A neurologist requests antibiotic cover before craniotomy for a patient with a basilar meningitis suspected to be pneumococcal. The intensivist avoids imipenem-cilastatin and chooses meropenem instead. The decisive difference between these two carbapenems in this setting is:

• A Meropenem has superior CSF penetration compared with imipenem
• B Meropenem carries a much lower risk of seizures than imipenem at comparable doses ✓
• C Meropenem is stable to dehydropeptidase I, allowing higher brain tissue levels
• D Imipenem antagonizes concurrent empiric vancomycin used in meningitis regimens

Explanation

Both carbapenems penetrate inflamed meninges well, but imipenem is strongly epileptogenic because it binds GABA-A receptors competitively, and it lowers the seizure threshold especially at high doses or in renal impairment. Meropenem has minimal GABA affinity and is the preferred carbapenem for CNS infections including bacterial meningitis. Both drugs are inactivated by renal dehydropeptidase I and both are paired with cilastatin or engineered for stability, so that distinction does not separate them here.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.