Which combination constitutes the standard treatment for ocular toxoplasmosis?

• A. Sulfadiazine Plus Pyrimethamine
• B. Doxycycline Plus Rifampin
• C. Acyclovir
• D. Azithromycin

Answer: (A)

Treating ocular toxoplasmosis relies on two antiparasitic drugs that specifically disrupt the parasite’s folate synthesis, effectively halting replication. Pyrimethamine blocks the parasite’s dihydrofolate reductase, while sulfadiazine inhibits dihydropteroate synthase; together they prevent production of nucleotides the tachyzoites need to multiply. Because pyrimethamine can suppress the bone marrow, folinic acid (leucovorin) is given to protect the patient’s marrow while the parasite is being hit with the drug combo. In practice, this backbone is often complemented by a short course of systemic corticosteroids to control the inflammatory response once therapy has begun. Other regimens, like doxycycline with rifampin, acyclovir, or azithromycin, are not the standard first-line treatment for ocular toxoplasmosis because they lack reliable activity against Toxoplasma gondii.