Most common cause of otomycosis ?
**Core Concept**
Otomycosis is a fungal infection of the external auditory canal, typically caused by dermatophytes, yeasts, or molds. It is more common in individuals with compromised immune systems, diabetes, or those who use ear drops excessively.
**Why the Correct Answer is Right**
The most common cause of otomycosis is Aspergillus species, particularly Aspergillus niger. This fungus thrives in warm, humid environments and can penetrate the skin of the external auditory canal. The pathogenesis involves the germination of fungal spores on the surface of the canal, followed by invasion of the skin and subsequent infection. Aspergillus species can produce melanin, which helps to protect the fungus from the host's immune system.
**Why Each Wrong Option is Incorrect**
**Option A:** Aspergillus species are more common than Candida species in otomycosis. While Candida can cause otomycosis, it is less common than Aspergillus.
**Option B:** Dermatophytes are a type of fungus that can cause skin infections, but they are not the most common cause of otomycosis.
**Option C:** Molds, such as Aspergillus, are more common than yeasts, such as Candida, in otomycosis.
**Clinical Pearl / High-Yield Fact**
Otomycosis is often treated with topical antifungal agents, such as clotrimazole or ketoconazole, and may require removal of the infected ear canal skin. It is essential to identify and treat the underlying cause of otomycosis, as recurrence is common if the underlying condition is not addressed.
**Correct Answer: A. Aspergillus species.**