Microbiology Practice Exam

Which type of fungi are known for their dimorphic characteristics?

1. Yeast-like fungi only

2. Filamentous fungi only

3. Yeast-like and filamentous fungi

4. None of the above

The correct answer is: Yeast-like and filamentous fungi

Dimorphic fungi are unique in their ability to exist in two distinct forms depending on environmental conditions. Typically, they can be found in a yeast form at body temperature (approximately 37°C) and in a filamentous (mold) form at lower temperatures (around 25°C). This duality allows them to adapt to varying environments, which is particularly important in the context of infection, as they can transition between forms to evade the host's immune response. This capability is seen in various significant pathogenic fungi, such as Histoplasma capsulatum, Coccidioides immitis, and Blastomyces dermatitidis. These examples highlight the biological significance of the dimorphic nature of these fungi in their lifecycle and pathogenicity. Thus, the correct answer reflects the understanding that both yeast-like and filamentous forms can be present in certain species of fungi.