Which statement best describes the bactericidal action of aminoglycosides such as gentamicin?
- A Binding to the 50S ribosomal subunit and blocking peptidyl transferase
- B Binding to the 30S ribosomal subunit, causing misreading of mRNA and inhibition of initiation complex formation ✓
- C Inhibition of DNA-dependent RNA polymerase
- D Blocking the A site and preventing aminoacyl-tRNA binding
Correct answer: B. Binding to the 30S ribosomal subunit, causing misreading of mRNA and inhibition of initiation complex formation
Explanation
Aminoglycosides bind irreversibly to multiple sites on the 30S subunit and associated proteins, causing misreading of mRNA (incorrect amino acid insertion) and blocking formation of the initiation complex. Option D describes tetracyclines, which bind 30S but prevent aminoacyl-tRNA attachment without causing misreading. Options A and C describe chloramphenicol/macrolides and rifampin respectively.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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