What organism causes tinea versicolor?

Tinea versicolor, also known as pityriasis versicolor, is caused by the organism Malassezia furfur, which is a species of yeast that is part of the normal flora of the skin. This condition manifests as hypopigmented or hyperpigmented macules and patches on the skin, often affecting the trunk, neck, and upper arms.

Malassezia furfur is lipophilic and thrives in areas with high sebaceous gland activity, which is why it is commonly found on the skin. The organism alters the production of melanin in the skin, leading to the characteristic discolored patches. The diagnosis can often be made based on the appearance of the skin lesions and may be confirmed with a microscopic examination of skin scrapings, showing the characteristic 'spaghetti and meatballs' appearance of the hyphae and yeast forms.

The other organisms listed are associated with different infections or conditions. Candida albicans primarily causes thrush and various types of candidiasis, Trichophyton rubrum is a fungus commonly associated with dermatophyte infections like athlete's foot and ringworm, and Aspergillus niger is a mold that may cause respiratory infections or other conditions but is not related to skin pigmentation issues like tinea