Sulbactam (CP45899) is a semi-synthetic beta-lactamase inhibitor. The beta-lactam ring of sulbactam irreversibly binds to beta-lactamase at or near its active site, thereby blocking enzyme activity and preventing metabolism of other beta-lactam antibiotics by the enzyme. Combining this agent with a beta-lactamase susceptible antibiotic, such as penicillins or a cephalosporin, to treat infections caused by beta-lactamase producing organisms, results in a decreased turnover rate of the beta-lactamase sensitive antibiotic and enhances its antibacterial activity.