Ambler class C serine beta-lactamase (AmpC) (AmpC)

Ambler class C serine beta-lactamase, commonly known as AmpC, is a bacterial enzyme that confers resistance to a wide range of beta-lactam antibiotics, including penicillins, cephamycins, and most cephalosporins (Bush & Jacoby, 2010). These enzymes utilize a catalytic serine residue to hydrolyze the beta-lactam ring, thereby inactivating the antibiotic before it can inhibit cell wall synthesis. AmpC enzymes are typically chromosomally encoded in many Gram-negative bacteria, such as Enterobacter, Citrobacter, and Pseudomonas aeruginosa, but can also be found on mobile plasmids (Meini et al., 2019). A significant clinical challenge is the ability of certain bacteria to 'induce' high-level production of the enzyme in response to antibiotic exposure, or to develop mutations leading to constitutive overproduction. Unlike Class A beta-lactamases, AmpC enzymes are not inhibited by traditional inhibitors like clavulanic acid or sulbactam. Consequently, treatment often requires the use of carbapenems or newer combinations involving non-beta-lactam inhibitors like avibactam or vaborbactam (Tamma et al., 2019).

Other names

AmpC beta-lactamaseClass C beta-lactamaseCephalosporinaseSerine-type beta-lactamase class C

Inhibition of the enzyme's active-site serine residue through covalent or non-covalent binding, preventing the hydrolysis of co-administered beta-lactam antibiotics (Bush & Jacoby, 2010).