Antimicrobials USMLE Step 1 Practice Question
A 58-year-old man with no known drug allergies presents to the operating room for elective right inguinal hernia repair under general anesthesia. He receives cefazolin 1 g IV 30 minutes before incision for surgical prophylaxis. Within 15 minutes, he develops hypotension (82/50 mmHg, baseline 128/76), tachycardia (118 bpm), hypoxemia (SpO2 91% on room air), diffuse urticaria, periorbital and lip edema, and inspiratory stridor. Epinephrine 0.3 mg IM is administered with clinical improvement. The procedure is postponed. Serum-specific IgE antibodies to cefazolin are confirmed on formal allergy testing. The patient will require antibiotics for a future surgical procedure. Which of the following best describes the relationship between cefazolin hypersensitivity and the safety profile of other beta-lactam agents in this patient?
Answer choices
- AAll penicillins and cephalosporins are absolutely contraindicated; only fluoroquinolones or macrolides should be used
- BThird-generation cephalosporins (ceftriaxone, cefotaxime) have minimal cross-reactivity risk (<3%) and can be used with appropriate monitoringCorrect answer
- CFirst-generation cephalosporins share an identical R-group side chain with penicillins and must be avoided, but second-generation agents are safe
- DPenicillins are safe because cephalosporin allergy is always related to contaminating penicillin from manufacturing, not the cephalosporin itself
- EMeropenem (carbapenem) is contraindicated due to identical beta-lactam ring structure, but aztreonam can be safely substituted
- FAll beta-lactams can be safely used following oral desensitization with amoxicillin at home prior to surgery
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.