Table 2.

Activity of fluoroquinolones against E. coli mutants

Line	Strain*	C8-OMe†	C8-H†	C8-OMe/C8-H
ID50, μg/ml
1	DM4100 (WT)	0.12  ±  0.03	0.039  ±  0.006	3
2	GP201 (gyrAR)	1.2  ±  0.07	0.82  ±  0.039	1.5
3	KD1366 (gyrAR  parCR)‡	2.1  ±  0.27	3.1  ±  0.13	0.67
ID50 ratio
4	GP201/DM4100	10	21
5	KD1366/GP201	1.8	3.8
% survivors at 5-fold ID50§
6	DM4100 (WT)	0.07	1.15	1/16
7	GP201 (gyrAR)	0.11	6.3	1/57

^*WT, wild type; gyrA^R, Nal^R; parC^R, Cip^R. 

^†Fluoroquinolones tested were PD161148 (C8-OMe) and PD160793 (C8-H). Values of ID₅₀ are means ± SD. 

^‡Nearly identical results were obtained for the gyrA^R parC^R strain KD1368. 

^§Cells were treated with fluoroquinolone for 1 hr, after which they were diluted and plated on LB agar. Colonies were counted after 16 hr of incubation at 37°C.