TABLE 3.

Susceptibilities to beta-lactams distributed by species and ESBL gene type^a

Species and ESBL type	No. of isolates	MIC50/MIC90 of beta-lactam (μg/ml)
		Piperacillin	Cephalothin	Ceftriaxone	Cefotaxime	Ceftazidime	Cefepime	Cefoxitin	Aztreonam	Imipenem
P. mirabilis
TEM+	127	>256/>256	>256/>256	4/8	8/16	4/16	4/16	4/8	0.5/2	1/2
P. stuartii
TEM+	22	>256/>256	>256/>256	4/32	8/16	32/>256	2/>32	2/128	4/16	1/2
K. pneumoniae
TEM+	32	>256/>256	>256/>256	4/32	4/32	>256/>256	2/8	2/16	32/>256	0.25/0.5
SHV+	104	>256/>256	>256/>256	8/32	8/32	>256/>256	2/16	2/16	>256/>256	0.25/0.5
TEM+ and SHV+	34	>256/>256	>256/>256	8/32	8/32	>256/>256	2/16	2/16	>256/>256	0.25/0.25
Non-TEM/non-SHV	18	>256/>256	>256/>256	8/>256	8/32	>256/>256	2/8	4/16	>256/>256	0.25/0.5
E. coli
TEM+	11	>256/>256	>256/>256	4/32	8/16	16/128	4/16	2/4	4/8	0.25/0.25
SHV+	28	>256/>256	>256/>256	4/32	4/32	32/>256	1/8	2/4	16/>256	0.25/0.25
E. aerogenes
TEM+	11	>256/>256	>256/>256	8/16	8/16	>256/>256	1/2	>256/>256	16/32	0.25/0.25
SHV+	14	>256/>256	>256/>256	16/64	16/32	>256/>256	2/16	>256/>256	64/>256	0.25/0.5

^aMICs were measured by the quantitative E-test assay. Values are not reported when fewer than 10 isolates were available.