Table 1.

MIC profile of E. coli JM83 expressing the KPC-6 β-lactamase

Antimicrobial agent	MIC (μg/ml)
	Controla	KPC-6
Benzylpenicillin	16	2,048
Ampicillin	2	4,096
Ampicillin-clavulanic acidb	2	2,048
Ampicillin-tazobactamb	2	2,048
Ampicillin-sulbactamb	1	2,048
Ampicillin-sulbactamc	2	256
Sulbactam	32	256
Amoxicillind	4	>2,048
Amoxicillin-clavulanic acidc	4	32
Clavulanic acid	32	32
Oxacillin	256	16,384
Ticarcillin	4	8,192
Ticarcillin-clavulanic acidb	4	8,192
Piperacillin	2	512
Piperacillin-tazobactamb	2	512
Cephalothin	4	512
Cefuroxime	4	4,096
Ceftazidime	0.125	32
Cefotaxime	0.031	32
Ceftriaxone	0.031	16
Cefepime	0.016	8
Cefoxitin	2	8
Cefmetazole	1	4
Moxalactam	0.125	8
Aztreonam	0.031	256
Imipenem	0.125	4
Meropenem	0.031	2
Ertapenem	0.004	2
Doripenem	0.031	1

^aThe control strain was E. coli JM83 with the pHF016 vector.

^bClavulanic acid was used at a constant concentration of 2 μg/ml. Sulbactam and tazobactam were used at a constant concentration of 4 μg/ml.

^cA 2:1 ratio was maintained for the β-lactam and β-lactamase inhibitor (clavulanic acid or sulbactam).

^dIn Mueller-Hinton II broth, the maximum solubility of amoxicillin is 2,048 μg/ml.