Table 2.

Killing activities of doripenem and colistin alone or in combination against 23 KPC-K. pneumoniae isolates

Isolate no.	MIC (μg/ml)a		KPC expressionb	ompK36 genotype	Level of killing (log10 CFU/ml) at (h):
	Dori	Col			Dori				Col				Dori + Col
					4	8	12	24	4	8	12	24	4	8	12	24
83	32	128	4.88	Wild type	−2.30	−2.32	−0.14	3.48	−0.83	−0.30	−1.09	−2.49	−1.35	−2.41	−2.83	−4.27
25	16	16	4.10	Wild type	−0.90	−1.59	−2.14	−3.17	−0.59	−0.91	−1.01	1.85	−1.19	−1.95	−2.65	−3.47
216	4	8	5.02	Wild type	−2.57	−1.13	2.68	3.72	0.27	1.79	3.51	3.91	−2.91	−3.34	−3.14	0.72
347	4	0.125	5.04	Wild type	−3.14	−1.00	2.21	3.90	−3.81	−2.08	−3.16	2.07	−3.41	−4.27	−6.05	−4.57
383	8	0.125	4.11	Wild type	2.17	3.48	3.63	3.90	−4.37	−3.66	−1.61	3.47	−4.30	−3.51	−6.08	−6.08
41	4	64	5.02	Del aa84-87NNTE	−3.71	−1.36	1.68	3.68	−2.56	−4.34	−2.76	3.60	−3.77	−6.03	−6.03	−6.03
44	32	4	4.8	A11V	−2.47	−0.25	2.79	3.64	−0.48	−0.48	−0.38	−1.36	−1.38	−1.97	−2.42	−2.75
539	64	0.25	4.3	Frameshift (ins nt382 G)	2.47	3.42	3.78	3.80	−3.00	−1.47	−2.29	−1.10	−3.80	−3.62	−3.42	−4.69
175	64	2	4.75	Ins aa134-135 GD	3.19	3.95	4.11	4.106	−0.82	−1.08	−1.32	−0.71	−2.27	0.10	−0.02	−1.88
89	128	64	5.02	Ins aa134-135 GD	2.48	3.22	3.19	3.19	−1.14	−1.57	−1.44	−2.29	−2.02	−3.55	−3.08	−4.40
168	128	32	3.26	Ins aa134-135 GD	2.71	3.26	3.12	3.51	−0.35	−0.72	−0.26	3.81	−2.15	−3.25	−1.32	−0.77
115	32	0.125	4.30	Ins aa134-135 GD	2.40	3.66	4.42	3.84	−4.53	−3.92	−2.85	2.20	−3.70	−3.55	−2.00	3.28
184	32	8	3.88	Ins aa134-135 GD	2.63	3.57	3.81	3.83	0.27	0.27	1.95	3.96	−0.84	−1.02	0.74	3.80
155	32	2	4.60	Ins aa134-135 GD	2.47	3.43	3.80	3.70	−6.10	−2.08	−1.36	1.68	−4.10	−2.39	−2.01	2.77
484	128	0.25	4.75	Ins aa134-135 GD	2.24	3.51	3.89	3.95	−4.33	−2.09	−1.76	1.48	−3.64	−3.97	−2.58	2.15
436	32	0.125	3.67	Ins aa134-135 GD	2.30	3.47	3.58	3.82	−4.03	−2.44	−0.83	3.79	−4.00	−2.59	−0.85	3.78
178	256	16	4.89	IS5 ins and promoter del	−1.63	0.61	3.43	3.79	−0.48	−0.48	−0.37	−1.11	−0.27	−0.24	−0.33	−1.23
220	256	16	5.15	IS5 ins and promoter del	−2.07	0.85	2.66	3.27	−0.81	−0.85	−1.44	−0.39	−0.67	−1.13	−2.38	−2.62
94	128	4	4.457	IS5	1.92	3.65	3.77	3.78	−0.66	−0.81	−1.14	−2.29	−1.07	−1.73	−2.73	−3.96
121	256	4	5.34	IS5	−0.77	−1.29	−2.21	−1.32	−0.82	−0.99	−2.05	−1.46	−1.05	−1.32	−2.35	−3.24
1	128	8	4.80	IS5	−0.15	3.08	3.64	3.85	2.22	3.56	3.80	3.85	1.48	3.30	3.70	3.83
404	64	2	5.02	IS5	1.84	3.46	3.57	1.48	−1.32	−0.10	−1.72	−1.42	−1.78	−3.11	−3.36	−3.99
584	32	32	5.23	IS5	1.60	1.38	2.08	3.67	1.97	1.77	2.47	3.83	−1.59	−1.82	−1.11	3.60

^aDori, doripenem; Col, colistin.

^bExpression was determined by qRT-PCR, with normalization to the housekeeping gene rpoB and relative to expression by K. pneumoniae strain ATCC 13883 (29, 30). Experiments were performed in triplicate.