. 2014 Apr 22;5(2):e01068-14. doi: 10.1128/mBio.01068-14

TABLE 1 .

Impact of MexY mutations on antimicrobial susceptibility of P. aeruginosa^a

Strain	Plasmid	MexY mutation	MIC (μg/ml)^b
Strain	Plasmid	MexY mutation	STR	PAR	NEO	AMI	ERY	SPC	CAM	NOR^c	CEF^d
K767	None	WT	32	256	32	2	512	512	64	ND^e	ND
K3315	None	None	2	8	4	0.5	64	64	64	ND	ND
K3315	pRK415	None	2	16	4	0.5	64	64	32	0.5	1
K3315	pCL10	WT	8	64	8	1	512	512	32	2	4
K3315	pCL14	G216D	2	16	ND	ND	64	64	32	0.5	1
K3315	pCL13	R184H	4	32	ND	ND	256	256	32	ND	ND
K3315	pCL11	S16F	4	32	ND	ND	256	256	32	ND	ND
K3315	pCL17	A960T	4	16	ND	ND	256	256	32	ND	ND
K3315	pCL15	V339M	4	16	8^f	1	512	256	32	2	1
K3315	pCL12	R166C	4	32	ND	ND	256	512	32	2	4
K3315	pCL16	P562S	8	32	ND	ND	256	512	32	ND	ND
K3315	pCL19	D133A	4	16	4	0.5	256	1024	32	ND	ND
K3315	pCL20	D133S	4	16	4	0.5	256	1024	32	ND	ND
K3315	pCL18	K79A	8	128	8^g	1	512	1024	32	ND	ND
K3315	pCL21	Y613A	4	16	4	0.5	512	256	32	2	2

^{^a}

The antimicrobial susceptibility of P. aeruginosa ΔmexY strain K3315 carrying the indicated plasmids expressing wild-type (WT) MexY or MexY derivatives with the indicated amino acid substitutions is reported. Results for WT strain K767 and plasmid-free K3315 are provided for comparison purposes.

^{^b}

MIC values lower than that measured for pCL10-carrying K3315 expressing WT MexY are bolded. MIC values higher than that measured for pCL10-carrying K3315 are italicized. STR, streptomycin; PAR, paromomycin; NEO, neomycin; AMI, amikacin; ERY, erythromycin; SPC, spectinomycin; CAM, chloramphenicol; NOR, norfloxacin; CEF, cefepime.

^{^c}

NOR MICs were determined in the presence of 8 µg/ml chloramphenicol. The NOR MIC for all strains in the absence of chloramphenicol was 0.5 µg/ml.

^{^d}

CEF MICs were determined in the presence of 8 µg/ml chloramphenicol. The CEF MIC determined in the absence of chloramphenicol was 1 (for pRK415 control and MexY_G216D) or 2 (for MexY_WT and its V339M, R166C, and Y613A variants) μg/ml.

^{^e}

ND, not determined.

^{^f}

At half the NEO MIC (4 µg/ml), MexY_V339M-expressing K3315 grew reproducibly slower than K3315 expressing MexY_WT (data not shown), indicating that the V339M mutation compromises neomycin resistance.

^{^g}

At half the NEO MIC (4 µg/ml), MexY_K79A-expressing K3315 grew reproducibly faster than K3315 expressing MexY_WT (data not shown), indicating that the K79A mutation enhances neomycin resistance.