Identification of the causative dermatophyte of tinea capitis in children attending Mbarara Regional Referral Hospital in Uganda by PCR-ELISA and comparison with conventional mycological diagnostic methods

Abstract

Tinea capitis is a dermatophyte infection common among prepubertal children in sub-Saharan Africa and mainly caused by Trichophyton and Microsporum species. Accurate identification is challenging as conventional methods like culture and microscopy are slow and mostly based on morphological characteristics, which make them less sensitive and specific. Modern molecular methods, like polymerase chain reaction (PCR) assays, are gaining acceptance and are quick as well as accurate. The aim of this study was to investigate the clinical patterns of tinea capitis and to accurately identify the most common causative dermatophytes affecting the scalps of children aged 1 to 16 years attending the Skin Clinic at Mbarara University of Science and Technology (MUST), Mbarara, Uganda, East Africa, using both conventional mycological methods and PCR-ELISA for detection of dermatophyte DNA. One hundred fifteen clinical samples from children from Western Uganda attending the MUST Skin Clinic with a clinical diagnosis of tinea capitis were analyzed. T. violaceum was identified as the most common causative agent, followed by M. audouinii, T. soudanense, and T. rubrum. The early identification of the causative agent of tinea capitis is a prerequisite for the effective management of the disease, the identification of probable source and the prevention of spreading. Children with tinea capitis in Western Uganda should be treated by systemic therapy rather than topical preparations to ensure high cure rates as the most common causative dermatophytes T. violaceum exhibits an endothrix rather than ectothrix invasion of the hair follicle.

Tinea capitis in adults: A 18‐year retrospective, single‐centre study in Korea

“…Swabs were directly inoculated on SDA agar, while hair and skin scraping were examined by direct microscopy and then cultured on SDA agar. Causative fungal species were identified based on the macro‐ and microscopic morphological characteristics of colonies on SDA and, in selected cases, by PCR using primers targeting the internal transcribed spacer (ITS) regions, ITS1 and ITS4, as has been previously described …”

“…Causative fungal species were identified based on the macro-and microscopic morphological characteristics of colonies on SDA and, in selected cases, by PCR using primers targeting the internal transcribed spacer (ITS) regions, ITS1 and ITS4, as has been previously described. 21,22 For each patient, we collected relevant clinical information including age, sex, duration of illness until confirmation of diagnosis, presumptive initial diagnosis, associated underlying systemic diseases or medication, history of animal contact, clinical patterns, accompanying hair loss, involvement of other site in dermatomycoses, treatment response and incidence of recurrence by reviewing patients' electronic or written chart. Clinical pattern was classified as seborrhoeic dermatitis-like diffuse scaling, pustular, grey patch, kerion celsi or black dot type.…”

S1 guidelines: Tinea capitis

“…Both in-house tests and commercially available test systems (kits) may be used for this purpose [50][51][52]. In the aforementioned cases, the disease course correlated with the molecular findings [53,54]. Thus, molecular techniques are significantly more rapid (24-48 hours versus 2-6 weeks for culture-based methods) and sensitive than KOH preparation and culture [43].…”

“…In two other patients, the dermatophyte was detectable by PCR-based methods for several weeks, whereas cultures remained negative. In the aforementioned cases, the disease course correlated with the molecular findings [53,54]. Further comparative studies should be conducted in order to determine whether -apart from enabling more rapid pathogen identification -PCR-based methods are also suitable for treatment monitoring in patients with TC.…”

Non-culture based assays for the detection of fungal pathogens

“…In addition, new data of tinea capitis in Sub-Saharan Africa highlighted the importance of early detection of causative agents. The use of the PCR-ELISA and rapid determination of antropophylic species (T. violaceum, M. audouinii, T. soudanense, T. rubrum) allow the effective and appropriate therapy, monitoring of possible source of infection and implementation of preventive measures with the goal of preventing the spread of causative agents and infection [40].…”