In vitro activity of WIN 49375 compared with those of other antibiotics in isolates from cancer patients

The activity of WIN 49375 [6-fluoro-1,4-dihydro-1-(methylamino)-7-(4-methyl-1-piperazinyl) -4-oxo-3-quinolinecarboxylic acid], a new synthetic quinolone, was tested in vitro against 587 clinical isolates. The MICs for 90% of isolates of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae were 0.20, 1,56, and 0.39 μg/ml, respectively. The MICs for 90% of isolates of Pseudomonas aeruginosa and Serratia marcescens were both 3.12 μg/ml. WIN 49375 was minimally active against gram-positive cocci. Its in vitro activity suggests that it may be useful for the treatment of gram-negative bacillary infections.