Aztreonam can be safely administered to most patients with a documented severe penicillin allergy, EXCEPT those who have had reactions to one particular beta-lactam because of a shared side chain. That agent is:
- A Amoxicillin
- B Ceftazidime ✓
- C Ceftriaxone
- D Nafcillin
Correct answer: B. Ceftazidime
Explanation
Aztreonam shares an identical side chain with ceftazidime, so immunologic cross-reactivity between these two agents has been reported and aztreonam should be avoided in patients with ceftazidime allergy. Cross-reactivity between aztreonam and other beta-lactams including penicillins and other cephalosporins is negligible because the monocyclic monobactam ring differs structurally from the bicyclic beta-lactam nucleus shared by the others.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.