In adults over 50 with suspected bacterial meningitis, which empiric antibiotic regimen is recommended?

• A. Vancomycin alone
• B. Vancomycin plus a third-generation cephalosporin with ampicillin
• C. Ceftriaxone alone
• D. Ampicillin alone

Answer: (B)

Empiric meningitis therapy in adults over 50 must cover Listeria monocytogenes as well as the common meningitis pathogens like Streptococcus pneumoniae and Neisseria meningitidis. Vancomycin adds protection against resistant pneumococcus; a third-generation cephalosporin covers Neisseria meningitidis and many pneumococci; and ampicillin specifically targets Listeria. Combining vancomycin with a third-generation cephalosporin and ampicillin provides broad initial coverage until culture results come back. Regimens with vancomycin alone miss Listeria; a third-generation cephalosporin alone misses Listeria; and ampicillin alone misses the other pathogens and potential resistant pneumococcus.