Survival of Dermatophytes in Skin Scales after 10 Years Storage

Survival of dermatophytesinskin scales and nail scraps sampled from human lesions could have ecological and epidemiologicalimportance.The aim of this study was to store humanskin scale and nail lesions infected with dermatophyteagents,at -20°C for a long timeand to investigate the re-isolation rate of dermatophytes species from such samples after storage.
After referral to Medical Mycology Laboratory of Tehran University of Medical Science, the patients were subjected to sampling. Confirmation of dermatophytepositive result in direct smears was done with Potassium hydroxide, then culturing on Sabouraud dextrose agar media was performed, and species were identifiedusing standard procedures, and remaining samples were stored at -20°C. After 10 years, samples were re-examined for the presence and re-isolation of intended fungi according to the standard procedures.
From a total of 5 species enrolled in this study, Epidermophyton floccosum, Trichophyton mentagrophytes, andTricholosporumviolaceum survived, andTrichophyton rubrum andTrichophytonverrucosumlost their viability at -20°C after 10 years. There was a significant difference between the re-isolation rate and the type of dermatophytes (p Some dermatophytes species including E. floccosum are able to maintain their ability to survive for a long time in human scale samples in certain time and temperature conditions (10 years at -20 °C) and to grow in appropriate conditions. These findings should be considered in ecological and epidemiological studies.