Isolation and Characterization of Dermatophytes in a Tertiary Care Hospital in Thiruvananthapuram, South India

Abstract

Background and aim: The study was done to identify and characterize the fungal species causing the various clinical types of Dermatophytosis by microscopy, culture and biochemical tests. It also compared the efficacy of the culture media for isolating the dermatophytes and observed the current trend of the etiological fungal species in the locality.Material and methods: The study included 82 patients exhibiting clinical signs of Dermatophytosis. Skin and nail scrapings and nail clippings were examined by direct microscopy; cultures using DTM (Dermatophytes test medium)and SDA (Sabouraud dextrose agar)with cycloheximide were performed; and biochemical tests, such as the urease test and the hair perforation test, were performed.Results: Tinea corporis was the most common type [55 (67.07%)]. Three-quarters of the patients had no co-morbidities, and diabetes was not a significant association. Direct microscopy was positive for fungus in 71 (86.58%) samples. In comparison, only 57 (69.51%) were positive by culture, but one sample was positive by culture, although negative in direct microscopy, indicating the need for culture if skin scraping is negative. Interestingly, Trichophyton mentagrophytes (44, 77.19%) was the most common species and was conforming to the current trend, which makes one wonder if that could be contributory to Dermatophytosis occurring even in those without co-morbidities. Also, DTM was more useful for faster primary isolation of fungus compared to SDA with cycloheximide.Conclusions: The current mycological profile reveals that Trichophyton mentagrophytes are the emerging fungal pathogen, and DTM is a more effective medium than SDA with cycloheximide.

Keywords

• microscopy
• tinea
• trichophyton