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