Phenotypic methods versus PCR-RFLP for the identification of dermatophyte species isolated from patients with dermatophytosis in Egypt

Abstract

Background: Dermatophytes are major causative agents of cutaneous fungal infections worldwide. Identification of dermatophyte species is based on macroscopic and microscopic morphology on different culture media. Molecular methods such as PCR-RFLP are rapid, reliable and precise identification methods. This local study aimed to identify the spectrum of dermatophyte species among the studied patients population using different phenotypic and genotypic methods. Materials and methods: Hair, skin and nail specimens were collected from 135 patients with clinically suspected cases of dermatophytosis. All specimens were subjected to microscopic examination using KOH and culture on SDA and dermasel agar. Phenotypic identification was done by colony and microscopic morphology, and subculture on malt, PDA, lactrimel and urea agar plates. Molecular identification was done by PCR-RFLP using MvaI. Results: Out of 135 patients included in the study, 78 (57.8%) were positive by culture for dermatophytes. Five different species were identified, the most commonly isolated species was M. canis (51.3%) followed by T. violaceum (42.3%). PCR-RFLP correctly identified the isolated dermatophyte species, producing unique restriction patterns. Conclusion: Dermatophytosis is common in Egypt where humid hot climate and animal contact play important role in the spread of these fungi. The use of PCR-RFLP directly on clinical specimens rather than its use in the identification of dermatophytes from culture media is recommended.

Dermatophytosis and its risk factors among children visiting dermatology clinic in Hawassa Sidama, Ethiopia

“…In the present study, Tinea capitis was the main clinical manifestation agreeing with a study on African children 17 . A study in Egypt reported Tinea capitis (85.2%) followed by Tinea corporis (8.1%) and Tinea unguium (6.7%) in order were the most frequent cases 18 . This is concordant with our study.…”

Molecular diagnosis of dermatophyte isolates from canine and feline dermatophytosis in Northeast Iran

“…However, phenotypic methods are time-consuming, requires experienced personnel due to identification overlap between species (Arabatzis et al, 2007;De Baere et al, 2010;Gohar et al, 2019), particularly in species with a degenerate appearance such as M. ferrugineum, because colonies may be similar to atypical (dysgonic) variants of M.…”

“…Precise species‐level identification of dermatophytes is mandatory to know the source of infection, whether zoophilic, anthropophilic or geophilic, and to apply proper treatment and control measures (Gohar et al., 2019 ). Conventionally, the identification of dermatophytes including Microsporum spp., especially M. canis , usually depends on phenotypical features, such as direct microscopy and in‐vitro culture.…”

“…However, phenotypic methods are time‐consuming, requires experienced personnel due to identification overlap between species (Arabatzis et al., 2007 ; De Baere et al., 2010 ; Gohar et al., 2019 ), particularly in species with a degenerate appearance such as M. ferrugineum , because colonies may be similar to atypical (dysgonic) variants of M. canis (Gräser et al., 2008 ). In addition, the phenotypical features of dermatophytes may predominantly show variations, which often complicate the diagnosis; these alternations may be affected by numerous factors such as temperature, media, host and user therapy.…”