A 25-year-old HIV-positive male comes to a physician with complaints of headache and left-sided weakness of recent onset. His temperature is 38C (100.8F), blood pressure is 115/70mm Hg, respirations are 14/min, and pulse is 73/min. Neurological examination reveals decreased power, hyperreflexia, and upgoing plantars in the left upper and lower limb. Neuroimaging by CT shows multiple ring-enhancing lesions. What is the most appropriate next step in management?
A. Trimethoprim-sulfamethoxazole
B. Sulfadiazine and pyrimethamine
C. Brain irradiation
D. Brain biopsy
E. Anti-tuberculous therapy