Table 2. MICs of β-lactams for Escherichia coli strains isolated from cattle, transconjugants, and recipients^a.

	MIC (μg/mL) for E. coli strain:
Antimicrobial drug	GS528	CSH2 trGS528	GS554	CSH2 trGS554	CSH2
Piperacillin	>64	>64	>64	>64	<16
Cefotaxime	>128	>128	>128	>128	<0.5
Cefotaxime + CLAb	<0.12	<0.12	32	32	<0.12
Ceftazidime	2	4	32	32	<0.5
Ceftazidime + CLA	<0.12	<0.12	16	32	<0.12
Aztreonam	>64	64	>64	64	<0.5
Ceftriaxone	>64	>64	>64	>64	<0.5
Cefpodoxime	>64	>64	>64	>64	<0.5
Cefepime	>32	>32	>32	>32	<1
Cefotetan	<0.5	<0.5	>32	>32	<0.5
Cefmetazole	1	1	>16	>16	1
Cefoxitin	<2	<2	>32	>32	<2
Meropenem	<0.5	<0.5	8	4	<0.5
Ceftiofur	>1,024	>1,024	>1,024	>1,024	<0.25

^aE. coli CSH2 trGS528 and trGS554 were transconjugants of E. coli GS528 and GS554, respectively.
^bCLA, clavulanic acid at a fixed concentration of 4 μg/mL.