Pneumonia USMLE Step 1 Practice Question

A 19-year-old previously healthy male college student presents to the emergency department with a 2-day history of fever, severe headache, and neck stiffness. He reports that this morning he developed a productive cough with purulent sputum. Vital signs are: temperature 39.5°C, heart rate 108/min, blood pressure 122/78 mmHg, respiratory rate 20/min, and oxygen saturation 97% on room air. Physical examination reveals nuchal rigidity and a petechial rash on his trunk and lower extremities. Chest X-ray shows a left lower lobe consolidation. Lumbar puncture yields cerebrospinal fluid with protein 145 mg/dL, glucose 32 mg/dL (serum glucose 98 mg/dL), and elevated opening pressure. Which of the following organisms is most likely responsible for this patient's concurrent meningitis and pneumonia?