A descriptive study of antifungal susceptibility of the dermatophytes isolates by microbroth dilution technique

Objectives: To isolate and identify the dermatophytes from the samples received by the microbiology laboratory of a tertiary care hospital and to determine the antifungal susceptibility of dermatophyte isolates by the microbroth dilution technique. Materials and Methods: Skin scrapings, nail clippings, and hair samples of the patients attending the dermatology outpatient department were received at the microbiology laboratory. Post identification of the isolates, antifungal susceptibility testing by the microbroth dilution method in accordance with the Clinical and Laboratory Standards Institute M38-A2 guidelines was performed for the study. Statistical analysis: Graphical and tabular representation was done using Microsoft Excel. Nominal data among qualitative variables included age and sex of the subject. Frequency and percentage were used to express quantitative data. Comparisons between groups were performed using Chi-square and P < 0.05 was considered statistically significant. Results: This study analyzed 178 clinically diagnosed dermatophytosis cases. Culture positivity was 37.1% (66 isolates). Trichophyton mentagrophytes was the most frequent isolate from skin (57.1%) and nail (66.7%) samples, followed by Trichophyton rubrum . Antifungal susceptibility testing revealed terbinafine as the most effective agent, with the lowest minimum inhibitory concentration (MIC) range (0.015-0.06 mg/mL), MIC50 (0.015 mg/mL), and MIC90 (0.06 mg/mL). Clotrimazole followed with (MIC range: 0.125-1 mg/mL), while fluconazole showed the highest MIC values (2-64 mg/mL), with MIC50 and MIC90 at 2 mg/mL and 64 mg/mL, respectively. Conclusions: Antifungal susceptibility testing revealed terbinafine as the most sensitive drug, followed by clotrimazole, while fluconazole showed the highest MIC values, indicating lower sensitivity.