TABLE 3.

FRE in S. aureus ISP794 selected by BMS-284756 and ciprofloxacin

Multiple of MIC used	FRE for BMS-284756 or ciprofloxacina
	BMS-284756		Ciprofloxacin
For first-step mutants
2× MIC for parental strain	>8.0 × 10−10	5 × 10−10	>1.5 × 10−7	>6.8 × 10−7
4× MIC for parental strain	8.0 × 10−10	NDc	1.5 × 10−7	6.8 × 10−7
8× MIC for parental strain	ND	ND	ND	None
For second-step mutants
2× MIC for first-step mutant	1.4 × 10−9	1.2 × 10−9	1.3 × 10−8	1.7 × 10−8
4× MIC for first-step mutant	None	None	None	None
8× MIC for first-step mutant	None	ND	ND	None
For third-step mutantsb
2× MIC for second-step mutant	>1.3 × 10−9, >8.3 × 10−9	>4.5 × 10−9, >1.3 × 10−8	1.2 × 10−8	2.2 × 10−7
4× MIC for second-step mutant	1.3 × 10−9, 8.3 × 10−9	4.5 × 10−9, 1.3 × 10−8	None	None
8× MIC for second-step mutant	None	None	ND	ND
For fourth-step mutants
2× MIC for third-step mutant	>2.6 × 10−7, >1.3 × 10−8	>2.5 × 10−7, >6.25 × 10−9	5.8 × 10−6	1.2 × 10−6
4× MIC for third-step mutant	>2.6 × 10−7, >1.3 × 10−8	>2.5 × 10−7, >6.25 × 10−9	None	None
8× MIC for third-step mutant	2.6 × 10−7, >1.3 × 10−8	2.5 × 10−7, >6.25 × 10−9	ND	None
16× MIC for third-step mutant	ND, 1.3 × 10−8	ND, 6.25 × 10−9	ND	ND

^aFREs were determined in two separate experiments for each drug; results from both trials are shown in the two columns. 

^bTwo BMS-284756 mutants were carried forward (designated no. 6 and 10) for third- and fourth-step mutants. Each frequency was repeated twice. The first column under BMS-284756 represents mutants 6A and 6B, and the second column represents mutants 10A and 10B. 

^cND, not determined.