms and catheters were incubated for 4, 12 or 24 h at 37 degrees C. L-AMB was then removed by washing. The metabolic activity of yeasts was assessed by the XTT method up to 48 h after the end of the locks to evaluate the persistence of the antibiofilm activity. Controls without antifungal were used as references to calculate the inhibition percentages induced by L-AMB lock solutions. Results: L-AMB (200 and 1000 mg/L) inhibited, for up to 48 h, C. albicans and C. glabrata biofilms by >70%, regardless of the lock duration. The activity of L-AMB (200 mg/L) against C. parapsilosis mature biofilms was lower and less sustained, especially for 4 h locks. Conclusions: L-AMB (1000 mg/L) lock solutions strongly inhibited Candida spp. in young and mature biofilms for up to 48 h after the end of the lock. However, overall eradication of the biofilm was not obtained using 1000 mg/L L-AMB as a single lock. These results suggest the usefulness of systemic treatment combined with an L-AMB lock to control Candida spp. biofilms associated with catheters.