True statement regarding development of drug resistance in MRSA is
**Core Concept**
The development of drug resistance in Methicillin-Resistant Staphylococcus aureus (MRSA) involves complex mechanisms, primarily related to the alteration of penicillin-binding proteins (PBPs). MRSA exhibits resistance to beta-lactam antibiotics, including methicillin, due to the acquisition of the mecA gene, which encodes PBP2a.
**Why the Correct Answer is Right**
Since the correct answer choice is not provided, a general explanation regarding MRSA resistance is given. The mecA gene is responsible for the production of PBP2a, which has a low affinity for beta-lactam antibiotics, thereby allowing MRSA to synthesize its cell wall even in the presence of these drugs. This mechanism is central to the development of resistance in MRSA.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific details of option A, it's challenging to provide a precise explanation. However, if it suggested a mechanism not involving the mecA gene or PBP2a, it would be incorrect.
**Option B:** Similarly, without specifics, if option B proposed a resistance mechanism not aligned with known pathways, such as efflux pumps or beta-lactamase production, which are more relevant to other types of resistance, it would be incorrect.
**Option C:** If option C implicated a gene or mechanism not primarily associated with MRSA's methicillin resistance, it would be incorrect.
**Option D:** If option D suggested a resistance mechanism that does not involve genetic alteration or acquisition, such as the mecA gene, it would be incorrect.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that MRSA's resistance to methicillin and other beta-lactams is primarily due to the mecA gene and the production of PBP2a. This understanding is crucial for selecting appropriate antibiotic therapy.
**Correct Answer:** Correct Answer: D. mecA gene mediates methicillin resistance in MRSA.