TABLE 1.

Susceptibility to and accumulation of fluoroquinolones in V. cholerae and E. coli strains

Strain	MIC (μg/ml)a		Accumulation of NOR (μg mg−1 cell dry wt)b
	NOR	CIP	Before addition of CCCP	After addition of CCCP
V. cholerae strains
Wild type (N16961)	0.0156	0.0039	0.031 ± 0.0012	0.394 ± 0.022
NorM-KO	0.001	0.0004	0.331 ± 0.0019	0.415 ± 0.0025
E. coli strainsc
TG1ΔacrAB harboring pBADHisC (control)	0.016	0.004	0.367 ± 0.009	0.428 ± 0.012
norM wt/pBADHisC*	1	0.125	0.191 ± 0.012	0.436 ± 0.011
norM G187R/pBADHisC*	0.063	0.032	0.298 ± 0.009	0.432 ± 0.009
norM E190K/pBADHisC*	0.016	0.004	0.386 ± 0.011	0.425 ± 0.012
norM G192V/pBADHisC*	0.5	0.125	0.188 ± 0.008	0.433 ± 0.008

^aAll experiments were carried out thrice with the same results.

^bData are means ± standard deviations for three independent determinations.

^c*, norM wt/pBADHisC refers to the wild-type norM gene cloned into pBADHisC, norM G187R/pBAD HisC refers to the mutant norM gene encoding the G187R mutation cloned into pBADHisC, and so on.