Review Question - QID 214729

An 8-year-old boy is brought to the emergency department for worsening irritability and confusion for the past day. He has high-grade fevers, chills, and neck pain for the past 3 days. His temperature is 103.5°F (39.4°C), blood pressure is 95/55 mmHg, pulse is 110/min, and respirations are 25/min. He was born at term with no complications. He has not seen a physician for several years and is not up to date on his vaccinations. On physical examination, the boy appears lethargic. He is confused and oriented to person and place but not time. He has neck rigidity, and the cervical range of motion is limited by pain. The remainder of the physical exam shows no abnormalities. Laboratory studies demonstrate:

Hemoglobin: 10.3 g/dL
Leukocyte count: 16,000/mm^3
Platelet count: 200,000/mm^3

Blood cultures and a lumbar puncture are obtained. A peripheral smear is performed and the results are shown in Figure A. Which of the following pathogens is the most likely cause of this patient’s symptoms?