A 52-year-old man with a history of penicillin allergy (non-anaphylactic rash) presents with acute bacterial meningitis. CSF analysis shows elevated protein (180 mg/dL), low glucose (35 mg/dL), and positive Gram stain showing Gram-positive cocci in pairs. Blood cultures are pending. His renal function is normal (creatinine 0.9 mg/dL). Which of the following is the most appropriate antibiotic choice for this patient?