TABLE 2.

In vitro potencies of meropenem alone and combined with QPX7728 at 4 μg/ml and 8 μg/ml against 135 carbapenem-resistant Acinetobacter strains according to carbapenemase present

CRB	n	Drug	No. of strains at a meropenem MIC (μg/ml) of:												GMa MIC	MIC50 (μg/ml)	MIC90 (μg/ml)	%Sb
			≤0.06	0.125	0.25	0.5	1	2	4	8	16	32	64	>64
All	135	MER							8	2	10	21	59	35	51.1	64	65	7.4
		QPX 4 μg/ml	4	2	5	12	22	38	28	18	6				1.9	2	8	95.6
		QPX 8 μg/ml	11	3	13	17	22	34	15	16	4				1.1	2	8	97.0
OXA-23	71	MER									3	14	50	4	54.7	64	64	0.0
		QPX 4 μg/ml			3	6	8	18	17	15	4				2.7	4	8	94.4
		QPX 8 μg/ml	4		6	6	11	16	10	14	4				1.8	2	8	94.4
OXA-72	16	MER											4	12	107.6	65	65	0.0
		QPX 4 μg/ml	1	1		3	4	3	2	2					1.1	1	8	100
		QPX 8 μg/ml	1	1	2	6	1	4	1						0.6	0.5	2	100
OXA-24	16	MER											2	14	117.4	65	65	0.0
		QPX 4 μg/ml	1		2	2	3	6	2						1.0	1	4	100
		QPX 8 μg/ml	2	2	3	1	5	3	0						0.4	0.5	2	100
OXA-58	9	MER							3		4	2			11.8	16	NDc	33.3
		QPX 4 μg/ml	1	1		1	2	3		1					0.8	1	ND	100
		QPX 8 μg/ml	1		1	1	1	3	2						0.9	2	ND	100
OXA-239	4	MER										3	1		38.1	32	ND	0.0
		QPX 4 μg/ml					2	2							1.4	1	ND	100
		QPX 8 μg/ml			1	1	2								0.6	0.5	ND	100
KPC	1	MER												1	>64	ND	ND	0.0
		QPX 4 μg/ml	1												≤0.06	ND	ND	100
		QPX 8 μg/ml	1												≤0.06	ND	ND	100
NDM	5	MER												5	128.0	65	ND	0.0
		QPX 4 μg/ml						1	2		2				6.1	4	ND	60
		QPX 8 μg/ml	2					1		2					0.7	2	ND	100
None	13	MER							5	2	3	2	1	0	10.4	8	32	53.8
		QPX 4 μg/ml					3	5	5						2.2	2	4	100
		QPX 8 μg/ml				2	2	7	2						1.6	2	4	100

^aGM, geometric mean. For calculations, a MIC of >64 μg/ml was assumed to be 128 μg/ml.

^b%S (susceptible) at meropenem PK-PD breakpoint of 8 μg/ml.

^cND, not done.