MHB: a new medium for isolation and identification of dermatophytes

Background Dermatophytes are the most common fungi causing superficial dermatophytosis in Egypt. The isolation of dermatophytes depends mainly on the suitable medium used. Recently, trials were conducted to propagate culture media not only to isolate dermatophytes but also to identify them. Objective The aim of this study was to evaluate the sensitivity of a new medium composed of milk, honey, and bromothymol blue (MHB) in isolation and identification of dermatophyte species. Materials and methods The new medium MHB was used to isolate and identify dermatophytes from 250 samples collected from patients suffering from dermatophytosis. Moreover, the medium was tested for seven reference species of dermatophytes. The identification of dermatophytes on the MHB medium depended on changes in the color of the medium from straw yellow to green and then to blue, hydrolysis of casein, and rate of dermatophyte growth. The medium was compared with other different media used for isolation and identification of dermatophytes. Results The sensitivity of MHB, dermatophyte test medium, bromocresol purple milk solids dextrose agar medium, and Dermasel in isolating dermatophytes was 94.8, 94.8, 93.6, and 92.4%, respectively, and the sensitivity in identification of the species was 100, 71.7, 88.7, and 84.3%, respectively. Conclusion The MHB medium has superior sensitivity for isolation and identification of dermatophyte species. The medium has the advantage that it can be prepared without cycloheximide. It yields good and rapid growth for most dermatophytes and facilitates their identification from the primary culture.