Table 3.

Activities of gatifloxacin and its related compounds against target-altered mutant strains

Straina (amino acid substitutions)MIC (μg/ml)
GatifloxacinAM-1121AM-1147Ciprofloxacin
Wild-type strain IID553 (ParC, none; GyrA, none)0.390.780.390.78
First-step mutant strains
 NF9884 (ParC, S79Y; GyrA, none)0.393.130.393.13
 LF9853 (ParC, D83N; GyrA, none)0.393.130.393.13
 SF9863 (ParC, none; GyrA, S81F)0.781.560.781.56
 GF9821 (ParC, none; GyrA, S81Y)0.781.560.781.56
Second-step mutant strains
 NG9951 (ParC, S79Y; GyrA, S81F)6.25256.2525
 NG9952 (ParC, S79Y; GyrA, E85K)6.252512.525
 ST9941 (ParC, S79F; GyrA, S81F)6.25256.2525
 SN9981 (ParC, D83Y; GyrA, S81F)3.13253.1312.5
  • a NF9884, LF9853, SF9863, and the second-step mutant strains were obtained in previous experiments (8, 9).