Question:
The mechanism of bacterial resistance to penicillins via beta-lactamase is:
The mechanism of bacterial resistance to penicillins via beta-lactamase is:
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The enzyme name tells you it hydrolyses the beta-lactam ring.
Updated On: Jun 23, 2026
- Altered penicillin-binding proteins
- Drug efflux
- Breaks drug structure
- Alteration in 50S ribosome structure
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The Correct Option is C
Solution and Explanation
Step 1: Beta-lactam antibiotics share a beta-lactam ring, which is essential for binding penicillin-binding proteins (PBPs) and blocking cell wall cross-linking.
Step 2: Beta-lactamases are bacterial enzymes (from staphylococci, Haemophilus, gonococci and others) that hydrolyse and open this beta-lactam ring. Once the ring is broken, the drug structure is destroyed and the antibiotic is inactivated before it can reach the PBPs.
Step 3: So beta-lactamase resistance works by breaking the drug structure (option C). The other listed options are separate resistance mechanisms: altered PBPs (as in MRSA), drug efflux pumps, and ribosomal alteration (which affects protein-synthesis inhibitors, not beta-lactams). Hence option C is correct.
Ref: K. D. Tripathi, 7th Edition, Pages 717-720.
Step 2: Beta-lactamases are bacterial enzymes (from staphylococci, Haemophilus, gonococci and others) that hydrolyse and open this beta-lactam ring. Once the ring is broken, the drug structure is destroyed and the antibiotic is inactivated before it can reach the PBPs.
Step 3: So beta-lactamase resistance works by breaking the drug structure (option C). The other listed options are separate resistance mechanisms: altered PBPs (as in MRSA), drug efflux pumps, and ribosomal alteration (which affects protein-synthesis inhibitors, not beta-lactams). Hence option C is correct.
Ref: K. D. Tripathi, 7th Edition, Pages 717-720.
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