Dermatophyte antigen kit: A useful diagnostic tool for onychomycosis

Area of Science:

• Medical Mycology
• Dermatology
• In Vitro Diagnostics

Background:

• Tinea unguium diagnosis can be challenging due to sparse or atypical fungal elements.
• Traditional potassium hydroxide (KOH) microscopy may yield false-negative results.
• A novel dermatophyte antigen kit (DQT) has been developed for in vitro diagnosis.

Purpose of the Study:

• To evaluate the diagnostic accuracy of the DQT for tinea unguium.
• To compare DQT performance against KOH microscopy and fungal culture.
• To assess the utility of DQT in cases with negative KOH results.

Main Methods:

• Seventy-five patients with KOH-negative nail conditions were tested.
• Dermatophyte antigen kit (DQT) results were analyzed.
• ZoomBlue™ staining at 400× magnification was used for fungal element confirmation.
• Fungal cultures were performed for comparison.

Main Results:

• DQT detected 27 cases of tinea unguium and 2 of non-dermatophyte onychomycosis.
• Fungal cultures confirmed 14 cases, including Trichophyton rubrum.
• DQT-negative cases included cured onychomycosis and mimics like onychauxis and traumatic onycholysis.

Conclusions:

• The DQT is beneficial for diagnosing onychomycosis, particularly when direct microscopy with KOH is inconclusive.
• The kit can identify fungal elements that are sparse, atrophic, or fragmented and invisible under standard microscopy.
• DQT offers improved diagnostic capability for challenging onychomycosis cases.