Dose-response relationships for each of the study strains. Data are means ± SD. (A) F/10141 (MIC, 0.06 mg/liter; homozygous susceptible); (B) F/6862 (MIC, 0.125 mg/liter; homozygous susceptible); (C) F/7421 (MIC, 0.5 mg/liter; heterozygous); (D) F/9651 (MIC, 4.0 mg/liter; resistance mechanism unknown); (E) F/9464 (MIC, 8.0 mg/liter; homozygous resistant); (F) F/8341 (MIC, 64 mg/liter; homozygous resistant) (for this strain only the maximum possible dose was studied and growth was observed). The model fits from the population analysis and mean parameter estimates for each strain are shown. The EC50s vary 25-fold.