TABLE 1.

MICs for bla_IMP-4-positive isolates of Acinetobacter spp.

Isolate type and lab no.	Sample	DNA group	Date isolated (mo/yr)	β-Lactamase pI(s)	MIC (μg/ml)a
					IMP	MEM	ATM	PIP	TZP	CTX	SUL
Isolates from which blaIMP-4 was sequenced
116665	Blood	2	10/94	5.4	0.5	0.25	16	>128	32	>128	16
127091	Blood	2	9/96	7.6, 8.0b	16	16	64	>128	64	>128	4
74510	Wound	13TU	5/95	5.7, 7.6, 8.0b	>32	>32	32	>128	32	>128	16
104680	Blood	3	8/98	5.7, 7.6, 8.0b	8	16	32	>128	64	>128	1
Collection of 23 blaIMP-4 positive isolates
MIC range					0.25–16	0.25–16	2–64	64–256	4–64	32–256	1–64
MIC50c					4	8	32	256	32	128	2
MIC90d					16	16	64	256	64	256	16

^aATM, aztreonam; CTX, cefotaxime; IMP, imipenem; MEM, meropenem; PIP, piperacillin; SUL, sulbactam; TZP, piperacillin-tazobactam (tazobactam at 4 μg/ml). 

^bEnzymes with pIs of 8.0 ceased to be detectable if the gel was overlaid with 3 mM EDTA for 10 min before addition of nitrocefin. 

^cMIC₅₀, MIC at which 50% of isolates are inhibited. 

^dMIC₉₀, MIC at which 90% of isolates are inhibited.