Determination of antifungal minimum inhibitory concentration and its clinical correlation among treatment failure cases of dermatophytosis

Introduction: Dermatophytes are most common infectious agents causing superficial mycosis worldwide. A number of topical as well as systemic antifungal drugs are available for treatment of dermatophytosis. Superficial mycosis caused by dermatophytes can be easily treated by topical or oral antifungal drugs, but in the course of time, an increased number of treatment failure cases are appearing. Possible cause for treatment failure could be poor patient compliance, poor drug penetration into affected lesion, and also drug resistance in dermatophytes. The aim of this study is to investigate minimum inhibitory concentration and clinical correlation in treatment failure cases of dermatophytosis. Methods: Skin, hair and nail samples were collected from treatment failure cases of dermatophytosis. A total 75 isolates were tested for MIC against four antifungal drugs in the study. Fluconazole, itraconazole, ketoconazole and terbinafine were the antifungal drugs tested using broth microdilution method. MIC50 and MIC90values were recorded. Results: A total of 75 dermatophytic isolates were tested. Dermatophytic isolates in this study were Trichophyton mentagrophytes (n = 31), T. rubrum (n = 13), T. tonsurans (n = 12), T. verrucosum (n = 9), M. gypseum (n = 5), E. floccosum (n = 4) and T. violaceum (n = 1). MIC90 value for fluconazole and terbinafine was significantly higher. Conclusion: MICof 17.33% isolates for fluconazole and 33.33% isolates for terbinafine were lower than cut-off value, which indicates that not all treatment failure cases are due to drug resistance.