Drug of choice for MRSA is
**Core Concept**
Vancomycin is the first-line treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections due to its potent antibacterial activity against this multidrug-resistant pathogen. Vancomycin exerts its effects by inhibiting cell wall synthesis in MRSA bacteria, ultimately leading to bacterial lysis and death.
**Why the Correct Answer is Right**
Vancomycin binds to the D-alanyl-D-alanine (D-Ala-D-Ala) terminus of cell wall precursors, preventing the incorporation of these precursors into the bacterial cell wall. This action ultimately leads to the accumulation of cell wall precursors and the depletion of the cell wall, causing the bacterial cell to lyse and die. Vancomycin is effective against MRSA due to its ability to target the bacterial cell wall, a site that is essential for bacterial survival.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is not a correct answer because it does not accurately reflect the preferred treatment for MRSA infections.
**Option B:**
This option is incorrect because while it is a commonly used antibiotic, it is not the preferred treatment for MRSA due to concerns regarding resistance and efficacy.
**Option C:**
This option is incorrect because it is not a commonly used antibiotic for the treatment of MRSA infections, and its use may be associated with significant toxicity.
**Clinical Pearl / High-Yield Fact**
Vancomycin is a glycopeptide antibiotic that is effective against MRSA due to its unique mechanism of action, which involves the inhibition of cell wall synthesis. This mechanism of action makes vancomycin an essential treatment option for MRSA infections, particularly in patients who have failed treatment with other antibiotics.
**Correct Answer: D. Vancomycin.**