Class D β-lactamase (OXA-type) (OXA β-lactamase)

OXA β-lactamases are a family of class D serine-based enzymes, conventionally named for their oxacillinase activity, that hydrolyze and inactivate β-lactam antibiotics such as penicillins, cephalosporins, and carbapenems. They are widely distributed among Gram-negative bacteria, often encoded by transferable plasmids as well as chromosomes, notably in ESKAPE pathogens. These enzymes are poorly inhibited by many standard β-lactamase inhibitors, with over 750 known variants conferring potentially both narrow- and extended-spectrum resistance. Some lipidated OXA β-lactamases, particularly in Acinetobacter spp., localize to the membrane and play significant roles in high-level antibiotic resistance. Their substrate specificity and catalytic mechanisms are structurally distinguished by a conserved Ser-x-x-Lys motif and a carboxylated lysine in the active site, making them challenging therapeutic targets in multidrug-resistant infections[1][2][3][4][5]. If specificity for a single variant is needed (e.g., OXA-23), more detailed names and function can be given, but "OXA β-lactamase" covers the therapeutically relevant class D β-lactamase enzymes responsible for much of current β-lactam resistance.

Other names

OXA-type β-lactamaseoxacillinaseclass D β-lactamaseOXA enzyme

Drug hydrolysis (breaking the β-lactam ring, rendering antibiotics inactive); Confers resistance by enzymatically inactivating β-lactam antibiotics[3][4]