Beta-lactamase

A bacterial enzyme that hydrolyzes the beta-lactam ring of susceptible antibiotics, often inactivating them and contributing to antimicrobial resistance.

Beta-lactam ring: A four-membered cyclic amide found in penicillin, cephalosporin, and related antibiotics. Its hydrolysis is the defining reaction that lets beta-lactamases inactivate susceptible drugs.
Extended-spectrum beta-lactamase: A beta-lactamase that hydrolyzes many penicillins and cephalosporins, including extended-spectrum cephalosporins. Detecting these enzymes helps explain resistance to commonly used cephalosporins.
Penicillin: A group of beta-lactam antibiotics first discovered through the antibacterial effects of Penicillium mold. Penicillin use made bacterial enzymes that inactivate beta-lactams clinically consequential.
Antimicrobial resistance: The ability of microorganisms to survive or grow despite exposure to drugs that would ordinarily inhibit them. Beta-lactamases are one biochemical route by which bacteria resist antimicrobial drugs.
Serine beta-lactamase: A beta-lactamase that uses an active-site serine to form a transient covalent intermediate during hydrolysis. This enzyme group attacks the antibiotic through a serine-linked intermediate.
AmpC beta-lactamase: A cephalosporinase that can confer resistance to many penicillins and cephalosporins, including cephamycins. AmpC production changes which beta-lactam drugs can be relied on.
Abraham Edward Werner: A German microbiologist who reported penicillin-inactivating activity in bacteria in 1940. His report documented bacterial penicillinase before widespread penicillin treatment.
Horizontal gene transfer: The movement of genetic material between organisms by routes other than inheritance from parent to offspring. Transfer of beta-lactamase genes can spread resistance beyond bacterial descendants.
Metallo-beta-lactamase: A beta-lactamase that uses one or two zinc ions to activate water for antibiotic hydrolysis. Unlike serine enzymes, these enzymes use metal-activated water to break the drug’s ring.
Carbapenemase: A beta-lactamase that hydrolyzes carbapenems, a broad-spectrum class of beta-lactam antibiotics. Carbapenemase detection signals resistance to drugs often reserved for severe infections.

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