5 research outputs found
In vitro resistance pattern of selected antifungal azoles against Candida albicans biofilms on silicone nasogastric tube
Prolonged use of implanted medical devices has been linked with device-associated infections. Since enteral tube feeding is increasing worldwide, the present study described the morphology of Candida albicans biofilms on the surface of silicone nasogastric tube (NGT) using fluorescence microscopy. With the emergence of multidrug-resistant fungal infections, the present study assessed the susceptibility profile of the biofilms to antifungal azoles namely fluconazole, miconazole, voriconazole, and posaconazole using the standard disc diffusion method. Microscopic studies of C. albicans biofilms revealed a complex heterogeneous structure with yeast cells and hyphal elements entrenched within a polysaccharide matrix. Planktonic C. albicans cells remained susceptible with posaconazole, fluconazole, miconazole, and voriconazole. However, the fungal biofilms exhibited resistance with miconazole. There was a significant reduction in the zone of inhibition on the 24-h, 48-h, and 72-h biofilm formation with posaconazole, voriconazole, and fluconazole, respectively. Kinetic investigation on C. albicans biofilm with posaconazole revealed a zero-order kinetic profile (R2=0.9774) whereas with voriconazole exhibited a first-order kinetic profile (R2=0.9974). These findings can possibly provide information regarding the resistance of fungal biofilms with antifungal azoles. Demonstration of common biofilm features will extend the findings of this study beyond fungi to polymicrobial infections, as new information and insights will influence several disciplines ranging from environmental microbiology to pharmaceutical drug design intended for biofilm-associated infections. © The Author(s) 2019
Susceptibility profile of Candida albicans biofilms on polyvinyl chloride endotracheal tube to antifungal azoles
One of the most prevalent causative organisms in human fungal infections is Candida albicans. The extensive utility of medical devices such as endotracheal tube has resulted in the increased cases of fungal infections. The present study visualized Candida albicans biofilm on polyvinyl chloride endotracheal tube and described the susceptibility profile of the biofilm to antifungal azoles. Biofilm was examined using light and fluorescence microscopy. The susceptibility profile of planktonic and sessile cells with posaconazole, miconazole, voriconazole, and fluconazole was assessed employing the standard disc diffusion method. Planktonic C. albicans was susceptible to the identified antifungal azoles, whereas the sessile cells had varying susceptibility profiles. The biofilms remained susceptible to voriconazole and fluconazole, susceptible-dose dependent to posaconazole, and resistant to miconazole. Findings of the present study can provide relevant information on the resistance mechanism of fungal biofilms with azoles and in the design of new pharmacologic interventions intended as treatment of mycoses. © The Author(s) 2020
Polymeric compositions of medical devices account for the variations in Candida albicans biofilm structural morphology
The increase in the number of fungal infections has been associated with the prevalent use of medical devices. This study assessed the morphological structure of Candida albicans biofilms on the surfaces of medical devices using scanning electron microscopy and characterized the polymeric compositions of these medical devices using infrared spectroscopic study. Biofilms on the surfaces of these medical devices exhibited variations in morphological topographies ranging from the presence of ellipsoid and spherical yeast cells joining end to end, to the growth of pseudohyphae and hyphae formation with chains of cylindrical cells, and the formation of several microcolonies entrenched in a polymeric matrix. The differences in the spectroscopic profiles of the medical devices accounted for the variations in the structural morphology of these biofilms. Spectral studies on polyvinyl chloride endotracheal tube revealed sp3-CH stretching frequencies at 2959, 2926, and 2858 cm-1 with CCl stretching frequencies at 636 cm-1 and 693 cm-1. Silicone polymer containing medical devices had SiOSi and SiC stretching frequencies identified at 1096 cm-1 and 804 cm-1 for the silicone urinary catheter, while the stretching frequencies were identified at 1005 cm-1 and 862 cm-1 for the silicone nasogastric tube, respectively. Given the information on the variations in the morphological appearance of the biofilms on medical device surfaces, these differences on the polymeric compositions of the medical devices can provide explanations on the adhesion potential, biofilm formation, structural morphology, and subsequent susceptibility pattern of the sessile organism to antifungal drugs. © 2020 Beijing Academy of Agriculture and Forestry Sciences, Institute of Plant and Environment Protection