A 28-year-old man presents to the emergency department with a 2-day history of fever, severe headache, neck stiffness, and photophobia. Vital signs show temperature 39.8°C, blood pressure 118/74 mmHg, and heart rate 108/min. Physical examination reveals positive Kernig and Brudzinski signs. Lumbar puncture shows cloudy cerebrospinal fluid (CSF) with opening pressure 280 mmH₂O, white blood cell count 1,200 cells/mm³ (95% neutrophils), protein 180 mg/dL, and glucose 28 mg/dL (serum glucose 95 mg/dL). Empiric antimicrobial therapy is initiated with ceftriaxone 2 g IV every 12 hours, vancomycin 15-20 mg/kg IV every 8-12 hours, and dexamethasone. CSF culture subsequently grows Streptococcus pneumoniae sensitive to penicillin (MIC 0.06 mcg/mL). Blood cultures remain negative. Which of the following best explains the clinical rationale for including vancomycin in the empiric regimen for bacterial meningitis in this patient?

1. A)Vancomycin achieves higher absolute concentrations in CSF than ceftriaxone due to superior lipophilicity and blood-brain barrier penetration
2. B)Ceftriaxone monotherapy has inadequate CSF penetration and requires a synergistic agent to achieve bactericidal activity
3. C)The prevalence of penicillin-resistant and cephalosporin-resistant S. pneumoniae strains necessitates empiric dual therapy until susceptibilities are knownGABARITO
4. D)Vancomycin provides coverage against gram-negative organisms such as Neisseria meningitidis that cephalosporins cannot reach in the meninges
5. E)Early vancomycin administration reduces CSF inflammation and dexamethasone requirement in meningitis patients