TABLE 2.

Susceptibility levels of PSE-1 and TEM-1 Salmonella isolates to β-lactam antibiotics^a

Antibiotic	MIC (μg/ml)			No. resistantb
	Range	50%	90%
PSE-1 producers (n = 40)
Amoxicillin	≥2,048	>2,048	>2,048	40
Amoxicillin-clavulanic acidc	16–32	16	16	4
Piperacillin	256–>2,048	256	256	40
Piperacillin-tazobactamd	4–8	4	4	0
Cefuroxime	4–8	8	8	0
Cefoperazone	16–512	32	32	1
Cefotaxime	0.06–0.125	0.06	0.06	0
TEM-1 producers (n = 54)
Amoxicillin	1,024–>2,048	2,048	>2,048	54
Amoxicillin-clavulanic acid	8–32	16	16	1
Piperacillin	16–>2,048	128	256	32
Piperacillin-tazobactam	1–8	4	4	0
Cefuroxime	2–32	4	8	1
Cefoperazone	1–512	4	16	1
Cefotaxime	0.03–0.5	0.06	0.125	0

^aThe MICs for 2 of 96 strains (the PSE-1/TEM-2- and the OXA-4-producing strains) are not included in this table. 

^bAccording to the National Committee for Clinical Laboratory Standards breakpoints. 

^cAmoxicillin and clavulanic acid were associated in the ratio of 1/0.5. MIC values refer to the concentrations of amoxicillin. 

^dMIC values refer to the concentrations of piperacillin in the presence of a fixed amount of tazobactam (4 μg/ml).