Antimicrobials USMLE Step 1 Practice Question
A 7-year-old boy presents with acute otitis media (BP 105/68, HR 98, RR 22, Temp 38.5°C). Otoscopy reveals erythematous tympanum with fluid level; tympanometry confirms type B pattern. He is prescribed amoxicillin and has no reported penicillin allergy. The drug exerts its antibacterial effect by binding penicillin-binding proteins and inhibiting peptidoglycan cross-linking in the bacterial cell wall. Which of the following best describes the consequence of this mechanism of action?
Answer choices
- AInhibition of 30S ribosomal translocation
- BDisruption of ergosterol synthesis in fungal membranes
- CActivation of autolytic enzymes leading to bacterial lysisCorrect answer
- DBlockade of folate synthesis through dihydropteroate synthase inhibition
- ECreation of DNA strand breaks by free radicals
- FPrevention of bacterial flagellar protein assembly and motility
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