Which of the following compounds is a beta-lactamase inhibitor?

Tazobactam is identified as a beta-lactamase inhibitor, which is crucial for enhancing the efficacy of certain antibiotics, particularly beta-lactams like penicillins. Beta-lactamases are enzymes produced by some bacteria that can break down beta-lactam antibiotics, rendering them ineffective. Tazobactam works by binding to these enzymes and inhibiting their activity, thereby protecting beta-lactam antibiotics from degradation and allowing them to exert their antibacterial effects.

In contrast, the other compounds listed do not function as beta-lactamase inhibitors. Cephalexin is a type of cephalosporin antibiotic, designed to combat bacterial infections but does not inhibit beta-lactamases. Ciprofloxacin is a fluoroquinolone antibiotic that works through a different mechanism, targeting DNA gyrase and topoisomerase IV to inhibit bacterial DNA replication. Vancomycin is a glycopeptide antibiotic used primarily against gram-positive bacteria and does not have any activity against beta-lactamases. Therefore, Tazobactam stands out as the appropriate choice due to its specific role in inhibiting beta-lactamase enzymes.