Concept
Beta-lactamase
Enzyme that breaks the beta-lactam ring
BAY-tuh-LAK-tuh-mays
High-yield clue
Beta-lactamase inactivates penicillins by hydrolyzing (cleaving) the beta-lactam ring before the drug can act.
Overview
A bacterial enzyme that hydrolyzes the beta-lactam ring of penicillins and related drugs, inactivating them. It is the most common enzymatic mechanism of resistance to beta-lactam antibiotics.
Classification
- Hydrolytic enzyme
- Serine or metallo (zinc) active site
- Ambler classes A-D
- Chromosomal or plasmid-encoded
Lab & identification clues
- Penicillinase vocabulary
- Serine vs metallo-beta-lactamase concept
- Beta-lactamase-inhibitor combination vocabulary
Associations
- Penicillin and cephalosporin inactivation
- Basis of ESBL and carbapenemase framing
- Often plasmid-transmissible
Commonly confused with
- Altered PBP (mecA) resistance
- Porin loss
Frequently asked questions
What is Beta-lactamase?
A bacterial enzyme that hydrolyzes the beta-lactam ring of penicillins and related drugs, inactivating them. It is the most common enzymatic mechanism of resistance to beta-lactam antibiotics.
What is the high-yield clue for Beta-lactamase?
Beta-lactamase inactivates penicillins by hydrolyzing (cleaving) the beta-lactam ring before the drug can act.
What is Beta-lactamase associated with?
Beta-lactamase is associated with Penicillin and cephalosporin inactivation, Basis of ESBL and carbapenemase framing, and Often plasmid-transmissible.
What is Beta-lactamase commonly confused with?
Beta-lactamase is commonly confused with Altered PBP (mecA) resistance and Porin loss.
Original microbiology concept summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC/WHO topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment selection, infection-control instructions, or specimen-handling guidance.