**Question:** All are yeast-like fungi except -

A. Candida albicans
B. Malassezia furfur
C. Aspergillus fumigatus
D. Trichosporon species

**Core Concept:** Yeast-like fungi are a group of fungi that share certain morphological and physiological characteristics with yeast. They are important pathogens that can cause infections in humans, including skin, mucous membranes, and deeper tissues.

**Why the Correct Answer is Right:**

C. Aspergillus fumigatus is a filamentous fungus, meaning it has a more complex, branching structure compared to yeast-like fungi. Aspergillus species are known to cause invasive infections, particularly in immunocompromised individuals.

D. Trichosporon species are also filamentous fungi, similar to Aspergillus. They can cause infections, particularly in the skin and nails, but are not as commonly associated with severe systemic infections as Aspergillus.

**Why Each Wrong Option is Incorrect:**

A. Candida albicans is a yeast-like fungus, which makes it different from the correct answer. Candida species are known to cause a variety of infections, particularly in immunocompromised individuals and those with mucocutaneous trauma.

B. Malassezia furfur is another yeast-like fungus known to cause infections on the skin, particularly in individuals with underlying skin conditions and in immunocompromised patients. The main difference between Malassezia and the correct answer lies in the type of infection they cause and their association with immunocompromised individuals.

**Clinical Pearl:** Candida and Malassezia species are often found on the skin and mucous membranes, acting as commensal microorganisms. However, they can cause infections in immunocompromised hosts, suggesting the importance of assessing an individual's immune status when dealing with fungal infections. While understanding the differences between these fungi is crucial for clinical diagnosis and treatment, it is equally important to consider the host's immune status when assessing their susceptibility to fungal infections.