TABLE 3.

MICs for E. coli RB791-containing CTX-M-14 mutants, the wild type, and the empty vector control

Plasmid or WT or mutant β-lactamase	MIC (μg/ml)a
	AMP	CEF	CTX	CAZ
pTP123	<4	8	<0.05	0.19
CTX-M-14	250	938	4	0.5
A77V	250	468	3	0.5
P167S	125	312	2	3
D240G	63	312	2	1
A77V/P167S	375	468	7	5
A77V/D240G	188	468	6	3

^aAMP, ampicillin; CEF, cephalothin; CTX, cefotaxime; CAZ, ceftazidime.