Sulbactam is a B lactamase inhibitor. This drug is given in combination with B lactam antibiotics to inhibit B lactamase, an enzyme produced by bacteria that destroys the antibiotics.
Sulbactam is an irreversible inhibitor of B lactamase, it binds to the enzyme and does not allow it to degrade the antibiotic.
Sulbactam is able to inhibit the most common forms of B lactamase but is not able to interact with the Amp cephalosporinase. Thus, it confers little protection against bacteria such as Pseudomonas aeruginosa, Citrobacter, Enterobacter, and Serratia, which often express this gene.