MRSA is differentiated from methicillin-susceptible S. aureus (MSSA) by the presence of a specific gene encoding a modified penicillin-binding protein. Which PBP is responsible for MRSA resistance?
- A PBP1 encoded by pbp1 gene
- B PBP2a encoded by mecA gene ✓
- C PBP3 encoded by ftsI gene
- D PBP4 encoded by pbp4 gene
Correct answer: B. PBP2a encoded by mecA gene
Explanation
mecA encodes PBP2a (also called PBP2'), a modified penicillin-binding protein with very low affinity for all beta-lactam antibiotics, conferring resistance to the entire class. Detection is achieved by latex agglutination for PBP2a or PCR for mecA. mecC is an alternative gene conferring similar resistance detected by some community-acquired MRSA strains but mecA is the primary target. PBP3 mutations confer cephalosporin resistance in H. influenzae, not MRSA.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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