Malassezia furfur causes
**Core Concept**
Malassezia furfur is a lipophilic yeast that resides on the skin surface and is involved in various skin conditions, primarily those related to seborrheic dermatitis and acne. This yeast species thrives in oily environments and feeds on the lipids present on the skin.
**Why the Correct Answer is Right**
Malassezia furfur is implicated in the pathogenesis of seborrheic dermatitis, a chronic inflammatory skin condition characterized by erythema, flaking, and scaling. The yeast species produces lipases that break down sebum into free fatty acids, leading to inflammation and an immune response. The resulting cytokine release triggers a cascade of inflammatory events, contributing to the clinical manifestations of seborrheic dermatitis.
**Why Each Wrong Option is Incorrect**
* **Option A:** While Malassezia furfur is associated with skin conditions, it is not a primary cause of psoriasis. Psoriasis is a chronic autoimmune condition characterized by hyperproliferation of keratinocytes, not directly related to yeast infections.
* **Option B:** Malassezia furfur is not a causative agent of diphtheria, a bacterial infection caused by Corynebacterium diphtheriae. The primary pathogenesis of diphtheria involves the production of diphtheria toxin by the bacteria.
* **Option C:** Malassezia furfur is not a common cause of candidiasis, a fungal infection typically caused by Candida species such as Candida albicans. While both organisms are yeast-like, they belong to different genera and have distinct pathogenic mechanisms.
**Clinical Pearl / High-Yield Fact**
Malassezia furfur is often misidentified as a "normal skin flora," but its lipophilic nature and lipase production contribute to its pathogenic potential in various skin conditions.
**Correct Answer: D. Seborrheic dermatitis.**