Postantibiotic effect of DU-6859a and levofloxacin as compared with ofloxacin.

The postantibiotic effect (PAE) was determined for two of the newer fluoroquinolones: DU-6859a and levofloxacin. All drugs (including ofloxacin control) had good PAE activity against Escherichia coli and Staphylococcus aureus. Only DU-6859a had PAE test conditions (< or = 0.5 mu/ml) that coincided with achievable clinical concentrations for all organisms tested. These data indicate that levofloxacin, like ofloxacin (PAEs, 1.0-2.9 h), could be administered once or twice daily and that the dosing of DU-6859a (PAEs, 1.6-2.4 h) might be extended to once every 24 h because of its documented PAE and its potency advantages as compared with levofloxacin and ofloxacin.