Molecular epidemiology of dermatophytosis in Tehran, Iran, a clinical and microbial survey

Abstract

In the framework of a survey on dermatophytoses, 14,619 clinical specimens taken from outpatients with symptoms suggestive of tinea and referred to a Medical Mycology laboratory in Tehran, Iran, were analyzed by direct microscopy and culture. In total, 777 dermatophyte strains recovered in culture were randomly identified by a formerly established RFLP analysis method based on the rDNA ITS regions. For confirmation of species identification, 160 isolates representing the likely entire species spectrum were subjected to ITS-sequencing. Infection was confirmed in 5,175 collected samples (35.4%) by direct microscopy and/or culture. Tinea pedis was the most prevalent type of infection (43.4%), followed by tinea unguium (21.3%), tinea cruris (20.7%), tinea corporis (9.4%), tinea manuum (4.2%), tinea capitis (0.8%) and tinea faciei (0.2%). Trichophyton interdigitale was the most common isolate (40.5%) followed by T. rubrum (34.75%), Epidermophyton floccosum (15.6%), Microsporum canis (3.9%), T. tonsurans (3.5 %) and M. gypseum (0.5%). Other species included M. ferrugineum, T. erinacei, T. violaceum, T. schoenleinii, and a very rare species T. eriotrephon (each one 0.25%). The two strains of T. eriotrephon isolated from tinea manuum and tinea faciei are the second and third reported cases worldwide. Application of DNA-based methods is an important aid in monitoring trends in dermatophytosis in the community.

Molecular Characterization and In Vitro Antifungal Susceptibility of 316 Clinical Isolates of Dermatophytes in Iran

“…In the present study, T. interdigitale was the predominant pathogen in south of Iran, which corroborates recent findings reported from Iran investigating molecular epidemiology of dermatophytosis in Tehran [18] and north of Iran [17]. Interestingly, in our study, we found a significant increase in the frequency of A. benhamiae (5.38 %) significantly in a higher rate than previous studies in Iran [14,[17][18][19]24], reporting A. benhamiae as a rare dermatophyte.…”

“…Our results confirm those of previous studies in Iran [13,24] and other regions of the world [32,33]. However, our finding is in contrast to others who reported tinea pedis [17,18], tinea capitis [15,32], and tinea cruris [19,20] as the predominant clinical observations in north and center of Iran.…”

“…Interestingly, in our study, we found a significant increase in the frequency of A. benhamiae (5.38 %) significantly in a higher rate than previous studies in Iran [14,[17][18][19]24], reporting A. benhamiae as a rare dermatophyte. Of note, A. benhamiae is a zoophilic dermatophyte species belonging to the T. mentagrophytes complex, which causes highly inflammatory tinea corporis and tinea capitis in humans.…”

“…Despite the variability of fungal species by geographic regions in 1990s, zoophilic fungi such as T. verrucosum overwhelmed the anthropophilic across some regions of the country, including certain endemic areas [14][15][16]. However, today anthropophilic T. mentagrophytes (T. interdigitale), Epidermophyton floccosum, and T. rubrum are the main pathogens in Iran [17][18][19][20][21][22][23][24][25][26][27].…”

Equine Dermatophytosis due to Trichophyton bullosum, a Poorly Known Zoophilic Dermatophyte Masquerading as T. verrucosum

“…2). Trichophyton eriotrephon is known from three cases of human infection [26] that were probably transmitted from animal, based on the clinical picture and phylogenetic position of the species (Fig. 2).…”