Media With pH Indicators for the Isolation of Dermatophytes

Abstract

A comparison was made of four agar media, Sabouraud's glucose agar, mycosel (M), ink blue agar (IB), and dermatophyte test medium (DTM) for the isolation and identification of fungi from 100 dermatological clinical specimens. Except for yeasts, Sabouraud's glucose medium was the least desirable as an isolation medium since it supported the growth of significantly fewer dermatophytes and more contaminants (both fungal and bacterial) than the other three media (M, IB, or DTM). These three media were approximately the same in supporting fewer yeasts (pathogenic and nonpathogenic) and mycelial fungal contaminants than the Sabouraud's. The dermatophyte test medium was superior to the three others in suppressing bacteria. All dermatophytes isolated on the IB and DTM media turned the pH indicators alkaline, and so did certain fungal contaminants. The latter, however, could be distinguished from dermatophytes by their colony characteristics.