A 60-year-old man presents with thickened, subungual hyperkeratotic, and dystrophic toenails. A potassium hydroxide mount reveals septate hyphae. Which organism is the most common cause of this condition?
- A Candida albicans
- B Epidermophyton floccosum
- C Trichophyton rubrum ✓
- D Microsporum canis
Correct answer: C. Trichophyton rubrum
Explanation
Onychomycosis is most commonly caused by dermatophytes, with Trichophyton rubrum being the predominant organism globally. Candida albicans is more common in chronic mucocutaneous candidiasis or fingernail involvement in immunocompromised patients. Epidermophyton floccosum and Microsporum canis rarely cause onychomycosis, typically causing tinea corporis or tinea capitis respectively.
Reference: Rook's Textbook of Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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