A comparative study on morphological versus molecular identification of dermatophyte isolates

Area of Science:

• Medical Mycology
• Molecular Biology
• Clinical Diagnostics

Background:

• Dermatophytes are fungi causing superficial infections, notoriously difficult to identify due to pleomorphism and slow growth.
• Accurate identification is crucial for effective treatment and epidemiological studies.
• Conventional morphological identification methods often lack precision.

Purpose of the Study:

• To compare morphological and molecular identification methods for clinical dermatophyte isolates.
• To evaluate the accuracy of molecular identification techniques in mycology.

Main Methods:

• DNA extraction from clinical dermatophyte isolates.
• Amplification of the ITS1-5.8S-ITS2 rDNA region using ITS1 and ITS4 primers.
• Restriction Fragment Length Polymorphism (RFLP) analysis with the MvaI enzyme.
• Comparison of RFLP patterns with reference profiles and conventional identification results.

Main Results:

• PCR-RFLP identified Trichophyton rubrum as the most common agent (36.01%), followed by T. interdigitale (27.20%), contradicting initial morphological assessments.
• A significant proportion (80.8%) of isolates identified morphologically as T. interdigitale were reclassified as T. rubrum by PCR-RFLP.
• Morphological methods misidentified several isolates, classifying some as T. interdigitale, Epidermophyton floccosum, Microsporum canis, Trichophyton verrucosum, and T. tonsurans, while molecular methods provided distinct classifications.

Conclusions:

• Molecular methods like PCR-RFLP offer superior accuracy for dermatophyte identification compared to conventional methods.
• A high percentage of misidentification occurred with traditional methods, particularly confusing T. rubrum and T. interdigitale.
• ITS-RFLP or ITS sequencing is highly recommended for accurate dermatophyte identification, especially in epidemiological research.