Question

The mechanism of bacterial resistance to penicillins via beta-lactamase is:

• A. Altered penicillin-binding proteins
• B. Drug efflux
• C. Breaks drug structure
• D. Alteration in 50S ribosome structure

Hint:

The enzyme name tells you it hydrolyses the beta-lactam ring.

Answer 1

The Correct Option is C

Name-the-enzyme logic: The clue is in the word beta-lactamase, an enzyme that acts on the beta-lactam ring. Enzymes that end in -ase cleave the target intact only by breaking it, so this is a drug-destroying mechanism.
Beta-lactamase hydrolyses (cleaves) the beta-lactam ring of penicillins. Since that ring is what binds PBPs to stop cell wall synthesis, cutting it inactivates the antibiotic, the drug structure is broken. That makes option C correct.
Distinguish the distractors, which are other resistance routes: altered PBPs with low drug affinity (MRSA, pneumococci), efflux pumps that pump the drug out (tetracyclines), and ribosomal target changes (aminoglycosides, macrolides) that have nothing to do with beta-lactamases.
Pearl: beta-lactamase = enzymatic destruction; clavulanate, sulbactam and tazobactam are added to protect the ring.
Ref: K. D. Tripathi, 7th Edition, beta-lactam antibiotics.