Modified Sabouraud dextrose agar for isolation and identification of dermatophytes

Abstract

The most common causative agents of dermatomycoses are fungi belonging to genders Trichophyton, Microsporum and Epidermophyton. Media mainly used for isolation of dermatophytes are mycobiotic agar, dermatophyte test medium Sabouraud agar (original formula or modification by Emmons) with or without antibiotics and cycloheximide. Peptones are the most important components of the media, which enable adequate reproductivity in identification of dermatophytes. Standard medium for isolation of dermatophytes is not produced in our country. The aim of the study was to create an optimal easily accessible and economic medium which enables isolation and identification of dermatophytes according to criteria for morphological diagnosis provided by identification guides. We examined 57 strains of Trichophyton, 24 of Microsporum and 5 of Epidermophyton floccosum (E. floccosum). Each strain was seeded on Sabouraud dextrose agar (Torlak Serbia and Montenegro), Sabouraud maltose agar (Torlak), two experimental modified Sabouraud dextrose agar media marked as SA-2 and SA-3 (Torlak) Sabouraud-Chloramp- henicole agar (Biomerieux, France) Sabouraud-Chloramphenicole agar (Himedia, India), Glucose-peptone agar (Himedia, India) and Sabouraud Emmons dextrose Agar with Chloramphenicole and Cycloheximide (Biolife, Italy). Colony morphology of Trichophyton mentagrophytes (T. mentagrophytes) was uni- form on all the media, while morphology of Trichophyton rubrum (T. rubrum) and Microsporum canis (M. canis) depended more on the media type. Colonies of E. floccosum were typical and uniform on all the media, as were the control species of Trichophyton schoenleinii (T. schoenleinii) and Trichophyton soudanense (T. soudanense). Experimental modified Sabouraud dextrose agar (Torlak) marked as SA-3 demonstrated the best results in identification of dermatophytes in this study.