Determination of susceptibility/resistance to antifungal drugs ofTrichophyton mentagrophytesisolates by a macrodilution method

Abstract

Onychomycosis is a common adult human mycosis, and dermatophytes of the Trichophyton genera are the most frequently isolated microorganism. Globally, from 3% to 10% of the human population is attacked by ony cho mycosis, and many cases involve toenails. The aim of this work was to determine the minimal inhibitory concentrations (MICs) of antifungal drugs (fluconazole, ketoconazole, itraconazole, terbinafine, and griseofulvin) often used for the treatment of ungueal dermatophytosis caused by Trichophyton mentagrophytes. The MICs were determined by the broth medium macrodilution method. The results showed that activities of terbinafine and itraconazole were significantly higher (MIC <0.007–0.015 µg·mL–1and MIC = 0.062–1.000 µg·mL–1, respectively). All isolates had reduced susceptibility to fluconazole (MIC = 16 to >64 µg·mL–1). The MICs of ketoconazole and griseofulvin varied among strains, ranging from 0.125 to 2.000 µg·mL–1for ketoconazole and from 0.25 to 2.00 µg·mL–1for griseofulvin. These MICs were higher than those of other studies cited, possibly because of differences in culture medium used in the other studies.Key words: dermatophytes, susceptibility testing, macrodilution, onychomycosis, antifungal drugs.