Which of the following best describes the primary bactericidal mechanism of aminoglycosides such as gentamicin?
- A Binding the 50S ribosomal subunit and blocking translocation of peptidyl-tRNA
- B Inhibition of DNA gyrase leading to failure of chromosome replication
- C Irreversible binding to the 30S ribosomal subunit causing misreading of mRNA ✓
- D Competitive inhibition of dihydrofolate reductase, halting folate synthesis
Correct answer: C. Irreversible binding to the 30S ribosomal subunit causing misreading of mRNA
Explanation
Aminoglycosides bind irreversibly to the 30S subunit, specifically the 16S rRNA component of the 30S decoding region, causing misreading of the mRNA codon sequence and incorporation of wrong amino acids, producing nonfunctional proteins. Option A describes macrolides and chloramphenicol at the 50S subunit, option B describes fluoroquinolones, and option D describes trimethoprim.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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