Beta-lactamase: functional classification

Gaurab Karki — Wed, 10 Oct 2018 14:29:10 +0000

Beta-lactamase is an enzyme capable of hydrolyzing β-lactam antibiotics. β-lactamase degrade β-lactam antibiotics by opening the β-lactam ring. The microorganisms producing beta-lactamase enzyme become resistant β-lactam antibiotics.

Classification of β-lactamase enzyme on the basis of function:

These are class-C enzyme and are cephalosporinase which are not inhibited by clavulanic acid.
They are also resistant to cefamycin

Sub class:

i. Group 2b e (extended spectrum) β-lactamase:

These are ESBL capable of hydrolyzing penicillin even 3^rd and 4^th generation cephalosporin but are hydrolyzed by clavulanic acid.

ii. Group 2b r β-lactamase:

These includes inhibitor resistant β-lactamase. These may be resistant to sulbactum and clavulanic acid but are susceptible to inhibition by tazobactum.

iii. Group 2c β-lactamase:

These includes carbenicillinase. These enzymes hydrolyses carbenicillin more than Benzylpenicillin. These are class-A enzyme. They also show activity towards Oxacillin.

iv. Group 2d (extended spectrum) β-lactamase:

These are class-A or D enzyme and includes Cloxacillinase (oxacillinase). These enzymes hydrolyses cloxacillin more than Benzylpenicillin and also has activity against carbenicillin.

v. Group 2e β-lactamase:

These are class-A enzyme. These includes cephalosporinase. These are inhibited by clavulanic acid.

vi. Group 2f β-lactamase:

These are class-A enzyme. These includes carbapenimase. These are serine based enzyme which are also inhibited by clavulanic acid.

These includes class-B enzyme and are zinc based metalloenzyme. Eg. Carbapenimase
These are not inhibited by clavulanic acid.
They are chromosomal mediated enzymes