A patient with severe penicillin allergy (anaphylaxis) requires treatment for enterococcal endocarditis. The most appropriate cell-wall-active alternative to combine with an aminoglycoside for synergy is:
- A Vancomycin ✓
- B Cefazolin
- C Imipenem
- D Aztreonam
Correct answer: A. Vancomycin
Explanation
In true penicillin anaphylaxis, cephalosporins (including cefazolin) carry a small but real cross-reactivity risk and are generally avoided. Aztreonam is a monobactam with no cross-reactivity but has poor enterococcal coverage. Imipenem carries significant cross-reactivity risk. Vancomycin (a glycopeptide) inhibits cell wall synthesis by binding D-Ala-D-Ala without β-lactam structure, has no cross-reactivity with penicillin, and is the preferred cell-wall-active agent for enterococcal endocarditis in this setting, combined with gentamicin for synergy.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.