In vitro Resistance Pattern of Selected Antifungal Azoles against Candida albicans Biofilms on Silicone Nasogastric Tube

摘要

Prolonged use of implanted medical devices has been linked with device-associated infections. Sinceenteral tube feeding is increasing worldwide, the present study described the morphology of Candidaalbicans biofilms on the surface of silicone nasogastric tube (NGT) using fluorescence microscopy. Withthe emergence of multidrug-resistant fungal infections, the present study assessed the susceptibilityprofile of the biofilms to antifungal azoles namely fluconazole, miconazole, voriconazole, andposaconazole using the standard disc diffusion method. Microscopic studies of C. albicans biofilmsrevealed a complex heterogeneous structure with yeast cells and hyphal elements entrenched within apolysaccharide matrix. Planktonic C. albicans cells remained susceptible with posaconazole, fluconazole,miconazole, and voriconazole. However, the fungal biofilms exhibited resistance with miconazole. Therewas a significant reduction in the zone of inhibition on the 24-h, 48-h, and 72-h biofilm formation withposaconazole, voriconazole, and fluconazole, respectively. Kinetic investigation on C. albicans biofilmwith posaconazole revealed a zero-order kinetic profile (R2=0.9774) whereas with voriconazole exhibiteda first-order kinetic profile (R2=0.9974). These findings can possibly provide information regarding theresistance of fungal biofilms with antifungal azoles. Demonstration of common biofilm features willextend the findings of this study beyond fungi to polymicrobial infections, as new information andinsights will influence several disciplines ranging from environmental microbiology to pharmaceuticaldrug design intended for biofilm-associated infections.