TABLE 2.

MICs of selected β-lactams for host strain E. coli XL-1 Blue MRF′ [pBC SK(+)] and clones containing the recombinant phagemids pARL98-1 and pARL98-2

Antibiotic	MIC (μg/ml) for:
	pBC SK(+)	pARL98-1 (blaB2)	pARL98-2 (blaB3)
Imipenem	0.125	0.125	0.25
Meropenem	0.012	0.012	0.016
Ampicillin	4	16	>256
Piperacillin	1	1	2
Aztreonam	0.25	0.25	0.25
Cefoxitin	16	16	16
Cefpirome	0.125	0.125	0.125
Ceftazidime	0.25	0.25	0.5