Final answer:
The most frequent opportunistic CNS infection in AIDS patients is Cryptococcal meningitis. It is caused by Cryptococcus neoformans, a fungal pathogen commonly found in soils and associated with pigeon droppings. Treatment involves prolonged therapy with antifungal drugs.
Step-by-step explanation:
The most frequent opportunistic CNS infection in AIDS patients is Cryptococcal meningitis. Cryptococcus neoformans is a fungal pathogen commonly found in soils and associated with pigeon droppings. It can cause meningitis and granuloma formation in brain tissues, particularly in immunocompromised individuals. Treatment of cryptococcal infections requires prolonged therapy with antifungal drugs, and AIDS patients may need lifelong doses of fluconazole to prevent reinfection.