TABLE 1.

In vitro activity of several antimicrobial agents against ESBL-producing E. coli and K. pneumoniae isolates

Agent	E. coli				K. pneumoniae
	MIC range (μg/ml)	MIC50 (μg/ml)	MIC90 (μg/ml)	%Sa	MIC range (μg/ml)	MIC50 (μg/ml)	MIC90 (μg/ml)	%S
Cefotaxime	0.06->64	>64	>64	0	≤0.03->64	32	>64	0
Ceftazidime	0.5->64	16	>64	0	2->64	32	>64	0
Cefepime	≤0.03->64	8	>64	0	≤0.03->64	2	>64	0
Aztreonam	0.125->64	8	>64	0	0.125->64	8	>64	0
Cefpodoxime	0.5-512	128	256	0	≤0.25-512	64	256	0
Cefoxitin	1-256	4	16	76.5	1-256	4	8	94
Cefotetan	≤0.25-32	1	2	98	≤0.25-32	≤0.25	0.5	98.5
Amoxicillin-clavulanate (2:1)	2/1-128/64	8/4	32/16	69	4/2-128/64	16/8	32/16	40
Ticarcillin-clavulanate (2 μg/ml)	≤0.5->1,024	128	>1,024	13	≤0.5->1,024	256	>1,024	7
Piperacillin-tazobactam (4 μg/ml)	≤0.5->1,024	2	128	85	≤0.5->1,024	4	>1,024	74
Imipenem	≤0.06-1	0.125	0.25	100	≤0.06-0.5	0.125	0.25	100
Meropenem	≤0.06-0.25	≤0.06	≤0.06	100	≤0.06-0.125	≤0.06	≤0.06	100
Amikacin	0.5-128	2	16	93.5	0.5-64	1	16	91
Gentamicin	0.125->128	1	128	66	0.5->128	32	>128	33
Tobramycin	0.25->128	1	64	65	0.25-128	8	32	38.5
Ciprofloxacin	≤0.06->128	4	128	37.5	≤0.06-64	0.125	2	88.5
Co-trimoxazole	≤4.75/0.25->608/32	304/16	>608/32	25	≥4.75/0.25->608/32	19/1	608/32	40

^a%S, percent susceptibility.