For patients older than 50 years with suspected bacterial meningitis, which regimen is recommended?

• A. Ceftriaxone alone.
• B. Ampicillin plus Ceftriaxone (or Cefotaxime) with or without Vancomycin.
• C. Ampicillin alone.
• D. Vancomycin alone.

Answer: (B)

In adults over 50, bacterial meningitis pathogens include Listeria monocytogenes, which is not reliably covered by cephalosporins alone. That’s why empiric therapy must add ampicillin to cover Listeria, while a third-generation cephalosporin (ceftriaxone or cefotaxime) covers the common pathogens like Streptococcus pneumoniae and Neisseria meningitidis. Vancomycin can be added if there’s concern for penicillin- or cephalosporin-resistant pneumococcus. This combination—ampicillin plus a third-generation cephalosporin, with vancomycin if indicated—provides broad, appropriate coverage while awaiting culture results. Dexamethasone might be used adjunctively, especially in suspected pneumococcal meningitis, but the antibiotic plan is aimed at covering the likely organisms in older adults.