. 2013 Mar 14;4:53. doi: 10.3389/fmicb.2013.00053

Table 1.

Characterization of Salmonella Choleraesuis used in this study.

Strain no.	Susceptibility to nalidixic acid^a		Enrofloxacin-accumulation		mRNA expression		Mutations
	Category^b	MIC (mg/L)^b	Category^c	(ng/10⁵cfu)^c	acrA^d	acrB^d	AcrR^e	Binding site
13-PLS-6	Resistance	256	Low	8.2	1.6 ± 0.2^*	1.8 ± 0.2^*	WT	WT
14-PLS-21	Resistance	>512	Low	8.7	3.9 ± 0.3^*	2.7 ± 0.2^*	WT	WT
16-PLS-45	Resistance	>512	Low	6.5	1.5 ± 0.1^*	1.9 ± 0.3^*	Q78ter	WT
16-PLS-46	Resistance	>512	Low	6.6	2.4 ± 0.2^*	2.4 ± 0.4^*	Q78ter	WT
sal-1372	Resistance	>512	Low	6.3	1.8 ± 0.1^*	2.2 ± 0.2^*	WT	WT
16-PLS-33	Resistance	>512	Low	5.1	1.5 ± 0.1^*	1.9 ± 0.2^*	Q78ter	WT

ZSC-8	Susceptible	8	Low	8.1	1.7 ± 0.1^*	1.8 ± 0.2^*	Q78ter	WT
582	Susceptible	8	Low	7.2	1.4 ± 0.1^*	1.4 ± 0.2^*	Q78ter	WT

143	Susceptible	8	Intermediate	9.1	1.1 ± 0.1	1.3 ± 0.1	Q78ter	WT
ZSC-12	Susceptible	4	Intermediate	9.5	1.0 ± 0.1	1.0 ± 0.1	Q78ter	WT
1002	Susceptible	4	Intermediate	9.8	1.1 ± 0.2	1.2 ± 0.2	Q78ter	WT

916	Susceptible	4	High	10.7	1.1 ± 0.1	1.1 ± 0.1	Q78ter	WT
03-197-1	Susceptible	2	High	11.4	0.9 ± 0.1	0.8 ± 0.1	Q78ter	WT
03-228-1	Susceptible	2	High	10.7	1.0 ± 0.2	1.1 ± 0.1	Q78ter	WT
ZSC-14-1	Susceptible	4	High	11.0	0.9 ± 0.1	1.1 ± 0.1	Q78ter	WT
ZSC-40	Susceptible	4	High	10.5	0.9 ± 0.2	0.9 ± 0.2	WT	WT
419	Susceptible	4	High	12.7	1.0 ± 0.2	0.9 ± 0.1	Q78ter	WT

MIC, minimum inhibitory concentration; WT, wild-type sequence.

^aMIC break point of nalidixic acid is 32 mg/L.

^bData from a previous report (Asai et al., 2010).

^cData from a previous report (Usui et al., 2009).

^dRelative expression level compared to the average for six high enrofloxacin-accumulating nalidixic acid-susceptible strains.

^eQ78ter, stop codon mutation, glutamine-78-termination.

*Indicates mRNA expression is significantly higher than mRNA expression of six high enrofloxacin-accumulating nalidixic acid-susceptible strains (P < 0.05).