Table 1. MIC of antibiotics, antiseptics, and dyes against L. monocytogenes clinical isolates BM4715 and BM4716 as well as BM4715 fepR deletion mutant (BM4715ΔfepR).

Compounda	MIC (mg/L)b
	BM4715		BM4716		BM4715ΔfepR
	−R	+R	−R	+R	−R	+R
FQ antibiotic
Norfloxacin	4	2 (2)	128	8 (16)	64	4 (16)
Ciprofloxacin	0.5	0.5 (1)	32	2 (16)	16	1 (16)
Sparfloxacin	1	1 (1)	2	2 (1)	2	2 (1)
Levofloxacin	1	1 (1)	2	1 (2)	2	1 (2)
Moxifloxacin	0.25	0.25 (1)	0.5	0.25 (2)	0.5	0.25 (2)
Non-FQ antibiotic
Amoxicillin	0.25	0.25 (1)	0.25	0.25 (1)	0.25	0.25 (1)
Cephalothin	2	2 (1)	2	2 (1)	2	2 (1)
Gentamicin	0.5	0.5 (1)	1	1 (1)	1	1 (1)
Erythromycin	0.25	0.25 (1)	0.25	0.25 (1)	0.25	0.25 (1)
Clindamycin	2	2 (1)	2	2 (1)	2	2 (1)
Chloramphenicol	4	4 (1)	4	4 (1)	4	4 (1)
Tetracycline	0.5	0.25 (2)	0.5	0.25 (2)	0.25	0.25 (1)
Tigecycline	0.12	0.12 (1)	0.12	0.06 (2)	0.06	0.06 (1)
Vancomycin	1	1 (1)	1	1 (1)	1	1 (1)
Linezolid	2	2 (1)	2	2 (1)	2	2 (1)
Daptomycin	1	0.5 (2)	1	0.5 (2)	1	0.5 (2)
Cotrimoxazole	0.03	0.03 (1)	0.06	0.03 (2)	0.03	0.03 (1)
Rifampin	0.06	0.06 (1)	0.06	0.06 (1)	0.06	0.06 (1)
Fusidic acid	2	2 (1)	2	2 (1)	2	2 (1)
Fosfomycin	≥1,024	≥1,024 (1)	≥1,024	≥1,024 (1)	≥1,024	≥1,024 (1)
Antiseptic
Benzalkonium chloride	4	2 (2)	8	8 (1)	8	8 (1)
Cetylperidinium chloride	2	2 (1)	8	4 (2)	8	4 (2)
Chlorhexidine	2	2 (1)	8	8 (1)	8	8 (1)
Tetraphenylphosphonium	128	64 (2)	256	128 (2)	128	64 (2)
Dye
Acridine orange	256	128 (2)	256	128 (2)	256	128 (2)
Acriflavine	64	64 (1)	128	128 (1)	64	64 (1)
Crystal violet	4	4 (1)	8	8 (1)	4	4 (1)
Ethidium bromide	32	16 (2)	256	128 (2)	256	128 (2)
Rhodamine	16	8 (2)	16	8 (2)	16	8 (2)

^aFQ, fluoroquinolone.

^bMICs determined in the presence (+R) or absence (−R) of reserpine (10 mg/L). Values in parentheses indicate the n-fold decrease in MIC in the presence of reserpin compared to its absence. Values in bold indicate significant changes in MIC.