TABLE 1.

MIC of β-lactams against E. coli TOP10 isogenic strains producing various AmpC β-lactamases

AmpC β-lactamase	MIC (μg/ml)a
	CAZ	CAZ-AVI	AMX	AMC	PIP	ETP	MEM	CF	MA	FOX	CTX	ATM	FEP
Noneb	0.25	0.25	2	2	2	≤0.06	≤0.06	8	1	4	0.06	0.25	0.12
AmpCcloacae	64	0.25	>256	>256	128	0.25	≤0.06	>256	256	128	64	32	1
AmpCcloacae N346Y	128	16	>256	>256	16	≤0.06	≤0.06	128	128	16	32	32	0.5
PDC-5	16	0.5	>256	>256	256	≤0.06	≤0.06	>256	256	128	32	16	0.5
PDC-5 N346Y	8	4	64	32	4	0.12	≤0.06	128	16	128	4	1	0.25
DHA-1	256	0.25	>256	>256	256	≤0.06	≤0.06	256	128	16	16	16	0.12
DHA-1 N346Y	64	16	128	128	8	≤0.06	≤0.06	16	4	8	2	16	0.12
FOX-3	256	2	128	128	8	≤0.06	≤0.06	>256	256	256	16	8	0.5
FOX-3 I346Y	16	1	32	32	1	≤0.06	≤0.06	32	1	8	0.25	0.5	0.12

^aCAZ, ceftazidime; CAZ-AVI, ceftazidime combined with avibactam (4 μg/ml); AMX, amoxicillin; AMC, amoxicillin combined with clavulanate (2 μg/ml); PIP, piperacillin; ETP, ertapenem; MEM, meropenem; CF, cephalothin; MA, cefamandole; FOX, cefoxitin; CTX, cefotaxime; ATM, aztreonam; FEP, cefepime.

^bNone, control pTRC-99k vector without any ampC-encoding gene.