What is the morphological sign indicative of coccidiomycosis observed under microscopy?

What is the morphological sign indicative of coccidiomycosis observed under microscopy?

• A. Hyphae
• B. Spherules
• C. Mycelium
• D. Pus cells

Answer: (B)

Coccidioidomycosis is caused by the fungus Coccidioides immitis (or Coccidioides posadasii), which is endemic to certain regions, particularly the southwestern United States. Upon microscopic examination of infected tissue or fluids, the characteristic morphological sign indicative of coccidioidomycosis is the presence of spherules. These spherules are large, round structures that can be found within tissue samples, filled with endospores. When the spherule ruptures, it releases these endospores, which can then develop into new spherules. This lifecycle within the host distinguishes coccidioidomycosis from other fungal infections that may present with different morphological features. In contrast, the other options reflect forms associated with different fungi or cellular responses. Hyphae are typically seen in mold infections, mycelium is indicative of fungal growth outside of specific pathogens, and pus cells represent the body's inflammatory response to infection rather than a distinctive characteristic of the fungal pathogen itself. Therefore, the observation of spherules under microscopy is a definitive diagnostic feature of coccidioidomycosis.

Coccidioidomycosis is caused by the fungus Coccidioides immitis (or Coccidioides posadasii), which is endemic to certain regions, particularly the southwestern United States. Upon microscopic examination of infected tissue or fluids, the characteristic morphological sign indicative of coccidioidomycosis is the presence of spherules.

These spherules are large, round structures that can be found within tissue samples, filled with endospores. When the spherule ruptures, it releases these endospores, which can then develop into new spherules. This lifecycle within the host distinguishes coccidioidomycosis from other fungal infections that may present with different morphological features.

In contrast, the other options reflect forms associated with different fungi or cellular responses. Hyphae are typically seen in mold infections, mycelium is indicative of fungal growth outside of specific pathogens, and pus cells represent the body's inflammatory response to infection rather than a distinctive characteristic of the fungal pathogen itself. Therefore, the observation of spherules under microscopy is a definitive diagnostic feature of coccidioidomycosis.