Brain abscess

A 15-year-old girl is brought to the emergency department by her parents due to a sudden onset of seizure. The parents report that during the past few days, the patient has been feeling lethargic with fevers and constant headaches. Medical history is insignificant other than a progressive aching tooth pain the week before. The patient lives with her parents, 2 brothers, a cat, and a dog. Temperature is 38.6°C (101.48°F), pulse is 102/min, and blood pressure is 135/85 mmHg. On physical examination, the patient is postictal but arousable. She speaks fluently, but the words are incomprehensible. Meningeal signs are negative. MRI of the head reveals a ring-enhancing lesion occupying the frontal lobes. Which of the following pathogens is most likely responsible for this patient’s condition?