Influence of PhoPQ and PmrAB two component system alternations on colistin resistance from non-mcr colistin resistant clinical E. Coli strains

Table 3 Colistin MICs and gene expression levels in different E. coli TSAREC03 mutants

Strain	Chromosomal phoP status^{a, b}	Chromosomal pmrB status	Episomal pmrB status	Relative expression level (mean ± SD)					Colistin MIC (µg/mL)
Strain	Chromosomal phoP status^{a, b}	Chromosomal pmrB status	Episomal pmrB status	phoP	pmrD	pmrA	pmrB	pmrK	Colistin MIC (µg/mL)
MG1655	WT	WT	None	1	1	1	1	1	0.5
TSAREC03	g252a (premature termination)	g3c, t41c, c532t, c704a (M1I, L14P,P178S,T235N)	None	0.17 ± 0.08	0.59 ± 0.24	116.79 ± 21.12	38.18 ± 10.46	146.32 ± 98.16	8
TSAREC03_ΔphoP^Δ84–224	Deleted	g3c, t41c, c532t, c704a (M1I, L14P,P178S,T235N)	None	ND	ND	ND	ND	ND	8
TSAREC03 WT-phoP revertant	WT	g3c, t41c, c532t, c704a (M1I, L14P,P178S,T235N)	None	0.56 ± 0.41	1.44 ± 0.54	106.04 ± 41.17	32.53 ± 17.84	112.03 ± 61.87	8
TSAREC03_ΔpmrB^{g3c, t41c, c532t, c704a}	g252a (premature termination)	Deleted	None	ND	ND	4.66 ± 0.56	< 0.01	2.74 ± 0.71	0.25
TSAREC03 _ΔpmrB^{g3c, t41c, c532t, c704a} (pCRII-TOPOpmrB^{g3c, t41c, c532t, c704a})	g252a (premature termination)	Deleted	g3c, t41c, c532t, c704a (M1I, L14P,P178S,T235N)	ND	ND	157.00 ± 43.61	66.52 ± 44.80	251.70 ± 133.80	8

MIC, minimum inhibitory concentration
^aThe one-letter code was used for amino acid designation
^bWT, wild type, indicating that the sequence was identical to that of the colistin-susceptible E.coli strains MG1655 or ESC01 to ECS08

ISSN: 1471-2180