TABLE 4.

Binding of carbapenems to PBPs of S. aureus, E. coli, and P. aeruginosa

Organism	PBP	Concn (μg/ml) required to inhibit binding of [14C]benzylpenicillin by 50% or MIC (μg/ml)a
		Imipenem	Meropenem	Biapenem	CL 188,624	CL 190,294	CL 191,121
S. aureus 29213	1	0.02	0.03	0.01	0.01	0.03	0.006
	2	0.10	0.18	0.06	0.1	0.2	0.04
	3	0.18	0.80	0.05	5.0	20b	0.06
	4	0.06	0.08	0.06	0.1	0.15	0.02
	MICa	≤0.06	≤0.06	≤0.06	≤0.06	≤0.06	≤0.06
E. coli 25922	1a	0.07	0.2	1.0	3.0	6.0	0.5
	1b	0.10	0.2	1.0	3.0	6.0	0.5
	2	0.05	0.02	0.003	0.03	0.03	0.05
	3	2.0	0.4	2.5	0.5	0.4	8.0
	4	0.07	0.02	0.01	0.05	0.06	<0.1
	5/6	3.9	17	90	50	40	>10
	MIC	0.12	<0.06	<0.06	<0.06	<0.06	<0.06
P. aeruginosa 27853	1b	0.37	0.5	0.06	0.33	0.07	0.04
	1c	0.29	0.5	0.40	0.40	0.30	0.20
	2	0.43	0.03	0.18	0.04	0.10	0.05
	3	0.42	0.04	0.30	0.40	0.04	0.2
	4	10	0.03	0.03	0.6	0.07	<0.1
	5/6	20	>100	90	>10	>10	>10
	MIC	2.0	0.5	0.50	32	32	16
P. aeruginosa 27853a	MIC	32	8	8	32	32	16
P. aeruginosa GC1543d	MIC	16	16	16	64	64	16

^aNote that MICs were determined by the standard broth microdilution methodology (21). 

^bEstimate. 

^cIsogenic OprD2-deficient mutant from P. aeruginosa 27853 selected with imipenem. 

^dOprD2-deficient isolate (isolate B from Quinn et al. [24]).