in vitro study of griseofulvin resistant isolates of prevalent dermatophytes in isfahan

Introduction. With report of cases of griseofulvin resistant dermatophytes, the use of new Antifungal drugs such as itraconazole, fluconazole and terbinafine is recommended which are more expensive or somehow rare in Iran. Therefore, study of griseofulvin sensitivity pattern of dermatophytes in Isfahan could lead to a more effective and less expensive treatment for ermatophytoses. Methods. Fifty isolates of the most prevalent dermatophytes in Isfahan were isolated from patients and then the standard homogenized suspensions from them were prepared for future inoculation. The minimum inhibitory concemtration (MIC) of Griseofulvin was determined by modified macrodiution method for each isolate and then results were compared and analysed with standard values of MICs of dermatophytes and the resistant species indentified. Results. All tested isolates (related to four species) had MIC mode of 0.25, 90% had 8 and 50% ranged . between <0.25-1 µ.mg/ml. From all isolates, 10% of them including three T.verrucosum, one M. canis and one T. mentagrophytes had MIC out of standardized range, therfore, they considered as griseofulvin resistant isolates. Discussion. Although MIC valuses of drug in vivo and in vitro are somewhat different but in vitro values could be used as additional parameters in treatment of dermatophytoses, in particular its recalcitrant types or in areas which the resistant species may have high prevalence. In general, the proper application of griseofulvin and knowledge of prevalent species of dermatophytes of region and their drug sensitivity pattern could reduce the use of expensive and rare antifungal drugs for treatment of dermatophytoses in Iran.