Antifungal Susceptibility Testing of Dermatophytes: Screening of Resistant Strains and Investigation of Their Mechanism of Resistance

Dermatophytosis is the most common fungal infection of the skin. The clinical presentations include tinea capitis, tinea corporis, tinea cruris, tinea unguium, and tinea pedis. The pathogens are a group of fungi called dermatophytes, that can degrade human and animal keratin and used it as a nutrition source. Taxonomically, dermatophytes consist of three genera, viz. Trichophyton, Microsporum, and Epidermophyton. The incidence of resistance of dermatophytes to antifungals has been regarded as low. However, the number of patients who responded poorly to conventional treatments are on the rise in recent years. Some patients with tinea corporis responded poorly to the treatment of different antifungal agents. Resistance to single or multiple antifungals was noted through antifungal susceptibility testing in these strains. Recent research showed that resistance of dermatophyte to terbinafine results from the point mutation of the squalene epoxidase gene and resistance to itraconazole results from the efflux pump of the fungal cells. Other mechanisms of resistance are currently under investigation. Dermatophytosis is an important issue in dermatology, not only because of the high patient number but also because of the increase of recalcitrant cases. The aims of this research are to (1) determine the susceptible range of clinical strains to antifungals of different categories, (2) determine the percentage of resistant strains, and (3) investigate the mechanism of the resistant. This study will be the extension of our first-year pilot study. We will determine the susceptible range of wild type and mutant type dermatophyte strains to different antifungals and knowing the molecular mechanisms of resistance belong to any currently known or a new one. The study results will help clinicians to choose proper drugs in treating patients. Furthermore, we will establish a platform for resistance screening and nationwide monitoring. The final goal is to detect resistance timely and control it from spreading. The resistant strains found in this study will be served as an important material for the study of resistance mechanisms and used for new drug development and revaluation.

Project ID:PC10907-1546
External Project ID:MOST109-2314-B182-016