Beta-lactamases are enzymes produced by bacteria that provide multi-resistance to beta-lactam antibiotics such as penicillins, cephalosporins, cephamycins, monobactams, and carbapenems. They break open the beta-lactam ring of these antibiotics, inactivating them. Some beta-lactamases are encoded on mobile genetic elements such as plasmids, while others are encoded on chromosomes.

Beta-lactamases can be classified into two categories: serine beta-lactamases and metallo-beta-lactamases. Serine beta-lactamases are grouped by sequence similarity into types A, C, and D. Metallo-beta-lactamases need metal ions such as zinc on their active site for their catalytic activities