Microbiology Testing FAQs — Methods & Media | HiMedia USA

What is Dermatophyte Test Medium used for?

DTM is selective medium for isolation of dermatophytes (Trichophyton, Microsporum, Epidermophyton) from skin, hair, nail specimens. Contains: (1) Cycloheximide and gentamicin - inhibit saprophytic fungi and bacteria, (2) Phenol red pH indicator. Dermatophytes produce alkaline metabolites → medium turns red (yellow to red color change). Saprophytes may grow but don't produce color change or change late. Procedure: Inoculate specimen, incubate at 25-30°C, observe daily. Red color in 3-7 days = presumptive dermatophyte. Confirm with microscopy and subculture. Used in physician offices, clinics for rapid screening.