Possible role of azole and echinocandin lock solutions in the control of Candida biofilms associated with silicone

Until now, management of candidiasis related to implanted devices has remained problematic. The aim of this study was to investigate antifungal lock strategies against Candida albicans and Candida glabrata biofilms in vitro. Three antifungal agents were used against eight C. albicans and six C. glabrata clinical strains isolated from infected catheters. Caspofungin and micafungin, both echinocandins, as well as the azole posaconazole were tested. An in vitro model of Candida biofilm on 100% silicone catheters was used. Efficacy of the antifungal lock was tested against biofilms aged 12 h and 5 days following exposure to caspofungin (5 mg/L and 25 mg/L), micafungin (5 mg/L and 15 mg/L) and posaconazole (10 mg/L) for 12 h. Persistence of antibiofilm activity was investigated 1-3 days following drug elimination. Antifungal lock was considered effective in the event of a significant decrease (P < 0.001) in the metabolic activity of the biofilm yeast. The results showed that micafungin had significant inhibitory effectiveness against young and mature C. albicans and C. glabrata biofilms. Moreover, this activity appeared to persist for up to 3 days. Caspofungin displayed similar activity against all C. albicans biofilms, but the activity was less persistent for C. glabrata biofilms. Posaconazole was less effective against C. albicans biofilms, but its activity was sustained. Echinocandin lock therapy could significantly enhance the management of candidiasis in patients with indwelling catheters by combating biofilms and enabling device maintenance in situ.