Ceftaroline is a fifth-generation cephalosporin with activity against MRSA. Its mechanism compared to earlier cephalosporins is BEST explained by:
- A Beta-lactamase inhibition combined with beta-lactam antibacterial activity
- B High binding affinity for the modified PBP2a (PBP2') expressed by MRSA ✓
- C Disruption of bacterial cell membrane integrity via lipophilic interactions
- D Inhibition of D-Ala-D-Ala ligase preventing peptidoglycan precursor synthesis
Correct answer: B. High binding affinity for the modified PBP2a (PBP2') expressed by MRSA
Explanation
MRSA resistance to beta-lactams is due to expression of PBP2a (encoded by mecA), which has very low affinity for conventional beta-lactams. Ceftaroline has a unique side chain that allows it to bind PBP2a with high affinity, inhibiting its transpeptidase activity. It is not a beta-lactamase inhibitor, does not act on cell membranes, and does not target D-Ala-D-Ala ligase (which is vancomycin's mechanism).
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.