TABLE 1.

In vitro susceptibilities of strains used in hollow-fiber studies

Strain	β-Lactamase(s)	Regimensa	MIC (μg/ml)
			Ceftazidime	Avibactam	Ceftazidime + 4 μg/ml avibactam	Ceftazidime-avibactam at 4:1
E. cloacae 293HT96	Stably derepressed AmpC	1, 2, 3	>128	>32	4	8:2
K. pneumoniae Tunisie K4	CTX-M-15, TEM-1b, OXA-1b	1, 2	>128	>32	1	4:1
K. pneumoniae 283KB5	SHV-11, AmpC	1, 2	>128	>32	0.5	NTc
K. pneumoniae 283CF5	SHV-5	1, 2	64	>32	2	NT
K. pneumoniae 181	SHV-5, TEM-10	1, 2	>128	>32	2	8:2
K. pneumoniae 236	SHV-5, TEM-10	1, 2	>128	>32	2	1:0.25
K. pneumoniae 5761	KPC-3	1, 3	>128	>32	4	8:2
Citrobacter freundii 261GR3	AmpC, TEM-1b	1, 2	>128	>32	≤0.125	2:0.5

^aDosing regimens for which this organism was used (see the text for further details).

^bβ-Lactamase does not hydrolyze ceftazidime to any great extent.

^cNT, not tested.