True about aminoglycosides is all except.
**Core Concept**
Aminoglycosides are a class of antibiotics that inhibit bacterial protein synthesis by binding to the 30S subunit of the bacterial ribosome. They are primarily used to treat severe bacterial infections, including those caused by gram-negative bacteria.
**Why the Correct Answer is Right**
Aminoglycosides work by binding to the 30S subunit of the bacterial ribosome, which leads to misreading of mRNA and premature termination of protein synthesis. This results in the death of the bacterial cell. Aminoglycosides are also known to cause damage to the renal tubular cells and the inner ear, which can lead to nephrotoxicity and ototoxicity, respectively.
**Why Each Wrong Option is Incorrect**
**Option A:** Aminoglycosides act by inhibiting cell wall synthesis. This is incorrect as aminoglycosides do not affect the bacterial cell wall synthesis, but rather inhibit protein synthesis by binding to the 30S subunit of the ribosome.
**Option B:** Aminoglycosides are primarily used to treat gram-positive infections. This is incorrect as aminoglycosides are primarily used to treat gram-negative infections, although they can be used in combination with other antibiotics to treat gram-positive infections.
**Option C:** Aminoglycosides are not nephrotoxic. This is incorrect as aminoglycosides are known to cause nephrotoxicity, particularly with prolonged use.
**Option D:** Aminoglycosides are effective against anaerobic bacteria. This is incorrect as aminoglycosides are primarily effective against aerobic and facultative anaerobic bacteria, but not against strict anaerobes.
**Clinical Pearl / High-Yield Fact**
Aminoglycosides should be used with caution in patients with pre-existing renal impairment, as they can exacerbate renal dysfunction. Additionally, aminoglycosides should be monitored for ototoxicity, particularly in patients with pre-existing hearing loss.
**Correct Answer: B. Aminoglycosides are primarily used to treat gram-positive infections.