In empiric meningitis therapy, which drug is used to address potential penicillin-resistant Streptococcus pneumoniae?

• A. Dexamethasone
• B. Ceftriaxone
• C. Ampicillin
• D. Vancomycin

Answer: (D)

In meningitis you want to cover the organisms most likely to cause the illness, including strains of Streptococcus pneumoniae that may be resistant to penicillin. Penicillin resistance in pneumococcus arises when the bacteria alter their penicillin-binding proteins, reducing the effectiveness of beta-lactams. Vancomycin remains active against penicillin-resistant pneumococcus, and it achieves therapeutic levels in the CSF during meningeal inflammation. Adding vancomycin to the empiric regimen with a third-generation cephalosporin (like ceftriaxone) ensures coverage for resistant pneumococcus while awaiting susceptibility results. Dexamethasone is useful to lessen inflammatory damage in pneumococcal meningitis but doesn’t address resistance. Ceftriaxone alone covers many strains but may miss resistant ones, and ampicillin is included mainly to cover Listeria in older adults or certain patients, not specifically to counter penicillin-resistant pneumococcus.