In adults with suspected bacterial meningitis, what is the standard empiric therapy before culture results?

• A. Vancomycin plus a third-generation cephalosporin; add ampicillin for Listeria coverage in patients ≥50 years or immunocompromised.
• B. Dexamethasone alone.
• C. Cefepime monotherapy.
• D. Penicillin G only.

Answer: (A)

When adults present with suspected bacterial meningitis, start broad empiric antibiotics right away to cover the most likely organisms and resistant strains until culture results arrive. The preferred approach is vancomycin plus a third-generation cephalosporin (such as ceftriaxone or cefotaxime) to cover Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. Ampicillin is added for Listeria monocytogenes coverage in patients aged 50 or older or who are immunocompromised, because Listeria is not reliably killed by cephalosporins. Dexamethasone can be given as an adjunct with the first dose of antibiotics to reduce inflammatory injury, but it does not replace the antibiotic regimen. Other options lack the necessary breadth or timing, either missing Listeria coverage or relying on a single agent that won’t adequately treat common meningitis pathogens.