In vitro activities of 8 antifungal agents against geophilic dermatophyte isolates

Background Members of the Nannizzia gypsea complex are globally the most common geophilic dermatophytes which cause infection in animals and human. Although the susceptibility patterns of anthropophilic or zoophilic dermatophyte species to antifungal agents are well documented, the effectiveness of such drugs against geophilic species have rarely been explored. Objectives This study was aimed to evaluate the in vitro antifungal activity of common and new antifungals against a set of environmental and clinical geophilic dermatophyte isolates. Methods 108 soil and clinical geophilic isolates from two genera Nannizzia (N. fulva n = 59; N. gypsea n = 43) and Arthroderma (A. quadrifidum n = 4; A. gertleri n = 1; A. tuberculatum n = 1) were included in the study. The in vitro antifungal susceptibility patterns of eight common and new antifungals against the isolates were determined according to broth microdilution method and by CLSI M38-A3 (3rd edition) protocol. Results MIC values across all isolates from five species ranged as: luliconazole: 0.0002-0.002 mu g/ml, terbinafine: 0.008-0.125 mu g/ml, efinaconazole: 0.008-0.125 mu g/ml, ciclopirox olamine: 0.03-0.5 mu g/ml, itraconazole: 0.125-1 mu g/ml, amorolfine hydrochloride: 0.125-4 mu g/ml, griseofulvin: 0.25-2 mu g/ml and tavaborole: 1-8 mu g/ml, respectively. Conclusion Luliconazole, terbinafine and efinaconazole exhibited the highest in vitro efficacy, regardless of the dermatophyte species. Further surveillance studies are recommended to confirm the implication of such in vitro data for the clinical recovery rate of dermatophytosis with geophilic species following antifungal therapy.