BACTERICIDAL ACTIVITIES OF LB20304, A NEW FLUOROQUINOLONE

The time-kill curves of LB20304, a novel fluoroquinolone that has pote nt antibacterial activity against gram-positve and gram-negative bacte ria, were calculated at the concentrations of 1/4-, 1/2-, 1-, 2- and 4 -times the MIC against Staphylococcus aureus 77, Escherichia coli 3739 E, Pseudomonas aeruginosa 1912E. The bactericidal activity of LB20304 for these strains was very rapid and comparable to that of ciprofloxac in. LB20304 produced a decrease in the log(10) CFU per milliliter of g reater than or equal to 3 within 2 h at 4-times the MIC for all strain s and consitently prevented regrowth of bacteria after 24 h of incubat ion. The MBCs (Minimal Bactericidal Concentration) of LB20304 against test organisms were equal to or at most four-times higher than the MIC s.