Evaluation of in vitro activity of ciclopirox olamine, butenafine HCl and econazole nitrate against dermatophytes, yeasts and bacteria

Background In many instances, a cutaneous fungal infection may exist concomitantly with bacterial involvement. In this study we compared the in vitro activity of three antifungal agents against the dermatophytes, yeasts and bacteria recovered most commonly from cutaneous mycoses and bacterial infections. Methods Using a microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS), we determined the minimum inhibitory concentrations (MICs) of ciclopirox olamine, econazole nitrate and butenafine HCI against a panel of dermatophyte fungi and yeasts (n = 39) and bacterial isolates (n = 45). Results All three antifungals demonstrated comparable activity against the dermatophytes tested, with a MIC range of 0.03-0.25 mug/ml for ciclopirox, < 0.001-0.25 μg/ml for econazole and 0.03-0.25 μg/ml for butenafine. For yeasts, ciclopirox showed activity against all isolates, with an MIC range of 0.001-0.25 μg/ml, whereas econazole had a broader range of 0.125-> 0.5 mug/ml. Butenafine displayed limited activity against the yeast Candida albicans and no activity against Malassezia furfur. For the antibacterial activity studies, ciclopirox demonstrated activity against all isolates tested with a range of 0.06-2 mug/ml, while econazole showed activity against Gram-positive bacteria only, with a MIC range of 0.004-0.25 mug/ml. Butenafine HCI had a limited activity against bacterial isolates tested, showing activity against beta-hemolytic Streptococcus Group A and Corynebacterium only. Neither econazole nitrate nor butenafine HCI demonstrated activity against any of the Gram-negative strains evaluated in this study. Conclusions The data suggest that ciclopirox olamine has the broadest in vitro activity, in comparison to econazole and butenafine HCI, against bacteria, yeasts and bacteria. These findings may have implications in the use of these antimycotics in the treatment of mixed cutaneous infections where bacteria or yeasts are present in addition to dermatophytes.