TABLE 3.

In vivo efficacy of MK-826 and other agents against gram-negative organisms in a murine systemic infection model

Challenge strain	Com- pound	MICa (μg/ml)	ED50 (95% CL)b
E. cloacae MB2646c	MK-826	0.500	0.227 (ND)
	IPM	0.250	0.062 (0.024–0.161)
	FEP	4.000	0.235 (0.135–0.410)
	CTRX	≥256.000	30.400 (17.400–52.900)
E. coli MB2884	MK-826	0.008	0.022 (ND)
	IPM	0.125	0.172 (ND)
	FEP	0.031	0.013 (0.006–0.028)
	CAZ	0.125	0.062 (ND)
	CTRX	0.031	0.028 (ND)
K. pneumoniae MB2883	MK-826	≤0.016	0.057 (ND)
	IPM	0.125	6.080 (3.490–10.580)
	FEP	≤0.016	1.880 (1.080–3.280)
	CTRX	0.031	0.033 (0.015–0.072)
M. morganii MB2833	MK-826	0.008	0.034 (0.020–0.060)
	IPM	2.000	3.400 (1.950–5.920)
	FEP	0.016	0.074 (0.034–0.161)
	CAZ	0.125	0.318 (0.160–0.630)
	CTRX	0.008	≤0.018 (ND)
P. aeruginosa MB2835	MK-826	1.000	1.215 (0.698–2.116)
	IPM	1.000	0.455 (ND)
	FEP	8.000	≥9.100 (ND)
	CAZ	1.000	8.756 (3.997–19.180)
P. aeruginosa MB3286	MK-826	8.000	3.000 (1.060–8.470)
	IPM	2.000	0.142 (0.059–0.341)
	FEP	2.000	0.422 (0.170–1.010)
	CAZ	2.000	0.394 (0.151–1.030)
P. mirabilis MB3125	MK-826	0.031	0.034 (0.020–0.060)
	IPM	4.000	12.200 (6.980–21.200)
	FEP	0.031	0.071 (ND)
	CTRX	0.031	≤0.004 (ND)
S. marcescens MB3548	MK-826	0.500	0.121 (0.061–0.238)
	IPM	1.000	4.720 (2.150–10.340)
	FEP	0.500	0.535 (0.271–1.054)
	CTRX	0.500	0.469 (0.270–0.817)

^aMIC determined by procedures recommended by the National Committee for Clinical Laboratory Standards (14). 

^bThe ED₅₀ (calculated on day 7) that protects 50% of infected mice and the 95% confidence limit (95% CL) (both in milligrams per kilogram) are reported. ND, not defined. 

^cChallenge with test organisms (0.5 ml; i.p.) and treatment (0.5 ml; s.c.) begun immediately and 4 h after infection (total of 2 doses).