Comparison of Broth Microdilution Method vs Disk Diffusion Method for Antifungal Susceptibility Testing in Dermatophytosis: A Cross-sectional Study

Abstract

Introduction: Dermatophytosis is frequently associated with relapses following the interruption of antifungal therapy. The incidence of fungal infections, including resistant infections, has increased during the last few years, may be due to inadequate use of drugs or increased incidence of immunodeficiency states. Aim: To compare disk diffusion and broth microdilution methods and to determine in vitro activity of antifungal agents which are most commonly used to treat the dermatophytic infection. Materials and Methods: This was a cross-sectional study which was conducted from November 2016 to April 2018 on 50 dermatophytic strains isolated from skin, hair and nail specimen collected from Dermatology Outpatient Department (OPD) of Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly, Uttar Pradesh, India. All samples were cultured on Sabouraud Dextrose Agar (SDA) and Sabouraud’s Cycloheximide, Chloramphenicol Agar (SCCA) medium and incubated at 25°C upto 21 days. Then antifungal susceptibility was done using disk diffusion and broth microdilution method. Result was analysed Statistical software namely Statistical Package for the Social Sciences (SPSS) 20.0 and graph pad were used to analyse the data. Results: Data analysis of drug susceptibility tests involved a standard 2×2 contingency table. The isolates belong to two genera and five species namely Trichophyton menatagrophytes (44%), Trichophyton rubrum (32%), Trichophyton violaceum (18%), Trichophyton verrucosum (4%) and Epidermophyton floccosum (2%). The kappa value for fluconazole, itraconazole, terbinafine and griseofulvin were 0.419, 0.464, 0.444 and 0.451 respectively for disk diffusion and broth microdilution methods. Conclusion: A good agreement was observed between disk diffusion and broth microdilution method.

Keywords

• dermatophytes
• microscopy
• subculture