Which statement best describes the mechanism of action of aminoglycosides and a key toxicity?

Which statement best describes the mechanism of action of aminoglycosides and a key toxicity?

• A. Irreversibly bind the 30S ribosomal subunit causing misreading of mRNA; nephrotoxicity and ototoxicity are key toxicities.
• B. Inhibit dihydrofolate reductase; liver toxicity.
• C. Block peptidoglycan cross-linking; nephrotoxicity.
• D. Inhibit RNA polymerase; photosensitivity.

Answer: (A)

Aminoglycosides kill bacteria by irreversibly binding to the 30S ribosomal subunit, which misreads mRNA and produces faulty proteins. This disruption of protein synthesis is bactericidal. A hallmark toxicity is nephrotoxicity and ototoxicity, reflecting drug accumulation in kidney cells and inner-ear hair cells; this makes careful dosing and monitoring crucial, especially in patients with kidney impairment or on other nephrotoxic drugs. The other mechanisms listed pertain to different antibiotic classes—for example, dihydrofolate reductase inhibition (trimethoprim), peptidoglycan cross-linking inhibition (beta-lactams/vancomycin), or RNA polymerase inhibition (rifampin)—and do not describe aminoglycoside action or its primary toxicities.

Aminoglycosides kill bacteria by irreversibly binding to the 30S ribosomal subunit, which misreads mRNA and produces faulty proteins. This disruption of protein synthesis is bactericidal. A hallmark toxicity is nephrotoxicity and ototoxicity, reflecting drug accumulation in kidney cells and inner-ear hair cells; this makes careful dosing and monitoring crucial, especially in patients with kidney impairment or on other nephrotoxic drugs. The other mechanisms listed pertain to different antibiotic classes—for example, dihydrofolate reductase inhibition (trimethoprim), peptidoglycan cross-linking inhibition (beta-lactams/vancomycin), or RNA polymerase inhibition (rifampin)—and do not describe aminoglycoside action or its primary toxicities.