Class C β-lactamase (AmpC) (AmpC)

Class C β-lactamases, commonly known as AmpC enzymes, are a group of serine-based hydrolases that confer resistance to a broad range of β-lactam antibiotics in Gram-negative bacteria (Jacoby, 2009, Clinical Microbiology Reviews). These enzymes are primarily found in organisms such as Enterobacter cloacae, Citrobacter freundii, and Pseudomonas aeruginosa, where they can be encoded on the chromosome or on mobile plasmids (Meini et al., 2019, Journal of Antimicrobial Chemotherapy). AmpC enzymes are characterized by their ability to hydrolyze penicillins, third-generation cephalosporins, and monobactams, while remaining largely unaffected by traditional inhibitors like clavulanic acid or tazobactam (Bush & Bradford, 2016, Cold Spring Harbor Perspectives in Medicine). The expression of chromosomal AmpC is often inducible by certain antibiotics, and mutations in regulatory genes can lead to "derepression," resulting in high-level constitutive enzyme production and clinical treatment failure (Tamma et al., 2019, Open Forum Infectious Diseases). Modern therapeutic approaches utilize novel β-lactamase inhibitors, such as avibactam, relebactam, and vaborbactam, which effectively inhibit AmpC and restore the activity of partner antibiotics (Bush & Bradford, 2016). These enzymes represent a significant challenge in infectious disease management due to their broad substrate profile and the potential for rapid selection of resistant mutants during therapy.

Other names

AmpCAmpC β-lactamaseAmbler Class C β-lactamaseClass C cephalosporinaseCMY-type β-lactamaseDHA-type β-lactamaseFOX-type β-lactamaseMOX-type β-lactamaseACC-type β-lactamaseACT-type β-lactamaseMIR-type β-lactamase

Inhibition of the enzyme's catalytic activity through covalent or non-covalent binding to the active-site serine residue, thereby preventing the hydrolysis of the β-lactam ring in partner antibiotics (Bush & Bradford, 2016, Cold Spring Harbor Perspectives in Medicine).