β-lactamase inhibitors:

β-lactamase inhibitors are β-lactam compounds that lack significant antibacterial activity but potentiate tha activity of classical β-lactamase-sensitive antibiotics by protecting them from the hydrolytic activity of the
β-lactamase (Bush, 1988). They include clavulanic acid, the penam sulfones sulbactam and tazobactam, and new compounds such as BRL 42715. Of these compounds, clavulanic acid, sulbactam, and tazobactam are currently in clinical use.

Regarding the inhibiting activity of β-lactamase inhibitors; clavulanic acid, tazobactam and sulbactam are more inhibitory to class A than class C β-lactamases . For class A β-lactamases, clavulanic acid and tazobactam show similar activities against TEM-1 and TEM-2, and the Staphylococcal enzymes. Sulbactam is the least potent inhibitor of class A enzymes, compared with clavulanic acid and tazobactam (Payne et al., 1994). The metal chelators are the only available inhibitors of class B β-lactamses.

Regarding class C β-lactamases, clavulanic acid is a very weak inhibitor whereas sulbactam and tazobactam are potent inhibitors. On the other hand, the inhibitory potency of all inhibitors is weak against class D
β-lactamases (Payne et al., 1994).