TABLE 1.

MIC₉₀s^a of β-lactams for 10 selected S. typhimurium clinical isolates, E. coli DH10B harboring recombinant either plasmid pLPO-1 (bla_PSE-1) or pBR322 (bla_TEM-1), and an E. coli DH10B reference strain

Antibiotic	MIC90 (μg/ml)
	S. typhimurium isolates	E. coli DH10B (pLPO-1)	E. coli DH10B (pBR322)	E. coli DH10B
Amoxicillin	4,096	8,192	8,192	2
Amoxicillin + Clab	64	128	16	2
Amoxicillin + Tazc	32	128	32	2
Ticarcillin	>8,192	>8,192	>8,192	2
Ticarcillin + Cla	512	512	64	1
Ticarcillin + Taz	256	512	256	1
Piperacillin	512	512	512	1
Piperacillin + Cla	8	8	2	1
Piperacillin + Taz	8	8	8	1
Cephalothin	8	8	512	4
Cephalothin + Cla	4	4	16	4
Cephalothin + Taz	4	4	16	4
Cefamandole	2	2	128	2
Cefoxitin	4	8	8	8
Cefepime	<0.06	0.06	0.06	0.03
Ceftazidime	0.12	0.12	0.12	0.12
Cefotaxime	0.12	0.12	0.12	0.12
Ceftriaxone	0.06	0.06	0.06	0.03
Imipenem	0.12	0.12	0.06	0.06
Aztreonam	0.12	0.12	0.12	0.12

^aMIC₉₀, MIC at which 90% of isolates are inhibited. 

^bCla, clavulanic acid at a fixed concentration of 2 μg/ml. 

^cTaz, tazobactam at a fixed concentration of 4 μg/ml.