Table.
Simplified functional classification of main groups of β lactamases, as proposed by Bush et al12
| Group | Molecular type | Preferred substrate | Representative enzyme (bacterium) |
|---|---|---|---|
| 1 | C | ceph | AmpC (Enterobacter spp etc) |
| 2a | A | pen | Penicillinase (Staphylococcus aureus) |
| 2b | A | pen, ceph | TEM-1 (Escherichia coli), SHV-1 (Klebsiella spp) |
| 2be/r | A | pen, ceph* | TEM 364, SHV 212 (enterobacteriaceae) |
| 2c | A | pen | PSE-1 (pseudomonas) |
| 2d | D | pen | OXA-111 (pseudomonas/enterobacteriaceae) |
| 2e† | A | ceph | Inducible chromosomal enzymes from proteus |
| 2f | A | pen, ceph, and carbapenems | SME-I (serratia) |
| 3 | B‡ | pen, ceph, carbapenems | IMP-I (pseudomonas) |
| 4 | — | pen | Pencillinase (Pseudomonas cepacia) |
*
Includes third generation cephalosporins, such as ceftazidime; some are not inhibited by clavulanic acid.
†
Inhibited by clavulanic acid.
‡
Metallo-β lactamase, which requires zinc for activity.