In-vitro susceptibility of dermatophytes to griseofulvin and ketoconazole and bioassay of ketoconazole

ABSTRACT

Antibiogram together with minimum inhibitory concentration [MIC] of griseofulvin and ketoconazole were determined against 24 dermatophyte strains that were isolated from different ring worm lesions by using the agar dilution methods. These dermatophytes included 7 strains of Trichophyton violaceum, 6 strains of Microsporon canis, 5 strains of Trichophyton rubrum, 3 strains of Trichophyton mentagrophytes, 2 strains of Trichophyton schoenlinii and one strain of Epidermophyton floccosum. All tested dermatophytes were generally susceptible to ketoconazole and to griseofulvin in varying concentrations except one strain of Trichophyton mentagrophytes which was resistant to all concentration of griseofulvin. The [MIC] of griseofulvin Indicated a high susceptibility [0.78 micro gram/ml] of Microsporum canis and a low susceptibility [12.5 micro gram/ml] of Epidermophyton floccosum, The [MIC] of ketoconazole Indicated a high susceptibility of Trichophyton rubrum and Trichophyton violaceum [2 micro gram/ml and 4 micro gram/ml for each respectively] and low susceptibility [16 micro gram/ml] to Epidermpophyton floccosum. Bioassay of ketoconazole on the tested serum samples, indicated that its level had ranged between 0.7 and 4 micro gram/ml and proved that the drug was not accumulated