Genotypic and Phenotypic Identification of Dermatophytes among Clinical Isolates

Abstract

Background: The prevalence of superficial fungal infections varies based
on environmental and hygienic conditions. Dermatophytes, particularly
Trichophyton rubrum and T. mentagrophytes, are keratinophilic fungi
responsible for the majority of these infections. Their ability to produce
proteases and keratinases active at acidic pH facilitates colonization of
human skin. This is a fundamental mechanism observed in Trichophyton
rubrum and Trichophyton mentagrophytes in establishing superficial
infection.
Methods: A total of 200 clinical samples from patients with suspected
dermatophytosis were examined using potassium hydroxide (KOH) mount
and culture techniques. Culture-positive isolates were further identified
through conventional mycology and molecular methods, including PCR and
sequencing using species-specific ITS2 primers for T. rubrum and T.
mentagrophytes. Clinical profiles, treatment history, and recurrence patterns
were also analyzed.
Results: Among 200 KOH-positive samples, 140 yielded culture-positive
results, of which 60 isolates were identified as dermatophytes. Molecular
identification confirmed 20 isolates as T. rubrum and 40 as T.
mentagrophytes. Clinically, 43.34% of cases were naïve infections, 50%
had ongoing antifungal treatment for 1–2 years (recalcitrant cases), and
6.66% were categorized as reinfections due to recurrence of lesions posttherapy. The mean patient age was 30.02 ± 10.95 years, with a male-tofemale ratio of 2:1.
Conclusion: Trichophyton mentagrophytes was more prevalent than T.
rubrum among dermatophyte-positive cases. The high rate of recalcitrant
and recurrent infections highlights the need for accurate species-level
diagnosis using molecular tools to guide effective antifungal management
strategies.