TABLE 1.

Isoelectric points and susceptibilities of AmpC-producing isolates

Isolate	pIa	MICb (μg/μl)
		AMP	FOX	FOX-Ro(4)	CPD	CPD-Cl(4)	CRO	CRO-Cl(2)	CTX	CAZ	AZT	CEF	IMI
E. coli
M477	9.1	256	32	8	128	128	16	16	8	128	16	4	0.13
M491	9.1	512	64	16	128	128	4	4	8	32	16	0.13	0.13
M483	9.1	512	32	8	512	256	16	16	16	64	16	0.5	0.13
M540	9.0, 5.4	4,096	128	32	128	128	2	1	4	4	16	0.13	0.06
M545B	9.0	512	64	16	128	64	1	1	4	4	16	0.06	0.06
M563c	9.1	265	32	2	128	64	1	0.5	2	4	8	0.03	0.13
M656	9.1	64	8	2	8	4	0.13	0.13	0.5	0.5	1	0.06	0.13
M683	9.0	64	8	2	8	8	0.13	0.06	0.5	0.5	1	0.02	0.06
M752	7.2, 5.6	>4,096	64	32	128	128	2	2	8	32	1	0.06	0.13
M804	9.0	256	32	4	128	64	1	0.5	2	2	2	0.03	0.13
M809	9.0	512	128	4	512	512	32	32	16	32	16	0.13	0.13
K. pneumoniae
M484	7.2, 5.6	>4,096	1,024	1,024	2,048	2,048	64	32	32	256	8	4	1.0
M621	7.2, 5.6, 7.8	>4,096	64	64	128	128	8	4	16	64	16	0.25	0.13
M625B	7.2, 5.6, 7.8	>4,096	128	64	256	128	8	4	8	64	32	0.5	0.13
M846	7.2, 5.6	>4,096	64	64	256	256	8	8	16	64	4	0.5	0.25
P. mirabilisM910	9.0	128	16	2	256	256	2	2	4	1	0.25	0.13	4.0

^aThe first isoelectric points correspond to those for the cloxacillin-inhibited band (AmpC); additional pIs correspond to those for clavulanic acid-inhibited bands. 

^bAMP, ampicillin; FOX, cefoxitin; FOX-Ro(4), cefoxitin plus 4 μg of Ro 48-1220 per ml; CPD, cefpodoxime; CPD-Cl(4), cefpodoxime plus 4 μg of clavulanic acid per ml; CRO, ceftriaxone; CRO-Cl(2), ceftriaxone plus 2 μg clavulanic acid per ml; CTX, cefotaxime; CAZ, ceftazidime; AZT, aztreonam; CEF, cefepime; IMI, imipenem. 

^cResistance was transferred for the underlined isolates.