Neurotropic fungus is/are -a) Cryptococcus neoformansb) Histoplasmosisc) Trichophytond) Candidae) Aspergillosis
## Core Concept
The question tests knowledge of fungi that have a predilection for infecting the nervous system, known as neurotropic fungi. These pathogens can cause severe and potentially life-threatening infections, particularly in immunocompromised individuals.
## Why the Correct Answer is Right
Cryptococcus neoformans is a well-known neurotropic fungus that primarily causes cryptococcal meningitis, especially in patients with weakened immune systems, such as those with HIV/AIDS. This fungus has a specific affinity for the central nervous system (CNS), making it a classic example of a neurotropic pathogen.
## Why Each Wrong Option is Incorrect
* **Option B: Histoplasmosis** - While Histoplasma capsulatum can disseminate to various organs, including the CNS, it is not as specifically neurotropic as Cryptococcus neoformans. It is primarily known for causing lung infections.
* **Option C: Trichophyton** - This genus of fungi is primarily associated with dermatophyte infections (e.g., athlete's foot, jock itch), not with neurotropic infections.
* **Option D: Candida** - Candida species can cause a variety of infections, including bloodstream infections and disseminated infections in immunocompromised hosts. While it can involve the CNS, it is not specifically classified as a neurotropic fungus.
* **Option E: Aspergillosis** - Aspergillus species can cause invasive aspergillosis, which can involve the CNS, particularly in immunocompromised patients. However, like Candida, it is not specifically termed a neurotropic fungus.
## Clinical Pearl / High-Yield Fact
A key point to remember is that Cryptococcus neoformans is a leading cause of fungal meningitis, particularly in immunocompromised patients. Its polysaccharide capsule is a major virulence factor, and the India ink stain can help visualize the capsule in clinical specimens.
## Correct Answer: A. Cryptococcus neoformans