A beta-lactamase inhibitor is a molecule used in conjunction with a beta-lactam antibiotic to extend its spectrum of activity.
Although beta-lactamase inhibitors have little antibiotic activity of their own, they instead inhibit the activity of beta-lactamases, a family of enzymes that break the beta-lactam ring that allows penicillin-like antibiotics to work, thereby conferring bacterial resistance.
Some bacteria can produce extended spectrum beta-lactamases, or ESBLs, making the infection more difficult to treat and conferring additional resistance to penicillins, cephalosporins, and carbapenems.
Commonly used agents 
Beta-lactamase producing bacteria 
Bacteria that can produce beta-lactamases include, but are not limited to:
- ^ "Beta-Lactamase Inhibitors". Department of Nursing of the Fort Hays State University College of Health and Life Sciences. October 2000. Archived from the original on 2007-09-27. Retrieved 2007-08-17.
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