Evaluation of the Multiplex Real-Time PCR DermaGenius® Assay for the Detection of Dermatophytes in Hair Samples from Senegal

Abstract

For the successful treatment of dermatophytoses, especially tinea capitis, there is a need for accurate and rapid diagnostic methods. A lot of recent literature has focused on the detection of dermatophytes directly on sample material such as nails, hair and skin scrapings. Molecular tools offer the ability to rapidly diagnose dermatophytosis within 48 h. This study aimed to compare the results of a commercial real-time PCR (real-time PCR) assay DermaGenius®(DG) 2.0 complete multiplex kit with those of conventional diagnostic methods (direct microscopy and culture). A total of 129 hair samples were collected in Dakar (Senegal) from patients suspected of dermatophytosis. DG was applied for the molecular detection of Candida albicans, Trichophyton rubrum/soudanense, T. interdigitale, T. tonsurans, T. mentagrophytes, T. violaceum, Microsporum canis, M. audouinii, Epidermophyton floccosum, T. benhamiae and T. verrucosum. Dermatophytes species and C. albicans were differentiated by melting curve analysis. The sensitivity and specificity of the PCR assay were 89.3% and 75.3%, respectively. DG PCR was significantly more sensitive than culture (p < 0.001). DG PCR is fast and robust to contamination. In this paper, the main questions discussed were the replacement of culture by a broad-spectrum fungal real-time PCR and the implementation of DG PCR into a routine laboratory in Senegal.

Concept of tinea capitis

“…Dogo et al (2016) showed that the prevalence of Tinea capitis with regards to the age was lower for the age group from 5 to 10 years (42.6%) compared to the age group between 11 to 15 years (50%). Ndiaye et al (2022) reported the prevalence of Tinea capitis in prepubertal males (35.3%) was lower than that of females (56.7%) while the prevalence of Tinea capitis among the pubertal age between 11 to 15 years was lower in females (20%) compared to males (48.4%). Microsporum canis is commonly responsible for tinea capitis cases in South America, Australia, Africa and Western Europe (Table 1) while Trichophyton violaceum causes the majority of this superficial infection in South Asia and Eastern Europe (Gupta and Summerbell, 2000).…”

“…In all forms of Tinea capitis, the characteristic features include inflammation and partial hair loss. There is a correlation between T-lymphocyte activation, inflammatory responses and recovery (Ndiaye et al, 2022). Adesiji et al (2019) reported a case-control study to examine the etiological agents and predispose factors of tinea capitis from school pupils and observed that Tinea capitis is more common in children of age between 4 to 11 years.…”

“…Poor hygiene is another predisposing factor that may support the dissemination of Tinea capitis among prepubertal children. However, older children may not be affected with this factor because of their relatively good hygiene practices when they reach their pubertal ages (Ndiaye et al, 2022). Hairs of different length, no skin lesions and commonly involves eyebrows and eyelashes (Kelly, 2012;Durosaro et al, 2009) Alopecia areata Fine miniature hair growth, exclamation point hairs or total loss of hair, no skin lesions but with discrete patches of hair loss, no inflammation and crusting but with possible nail pitting (Ely et al, 2014;Durosaro et al, 2009) Seborrheic dermatitis Greasy scale with uncommon lymphadenopathy and alopecia, evenly spread across chest, nasolabial folds, postauricular folds, hairline and eyebrows (Kelly, 2012;Ely et al, 2014) Atopic dermatitis Alopecia, annular and lymphadenopathy are less common, family or personal history of atopy (Kelly, 2012;Ely et al, 2014) Psoriasis More than 68% of affected individuals have family history of psoriasis with nail pitting, silver or gray scale (Durosaro et al, 2009;Ely et al, 2014) Bacterial scalp abscess Hair pluck is sore and uncommon alopecia (Kelly, 2012;Ely et al, 2014) 138 2012).…”

“…Real-time PCR is a potentially attractive diagnostic method, the detection and amplification of the pathogen DNA is examined in one step. Ndiaye et al (2022) reported in their studies that the DG PCR assay revealed to be highly specific and sensitive for the identification and detection of dermatophytes directly from clinical specimen. Ndiaye et al (2022) also reported that culture and microscopy were evaluated as the gold standard and PCR assay shows 89.3% and 75.3% of sensitivity and specificity respectively which is agreed with this study (Table 3).…”

Detection of emerging genotypes in Trichophyton mentagrophytes species complex: A proposal for handling biodiversity in dermatophytes

“…For limited sets of the most common species, a commercial non-culture, molecular assay, DermaGenius 2.0 multiplex real-time PCR kit (Pathonostics, Maastricht, The Netherlands) are available. This tool provides rapid detection of superficial fungal infections of nail, hair, and skin samples and readily differentiates species of Trichophyton , Microsporum and Epidermophyton in addition to Candida albicans ( Ndiaye et al, 2022 ). The kit lacks a probe for T. indotineae , a resistant and hypervirulent dermatophytes species ( Singh et al, 2021 ).…”