The medium of choice for culturing yeast form of dimorphic fungi is –
**Core Concept**
Dimorphic fungi are a type of fungal pathogens that can exist in both yeast and filamentous forms, depending on the environmental conditions. The yeast form of these fungi is often cultured in the laboratory to diagnose infections. The medium used for culturing these fungi should support their growth in the yeast form.
**Why the Correct Answer is Right**
The correct medium for culturing the yeast form of dimorphic fungi is Sabouraud dextrose agar (SDA) with 5% blood. This medium provides the necessary nutrients for the growth of these fungi, including the dextrose as a carbon source and the blood as a source of nutrients. The yeast form of dimorphic fungi, such as *Histoplasma capsulatum* and *Blastomyces dermatitidis*, can be isolated from clinical specimens using this medium. The blood in the medium also helps to support the growth of these fungi by providing a source of iron and other essential nutrients.
**Why Each Wrong Option is Incorrect**
* **Option A:** Löwenstein-Jensen agar is used for culturing *Mycobacterium tuberculosis*, not dimorphic fungi.
* **Option B:** MacConkey agar is used for culturing Gram-negative bacteria, not fungi.
* **Option C:** Chocolate agar is used for culturing *Haemophilus* species and *Neisseria* species, not dimorphic fungi.
**Clinical Pearl / High-Yield Fact**
Dimorphic fungi can be classified into two main groups: thermally dimorphic fungi, which grow as molds at room temperature and as yeasts at body temperature, and cold-dimorphic fungi, which grow as molds at room temperature and as yeasts at lower temperatures.
**Correct Answer:** C.