Which gene is commonly targeted in MRSA detection by PCR?

Which gene is commonly targeted in MRSA detection by PCR?

• A. vanA
• B. ermC
• C. mecA
• D. blaZ

Answer: (C)

The test relies on identifying the genetic determinant that drives methicillin resistance in Staphylococcus aureus. The mecA gene encodes PBP2a, a penicillin-binding protein with very low affinity for beta-lactam antibiotics, which is what makes MRSA resistant. Detecting mecA by PCR in a Staphylococcus aureus isolate indicates MRSA. This gene is carried on the staphylococcal cassette chromosome mec (SCCmec), differentiating MRSA from susceptible strains. Other genes listed correspond to different resistance mechanisms: vanA for vancomycin resistance, ermC for macrolide resistance, and blaZ for beta-lactamase production, none of which alone define MRSA. In some rare strains, mecC can also confer resistance, but mecA remains the most widely used target. The gene commonly targeted for MRSA detection by PCR is mecA.

The test relies on identifying the genetic determinant that drives methicillin resistance in Staphylococcus aureus. The mecA gene encodes PBP2a, a penicillin-binding protein with very low affinity for beta-lactam antibiotics, which is what makes MRSA resistant. Detecting mecA by PCR in a Staphylococcus aureus isolate indicates MRSA. This gene is carried on the staphylococcal cassette chromosome mec (SCCmec), differentiating MRSA from susceptible strains. Other genes listed correspond to different resistance mechanisms: vanA for vancomycin resistance, ermC for macrolide resistance, and blaZ for beta-lactamase production, none of which alone define MRSA. In some rare strains, mecC can also confer resistance, but mecA remains the most widely used target. The gene commonly targeted for MRSA detection by PCR is mecA.