Beta-lactamase class A and beta-lactamase class C enzyme (Class A β-lactamase, Class C β-lactamase)

Beta-lactamase class A and beta-lactamase class C enzymes are bacterial serine hydrolases responsible for inactivating β-lactam antibiotics, such as penicillins and cephalosporins, by hydrolyzing their characteristic four-membered β-lactam ring. Class A β-lactamases include penicillinases, some cephalosporinases, and extended-spectrum β-lactamases (ESBLs), which confer resistance to a broad range of β-lactams and are generally inhibited by active-site inhibitors like clavulanic acid. Class C β-lactamases, commonly called AmpC enzymes or cephalosporinases, primarily hydrolyze cephalosporins (including some expanded-spectrum agents) and are not effectively inhibited by traditional β-lactamase inhibitors like clavulanic acid, but can be inhibited by newer agents such as avibactam. These enzymes are major contributors to antibiotic resistance in clinically important Gram-negative bacteria and represent priority therapeutic targets for infection control.

Other names

Class A serine β-lactamaseClass C cephalosporinaseSerine β-lactamase (for A and C)AmpC β-lactamase (for class C)ESBL (extended-spectrum β-lactamase, for some class A)Cephalosporinase (for class C)

Hydrolysis (inactivation) of the β-lactam ring in antibiotics, leading to antibiotic resistance. Drugs (β-lactamase inhibitors) target and inhibit these enzymes to restore antibiotic efficacy