Table 1.

MICs of β-lactams.

MICs (μg/ml)
Antibiotics	E. coli TOP10 (pPAN-1)	E. coli HB4 (pPAN-1)	E. coli TOP10	E. coli HB4*	E. coli TOP10 (pSPM-1)
Amoxicillin	128	>128	2	16	>128
Amoxicillin + clavulanic acid a	128	>128	1	16	>128
Piperacillin	32	64	1	8	64
Cephalothin	128	>128	4	128	>128
Cefoxitin	128	>128	2	64	>128
Ceftazidime	32	64	0.125	1	>128
Cefotaxime	4	8	0.06	0.5	64
Cefepime	0.5	2	0.125	0.5	16
Aztreonam	0.06	0.38	0.06	0.38	0.06
Imipenem	0.5	0.5	0.06	0.06	0.5
Meropenem	0.25	4	0.06	0.25	0.5
Ertapenem	0.5	2	0.06	1	4

Light gray shaded MICs represent values of intermediate profile susceptibility, and boldened MIC values correspond to resistance according to the CLSI guidelines.

^aClavulanic acid was added at a fixed concentration of 2 μg/ml.

^*E. coli HB4 is a porin-deficient strain.