Final answer:
Individuals with compromised immune systems are at higher risk of developing Pneumocystis pneumonia or cryptococcosis, with potentially fatal outcomes if untreated. Pneumocystis pneumonia is treated with drugs like trimethoprim-sulfamethoxazole, while cryptococcosis requires a combination of antifungals. Toxoplasma gondii infections are treated with a specific drug regimen.
Step-by-step explanation:
Prophylaxis and Treatment of Opportunistic Infections
The populations most at risk for developing Pneumocystis pneumonia (PCP) or cryptococcosis are individuals with compromised immune systems, such as patients with AIDS, and other immunocompromised individuals including those on chemotherapy or with organ transplants. These infections are particularly fatal if left untreated because they can lead to severe respiratory failure or central nervous system complications. For PCP, caused by the fungus Pneumocystis jirovecii, the first line of treatment is typically the combination drug trimethoprim-sulfamethoxazole (TMP/SMZ), with alternatives such as atovaquone or pentamidine.
Cryptococcis, caused by Cryptococcus neoformans, often requires a regimen of amphotericin B and flucytosine, followed by fluconazole to clear the fungus thoroughly. Meanwhile, infections from Toxoplasma gondii, leading to neurotoxoplasmosis, demand a treatment of pyrimethamine, sulfadiazine, and folinic acid.