TABLE 4.

Frequency of appearance of quinolone-resistant strains from the wild type and each mutant strain of MS5952 by selection with various quinolones

Strain	Quinolone	Frequency at the following multiple of the MICa:
		4×	8×	16×	32×	64×
Wild	Gatifloxacin	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
	Norfloxacin	3.3 × 10−8	1.0 × 10−8	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
	Ofloxacin	1.5 × 10−8	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
	Ciprofloxacin	3.9 × 10−8	1.0 × 10−9	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
	Tosufloxacin	4.8 × 10−8	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
	Sparfloxacin	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10	<5.0 × 10−10
First-step mutant	Gatifloxacin	8.5 × 10−9	1.9 × 10−9	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10
	Norfloxacin	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10
	Ofloxacin	2.3 × 10−9	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10
	Ciprofloxacin	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10
	Tosufloxacin	8.0 × 10−8	1.9 × 10−8	<3.8 × 10−10	<3.8 × 10−10	<3.8 × 10−10
	Sparfloxacin	>3.8 × 10−7	1.7 × 10−8	5.4 × 10−9	3.5 × 10−9	2.7 × 10−9
Second-step mutant	Gatifloxacin	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10
	Norfloxacin	9.3 × 10−8	1.5 × 10−9	<1.9 × 10−10	NDb	ND
	Ofloxacin	5.9 × 10−8	1.3 × 10−9	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10
	Ciprofloxacin	1.9 × 10−7	3.8 × 10−8	<1.9 × 10−10	<1.9 × 10−10	ND
	Tosufloxacin	>1.9 × 10−7	3.7 × 10−8	<1.9 × 10−10	ND	ND
	Sparfloxacin	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10	<1.9 × 10−10

^aThe reproducibilities of the frequencies have been confirmed in repeat experiments. 

^bND, not determined because those quinolones did not dissolve in the medium.