TABLE 1.

MICs (μg·ml⁻¹) of cefalexin against E. coli isolates and mutant derivatives^b

Isolate or mutant	Cefalexin MIC (μg·ml−1)
PSA	16
PSA (M)a	32
ATCC 25922	16
ATCC 25922 (M)	32
EC17	8
EC17 (M)	32
ATCC 25922 ompF	32
ATCC 25922 rseA	64
ATCC 25922 gmhB	64
Farm 1	64
Farm 2	64
UTI-1	32
UTI-2	32

^aM, mutants selected for growth on cefalexin.

^bShaded values represent resistant based on CLSI breakpoints (24); otherwise, nonshaded values represent susceptible.