As growing the number of aging population and immunocompromised patients, there has been an increase in patients with skin fungal infections. Trichophyton rubrum, Trichophyton mentagrophytes and Candida albicans are known as the key pathogen of superficial dermatomycosis. Although itraconazole, terbinafine, amorolfine, and ciclopirox have been used for the treatment of these infections, they have limitation due to the drug side effects and lack of efficacy. In 2014, the Food and Drug Administration approved efinaconazole as a novel antifungals particular in onychomycosis. However, there has not been studied about the efficacy of efinazonazole for specific strains yet.
So, we analyzed the antifungal activities of efinaconazole against T. rubrum, T. mentagrophytes, and C.albicans and compared with the antifungal activities of itraconazole, terbinafine, amorolfine, and ciclopirox in vitro.
63 strains of T. rubrum, 59 strains of T. mentagrophytes and 50 strains of C. albicans were isolated from patient with onychomycosis and tinea pedis. The antifungal activities of efinaconazole, itraconazole, terbinafine, amorolfine and ciclopirox were compared using minimal inhibitory concentration (MIC).
The MIC range of efinaconazole was 0.001-0.125 μg / mL for T. rubrum, 0.0005-0.125 μg / mL for T. mentagrophytes and 0.0002-0.002 μg / mL for C. albicans. It was the lowest MIC among the antifungal agents used in this study.
For most evaluated antifungal agents, a significant number of resistant strains were observed. The MICs of efinaconazole showed relatively small standard deviations. These results suggest that efinaconazole resistant strains did not appear. 
In summary, efinaconazole can be considered as a new alternative antifungal agent that goes beyond the limits of traditional antifungal agents.

Comparison of Antifungal Activities of Efinaconazole and Conventional Antifungal Agents against Dermatophytes and Yeasts