Antifungal Susceptibility Pattern among Candida species: An Evaluation of Disc Diffusion and Micro Broth Dilution Method

Abstract

Objective: Candida species are emerging as a significant pathogen certain species of Candida like Candida krusei are inherently resistant to azoles. In vitro susceptibility testing is essential for guiding therapy. The present study aims to study the antifungal susceptibility pattern of Candida isolates by disc diffusion and micro broth dilution method and to evaluate the degree of agreement between both the techniques. Methods: Candida isolated from specimens like Oropharyngeal swabs, blood, pus and wound swabs were included in the study. Speciation was done as per standard microbiological methods. Antifungal resistance was determined by disc diffusion method for fluconazole, Itraconazole, amphotericin B, nystatin and clotrimazole. Microbroth dilution method was performed for fluconazole, Itraconazole and amphotericin B. The degree of agreement between both the methods for the resistant isolates was analysed by deriving the kappa value. Results: Out of the 156 Candida isolates obtained, Candida albicans was the most common species isolated. By disc diffusion method fluconazole and Itraconazole showed an overall resistance of 34 (21.7%) and 27 (17.3%), respectively. Using micro broth dilution method, Fluconazole and Itraconazole had a resistance percentage of 35 (22.4%) and 29 (18.5%), respectively. There was a good agreement between both the methods in detecting the percentage of resistant isolates for fluconazole and Itraconazole (κ=0.9). Conclusion: It is essential to perform susceptibility testing for all the Candida isolates for providing crucial information about the resistance pattern and help in choosing the appropriate antifungal drug for therapy. Disc diffusion method which is easy to perform can be utilized for day to day practice. J Microbiol Infect Dis 2018; 8(3):97-101