Bactericidal activities of LB20304, a new fluoroquinolone

The time-kill curves of LB20304, a novel fluoroquinolone that has potent antibacterial activity against gram-positve and gram-negative bacteria, were calculated at the concentration of 1/4-, 1/2-, 1-, 2- and 4-times the MIC againstStaphylococcus aureus 77, Escherichia coli, 3739E,Pseudomonas aeruginosa 1912E. The bactericidal activity of LB20304 for these strains was very rapid and comparable to that of ciprofloxacin. LB20304 produced a decrease in the log₁₀ CFU per milliliter of ≥3 within 2 h at 4-times the MIC for all strains and consitently prevented regrowth of bacteria after 24 h of incubation. The MBCs (Minimal Bactericidal Concentration) of LB20304 against test organisms were equal to or at most four-times higher than the MICs.