In vitro antibacterial activity of E-3604, a new 6-fluoroquinolone, on clinical isolates

From a series of pyrrol-containing antibacterial agents, E-3604 was selected for development and compared with nalidixic acid, norfloxacin and ciprofloxacin against strains of clinical isolates. The in vitro activity of E-3604 was greater than that of nalidixic acid, similar to that of norfloxacin and lower than that of ciprofloxacin, except in the case of Staphylococcus where E-3604 showed the best in vitro activity of all the studied compounds, with a MIC range of 0.25-0.03 mg/ml. E-3604, like the other quinolones, presented a pH-dependent variation of activity, greater activity being observed in slightly acidic pH values.