Types of beta lactamase enzyme

Bacteria also can destroy beta-lactam antibiotics enzymatically.
b-Lactamases are capable of inactivating certain of these antibiotics and may be present in large quantities
Different microorganisms elaborate a number of distinct beta-lactamases, although most bacteria produce only one form of the enzyme. The substrate specificities of some of these enzymes are relatively narrow, and these often are described as either penicillinases or cephalosporinases.
Other "extended spectrum" enzymes are less discriminant and can hydrolyze a variety of b-lactam antibiotics.
b-Lactamases are grouped into four classes: A through D.
Class A b-lactamases include the extended-spectrum b-lactamases (ESBLs) and degrade penicillins, some cephalosporins, and, in some instances, carbapenems
Class A and D enzymes are inhibited by the commercially available b-lactamase inhibitors, such as clavulanate and tazobactam
Class B b-lactamases are Zn2+-dependent enzymes that destroy all b-lactams except aztreonam,
class C b-lactamases are active against cephalosporins
Class D includes cloxacillin-degrading enzymes (Bush, 2001)