TABLE 1.

Antimicrobial susceptibilities, IEF of β-lactamases, and plasmid sizes of E. coli clinical isolates and their transconjugants

Strain	MIC (μg/ml)a							Isoelectric point(s)	Plasmid size(s) (kb)
	PIP	CEP	CFX	CTX	CAZ	ATM	IMP
Ec11	>256	32	8	16	16	8	<0.5	5.9	85, 63
Transconjugant	16	8	4	8	8	2	<0.5	5.9	63
Ec1	16	32	4	32	32	16	<0.5	5.4, 5.9	115, 102
Transconjugant	16	16	4	16	16	4	<0.5	5.9	102
Ec15	>256	32	4	32	32	8	<0.5	5.9	103
Transconjugant	>256	32	4	32	32	8	<0.5	5.9	103
Ec7	>256	16	8	32	16	4	<0.5	5.4, 5.9	130, 90
Transconjugant	>256	8	4	8	8	4	<0.5	5.4, 5.9	130
Ec8	>256	16	8	32	16	4	<0.5	5.4, 5.9	130
Transconjugant	>256	16	8	8	8	4	<0.5	5.4, 5.9	130
Ec101	128	16	16	8	8	2	<0.5	5.4, 5.9	103
Transconjugant	128	16	32	8	8	2	<0.5	5.4, 5.9	103
Ec106	>256	32	16	32	32	8	1	5.4, 5.9	91
Transconjugant	>256	16	16	32	16	8	<0.5	5.4, 5.9	91
Ec111	>256	64	16	32	64	16	<0.5	5.4, 5.9	135, 97
Transconjugant	>256	64	16	32	64	16	<0.5	5.4, 5.9	135, 97
Ec118	256	16	32	16	16	8	<0.5	5.4, 5.9	103, 84
Transconjugant	128	8	4	32	16	4	<0.5	5.4, 5.9	103, 84
Ec147	>256	64	32	128	128	64	<0.5	5.4, 5.9	63, 47
Transconjugant	128	2	4	8	8	2	<0.5	5.4, 5.9	47
Ec133	>256	>256	32	128	>256	>256	4	5.4, 8.2	77, 44
Transconjugant	128	32	8	4	16	16	<0.5	5.4	44
Ec145	256	1	16	2	1	1	<0.5	7.6	59, 41
Transconjugant	16	0.25	16	1	2	0.25	<0.5	7.6	41
Ec132	>256	32	>256	64	32	8	1	5.4, 7.6, 8.0	104, 56
Transconjugant	>256	16	4	8	16	4	<0.5	5.4, 7.6	104
Ec108	>256	32	>256	256	32	4	0.5	5.4, 8.0	77, 52
Transconjugant	>256	8	256	128	8	2	<0.5	5.4, 8.0	77, 52
Ec12	>256	64	256	32	64	8	2	5.4, 8.5	71, 50
Ec102	>256	128	64	256	128	64	2	5.4, >8.5	64

^aAbbreviations: PIP, piperacillin; CEP, cephalothin; CFX, cefoxitin; CTX, cefotaxime; CAZ, ceftazidime; ATM, aztreonam; IMP, imipenem.