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Shifting etiological agents of dermatophytosis: a molecular epidemiological study from Iran

Summary

Researchers in Iran studied fungal infections of the scalp and nails using modern DNA testing methods. They found that the main fungus causing scalp infections (T. tonsurans) remains the most common, but a new species (T. indotineae) is increasingly causing nail infections and is resistant to common antifungal medicines. The study shows that traditional identification methods often misidentify these fungi, highlighting the importance of molecular testing for accurate diagnosis and treatment.

Background

Dermatophytosis affects 20-25% of people globally, with tinea unguium (TU) and tinea capitis (TC) being most prevalent. Recent molecular studies have revealed shifting patterns in causative agents, particularly the emergence of Trichophyton indotineae with antifungal resistance.

Objective

This study investigated the molecular epidemiology and species distribution of dermatophytes causing tinea unguium and tinea capitis in Tehran, Iran using ITS region sequencing of ribosomal DNA.

Results

Among 342 suspected patients, 59 (17.2%) were positive by direct examination and 43 (12.5%) confirmed by PCR-sequencing. T. tonsurans was predominant in TC (88% of confirmed cases), while T. indotineae emerged as a significant TU agent (28% of confirmed TU cases). Substantial agreement (κ=0.73) was found between conventional and molecular methods, with 81.8% misidentification of T. mentagrophytes complex.

Conclusion

T. tonsurans remains the predominant TC cause while T. indotineae emerged as a significant TU pathogen. Molecular methods should be used for suspected T. mentagrophytes complex strains but may not be necessary for T. tonsurans and M. canis identifications.
  • Published in:Iran Journal of Microbiology,
  • Study Type:Molecular Epidemiological Study,
  • Source: PMID: 41234643, DOI: 10.18502/ijm.v17i5.19895
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