TABLE 3.

MICs and enzymatic kinetic parameters for the clinical E. coli isolates

Clinical isolate	pI	MIC (μg/ml)				Penicillin G		Residual activity (%)
		Amoxicillin		Piperacillin
		Alone	With Caa	Alone	With Tazb	Km (μM)	Sp act (mU/mg)
AP1	5.4	2,048	32	64	1	25	335	9.5
AP2	5.4	>4,096	256	1,024	32	25	1,786	9.3
AP3	5.4	2,048	32	64	1	27	586	10
AP4	7.4	4,096	128	256	32	5	61	NDc
AP5	5.4	2,048	512	32	4	7	144	56
AP6	5.2	4,096	2,048	128	4	138	3,200	46.5
AP7	5.2	1,024	256	8	1	216	925	33
AP8	5.2	2,048	1,024	32	2	232	660	32.5

^aCa, clavulanic acid at 2 μg/ml. 

^bTaz, tazobactam at 4 μg/ml. 

^cND, not determined (the enzyme was unstable).