TABLE 2.

Synergy of niclosamide with colistin against wild-type, efflux pump-deletion mutant and MDR/XDR colistin-susceptible P. aeruginosa^a

P. aeruginosa strain	MICNIC [MICcombo], μg/ml	MICCOL [MICcombo], μg/ml	FIC index	Absolute MICCOL,b μg/ml	Potentiation (fold)c
PAO1d	512 [1]	1 [0.125]	0.127	0.125	8
PAO200e	>512 [4]	0.5 [0.062]	0.125 < x < 0.133	0.125	4
PAO750f	2 [0.25]	0.5 [0.125]	0.375	0.062	8
PA095	256 [0.125]	0.25 [0.008]	0.032	0.004	64
PA259-96918	512 [1]	0.25 [0.125]	0.502	0.125	2
PA260-97103	512 [0.5]	0.5 [0.125]	0.251	0.125	4
PA262-101856	512 [0.5]	2 [0.125]	0.063	0.125	16
PA264-104354	512 [4]	2 [0.125]	0.070	0.5	4
100036	512 [0.125]	1 [0.125]	0.125	0.125	8
101885	512 [0.5]	1 [≤0.062]	0.001 < x ≤ 0.063	0.125	8
ATCC 27853d	>64 [4]	0.5 [0.25]	0.500 < x < 0.562	0.5	None

^aMIC_COL, colistin MIC; MIC_NIC, niclosamide MIC.

^bMIC of colistin in the presence of 1 μg/ml (3 μM) niclosamide.

^cDegree of colistin potentiation in the presence of 1 μg/ml (3 μM) niclosamide.

^dWild type.

^eThe MexAB-OprM deletion strain.

^fThe efflux-deficient strain that lacks five clinically relevant pumps (MexAB-OprM, MexCD-OprJ, MexEF-OprN, MexJK, and MexXY) and the outer membrane protein OpmH.