TABLE 3.

Amino acid changes in PmrA/PmrB^a and gene expression levels of colistin-resistant E. coli strains

Strain	Substitution(s) inb:		Relative expression level (mean ± SD)c
	PmrA	PmrB	pmrD	pmrK	pmrC
TSAREC01	R81H		1.20 ± 0.39	115.41 ± 44.95	143.12 ± 50.09
TSAREC02		G206R, Y222H	0.78 ± 0.35	103.14 ± 38.34	168.64 ± 63.00
TSAREC03		M11, L14P, P178S, T235N	0.53 ± 0.22	123.54 ± 49.64	720.94 ± 343.66
TSAREC04	R81H		0.47 ± 0.15	61.35 ± 22.42	101.36 ± 24.14
TSAREC05		P94L	0.22 ± 0.06	64.79 ± 36.92	148.06 ± 89.43
TSAREC06		G19E	0.44 ± 0.17	45.01 ± 7.15	103.35 ± 41.94
TSAREC07		P94L	0.63 ± 0.21	99.80 ± 40.17	295.63 ± 117.03
TSAREC08		L194P	0.38 ± 0.20	94.36 ± 41.61	201.4 ± 67.89
TSAREC10		L98R	0.52 ± 0.12	54.44 ± 16.91	216.15 ± 47.24
TSAREC37		L27R	0.65 ± 0.14	25.19 ± 8.06	122.06 ± 52.40
TSAREC41	R81H		0.36 ± 0.07	59.50 ± 18.18	117.67 ± 39.61

^aAmino acid substitutions found only in colistin-resistant E. coli isolates after alignment with 8 clinical colistin susceptible E. coli strains (ECS01 to ECS08) and MG1655.

^bThe one-letter designations for amino acids are used.

^cExpression levels of pmrD, pmrC, and pmrK genes (presented as fold change) were normalized against the value for MG1655. Values are means and standard deviations from four independent experiments.