Antifungal drug sensitivity testing in clinical specimens from dermatophyte infection using E-strip disk diffusion technique

Abstract

ABSTRACT Context: The wide range of antifungal agents available poses a difficulty in choosing an effective medication to avoid drug resistance. There is a need for a standard antifungal susceptibility testing method that would guide a practicing dermatologist to prescribe antifungal agents effectively. Aims: The aim of the study was to determine the prevalence of each species of dermatophytic infections and to determine the resistance pattern to common antifungal agents. Settings and Design: A cross-sectional interventional study was conducted at a tertiary health care center. Subjects and Methods: Two hundred consecutive patients diagnosed with dermatophytic infections were examined, and scrapings were sent for 10% potassium hydroxide (KOH) mount examination and culture. Further, antifungal drug susceptibility pattern was tested using the E-strip to determine the minimum inhibitory concentration (MIC) for fluconazole (FCZ), itraconazole (ITZ), clotrimazole, ketoconazole (KTZ), and voriconazole. Statistical Analysis Used: Collected data were analyzed by frequency, percentage, standard deviation, mean and Chi-square test, and Fisher’s exact test. Results: One hundred and thirty-four samples were found to be KOH mount positive, and 81 samples yielded growth on culture. Trichophyton mentagrophytes was the most commonly isolated species in 32 (39.5%) specimens followed by Trichophyton rubrum in 29 (35.8%) samples. T. mentagrophytes showed the least MIC for KTZ, ITZ, and voriconazole (0.032–1.5 mg/L). T. rubrum was seen to have a MIC in the range of 0.04–2 for ITZ, 0.06–1.5 for voriconazole, and 0.13–0.75 for KTZ and highest for FCZ (0.5–32 mg/L), respectively. Conclusions: There is currently no reference method available to test drug sensitivity, and E-test is a simple technique which can be employed for antifungal drug sensitivity testing with less workforce, quick results, and easy interpretation aiding effective treatment of dermatophytic skin infections.