In vitro susceptability of the biofilm formed by Candida albicans on the urinary foley catheter to selected antifungal azoles

• Main Authors: Atienza, Helena Beatriz Pati, Rippey, Carmen
• Format: text
• Language: English
• Published: Animo Repository 2018
• Subjects: Urinary organs; Antifungal agents
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8593
• Institution: De La Salle University

The increasing rate of Candida infections in medical devices rendered it as one of the most common nosocomial fungal infections. Candida species usually adhere to the surfaces of these medical devices, such as the latex silicone urinary foley catheter, resulting to biofilm formation capable of withstanding environmental stress including exposure to antifungal drugs. The present study primarily determined the in vitro susceptibility of biofilm formed by Candida albicans on latex silicone urinary foley catheter to antifungal drugs such as posaconazole, fluconazole, miconazole, and voriconazole using standard disc diffusion method. Candida albicans strain used in the study was subcultured on Sabouraud dextrose agar plates, and using two-fold dilution method, the density of the standard inoculum was established at 9.6 x 106 CFU/mL. Standard inoculum was introduced to the urinary catheter strips with surface area of 0.16 mm2 (2 mm x 8 mm) in a 96-well plate for biofilm formation. Nonadherent nonbiofilm cells were removed by gently submerging the infected disks in phosphate buffer solution. Adherent cells were allowed to grow for biofilm formation in a new 96-well plate containing 50 mM glucose and were incubated for 24, 48, and 72 hours. For susceptibility profile, each strip was transferred to a test tube containing 10 mL of distilled water and was vortexed vigorously. Subsequently, a sterile cotton swab was dipped in this solution and eventually inoculated in the Mueller-Hinton agar plates for disc diffusion tests of different antifungal drugs. The plates were incubated for 24 hours and the zone of inhibition diameter of each drug was measured. Results showed that there is a decreasing zone of inhibition diameter observed from 24-hour to 72-hour biofilm formation. Candida albicans biofilm exhibited a susceptible profile against the four antifungal azoles, except for the 72-hour biofilm which exhibited resistance to posaconazole. In this study, the nonadherent nonbiofilm C. albicans is different from the C. albicans biofilm in the latex silicone urinary catheter. The fungal biofilm exhibited tolerance while some biofilms are becoming progressively resistant to these antifungal drugs. Information obtained regarding these model biofilms describing the susceptibility profile of C. albicans biofilm formation can further elucidate resistance mechanism with these current antifungal drugs, and eventually lead to the synthesis and development of even more effective novel therapeutic and pharmacologic interventions designed specifically for fungal biofilm-related infections.