Table 1.

Classification of β-lactamase

Ambler molecular classification	Busch-Jacoby functional groups	Active binding site	Common enzymes
A	2a, 2b, 2be, 2br, 2c, 2e, 2f	Serine	TEM, SHV, KPC, CTX-M, GES
B	3	Metallo	VIM, NDM, IMP
C	1	Serine	AmpC, P99
D	2d, 2de, 2df	Serine	OXA

Italicized enzymes represent carbapenemase production