Evaluation of Dermatophyte Test Medium and Sabouraud Dextrose Agar for Isolation of Dermatophyte Species

Abstract

Background and Objective: Dermatophyte infections require laboratory diagnosis before treatment is started. Although direct microscopy is routinely performed but culture of dermatophytes is the gold standard. However, it takes about 4 weeks for species identification on primary media. Our aim was to compare dermatophyte test medium (DTM) as a screening medium for the isolation of dermatophytes in comparison with sabouraud dextrose agar (SDA). Methods: It was a comparative study carried out at the Department of Microbiology of Post Graduate Medical Institute, Lahore over a period of nine months. Samples were collected from one hundred patients with clinically suspected dermatophytoses after taking informed written consent. The samples were examined microscopically and then inoculated on two types of culture media, one Sabouraud dextrose agar (SDA) with added chloramphenicol, gentacin and cycloheximide and other dermatophyte test medium (DTM) with added chlortetracycline, gentacin and cyclohexamide. Results: Fungal growth was observed in fifty-six samples on culture. Out of the fifty-six positive on cultures, nineteen were that of dermatophytes. Out of n = 100 patients, ten were positive on SDA while n = 14 dermatophyte species were able to grow on DTM. A significantly higher positivity (P ³ 0.05) for isolating dermatophytes was observed by DTM as compared to SDA. DTM was able to isolate (71%) of the dermatophytes in first 10 days. Isolation rate of dermatophyte species was higher (73.68%) on DTM as compared to SDA which was 52.6%. Conclusion: Authors recommend the use of dermatophyte test medium for the primary isolation and identification of dermatophyte species to be more effective and time saving.