Mechanism of action of gentamicin
**Core Concept**
Gentamicin is an aminoglycoside antibiotic that exhibits bactericidal activity against a wide range of Gram-negative bacteria. It acts by inhibiting protein synthesis through a specific mechanism of action.
**Why the Correct Answer is Right**
Gentamicin binds to the 30S subunit of the bacterial ribosome, specifically to the A site. This binding causes misreading of messenger RNA (mRNA) during translation, leading to the incorporation of incorrect amino acids into the growing polypeptide chain. As a result, the bacterial cell is unable to produce functional proteins, ultimately leading to cell death. This mechanism of action is unique to aminoglycoside antibiotics.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because gentamicin does not inhibit DNA replication or transcription. Aminoglycosides do not interfere with DNA or RNA synthesis.
**Option B:** Incorrect because gentamicin does not act by disrupting cell wall synthesis. This mechanism is characteristic of beta-lactam antibiotics, such as penicillins and cephalosporins.
**Option C:** Incorrect because gentamicin does not inhibit the electron transport chain. This mechanism is associated with antimicrobial agents that target mitochondrial function, such as antifungals.
**Clinical Pearl / High-Yield Fact**
Aminoglycosides like gentamicin can cause nephrotoxicity and ototoxicity as side effects, particularly with prolonged use or high doses. It's essential to monitor renal function and auditory thresholds in patients receiving these antibiotics.
**Correct Answer: B. Inhibiting protein synthesis through binding to the 30S ribosomal subunit.**