Activities of fluoroquinolones and diones against M. smegmatis mutants. The MICs of each compound with wild-type M. smegmatis and three GyrA variants, KD2008 (G89C) (shaded bars), KD1987 (A91V) (filled bars), and KD1991 (D95Y) (open bars), were determined. Then the ratio of the MIC with the mutant to the MIC with the wild type was calculated. Compounds are grouped in panels according to the C-7 ring structure. (A) Compounds in the moxifloxacin series (R1 = a); (B) compounds in the PD161148 series (R1 = b); (C) compounds in the UING5-207 series (R1 = d, except for UING5-159). Similar results were obtained in replicate experiments.