TABLE 1.

In vitro susceptibilities of an E. cloacae NOR-1 strain and its in vitro-obtained ceftazidime-resistant mutant to the β-lactams studied for various inoculum sizes

β-Lactam agent	MIC (μg/ml) with the indicated inoculum size (log10 CFU/ml):
	E. cloacae NOR-1				E. cloacae NOR-1 mutant
	4	5	6	7	4	5	6	7
Imipenem	8	16	512	>512	8	128	>512	>512
Meropenem	2	4	32	128	8	32	128	512
Cefepime	<0.03	<0.03	<0.03	4	1	1	16	128
Ceftazidime	0.03	1	2	128	256	512	>512	>512