A 28-year-old woman with a documented anaphylactic reaction to penicillin develops a complicated intra-abdominal infection caused by susceptible Gram-negative aerobes. Which cell wall synthesis inhibitor can be used safely in her?
- A Cefepime
- B Aztreonam ✓
- C Imipenem-cilastatin
- D Amoxicillin-clavulanate
Correct answer: B. Aztreonam
Explanation
Aztreonam is a monobactam whose monocyclic beta-lactam ring binds only the PBP3 of aerobic Gram-negative bacteria. Because it lacks the bicyclic nucleus shared by penicillins, cephalosporins and carbapenems, cross-reactivity in IgE-mediated penicillin allergy is negligible, making it the beta-lactam of choice in such patients. It has no activity against Gram-positive organisms and anaerobes, so it must be combined with metronidazole and an agent covering enterococci when those pathogens are suspected.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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