TABLE 1.

Quinolone antibacterial activities against target-altered mutant strains of S. aureus and inhibitory activities against type II topoisomerases

Quinolone	MIC (μg/ml) for:			IC50 (μg/ml) against:		Ratio
	Wild type	grlA mutant	gyrA mutant	DNA gyrase	Topoisomerase IV	MICa	IC50b
Nadifloxacin	0.016	0.031	0.125	3.44	19.0	4	5.52
Sparfloxacin	0.031	0.063	0.125	13.5	19.7	2	1.46
Clinafloxacin	0.016	0.063	0.063	0.915	1.62	1	1.77
Gatifloxacin	0.063	0.125	0.125	3.01	6.09	1	2.02
Moxifloxacin	0.031	0.063	0.063	3.44	7.84	1	2.28
Pazufloxacin	0.125	0.25	0.25	10.2	24.2	1	2.37
Ofloxacin	0.25	1	0.5	18.8	22.8	0.5	1.21
Levofloxacin	0.125	0.5	0.25	8.06	9.81	0.5	1.22
Grepafloxacin	0.031	0.125	0.063	28.4	23.3	0.5	0.820
Lomefloxacin	0.5	2	1	37.5	21.7	0.5	0.579
Trovafloxacin	0.016	0.063	0.031	7.13	3.02	0.5	0.424
Ciprofloxacin	0.25	2	0.5	13.5	5.76	0.25	0.427
Fleroxacin	0.5	4	0.5	82.6	31.6	0.125	0.383
Enoxacin	0.5	8	1	126	26.5	0.125	0.210
Norfloxacin	1	16	2	55.5	9.84	0.125	0.177

^aMIC ratio, MIC for gyrA mutant/MIC for grlA mutant. 

^bIC₅₀ ratio, IC₅₀ against topoisomerase IV/IC₅₀ against DNA gyrase.