Antimicrobials USMLE Step 1 Practice Question
A 7-year-old boy with no prior antibiotic allergies presents with a 3-day history of acute otitis media and is started on amoxicillin-clavulanate. On day 3 of therapy, his mother reports a widespread erythematous maculopapular rash affecting his trunk and extremities. The boy remains afebrile (37.2°C), and physical examination reveals no urticaria, angioedema, oral ulcers, or signs of systemic toxicity. Vital signs are stable: BP 105/68 mmHg, HR 92 bpm, RR 18, SpO2 98% on room air. Laboratory studies show WBC 8,200/μL with normal differential. The ear examination confirms resolving otitis media. Which of the following is the most appropriate management?
Answer choices
- AContinue amoxicillin-clavulanate with close clinical follow-up, as this is consistent with a benign drug rash that typically self-resolvesCorrect answer
- BDiscontinue amoxicillin-clavulanate immediately and initiate a macrolide antibiotic to treat the underlying infection
- CSwitch to a third-generation cephalosporin given the suspected beta-lactam hypersensitivity
- DAdminister diphenhydramine and continue amoxicillin-clavulanate, as the rash is likely urticarial and responsive to antihistamines
- EDiscontinue amoxicillin-clavulanate and initiate systemic corticosteroids for presumed drug reaction
- FPerform immediate skin testing and graded challenge testing before continuing any beta-lactam therapy
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.