In vitro activity of E-4868, a new fluoroquinolone with a 7-azetidin ring, compared with ciprofloxacin, ofloxacin and fleroxacin.

E-4868, (-)-7[3-(R)-amino-2-(S)-methyl-1-azetidinyl]-1-(2,4- difluorophenyl)-1,4-dihydro-6-fluoro-4-oxo-3-quinolinecarboxylic acid, is a new fluoroquinolone with a 7-azetidin ring substituent. The in vitro activity against clinical isolates was compared with that of ciprofloxacin, ofloxacin and fleroxacin. In general, activity of E-4868 against aerobic and facultative anaerobic Gram-negative bacilli was equal to or slightly less active than ciprofloxacin with the exception of Morganella morganii and Proteus spp., E-4868 MIC90, 1 and 0.5 microgram/ml, respectively. E-4868 activity was two- to eight-fold higher than ciprofloxacin against Gram-positive cocci. For anaerobic species, E-4868 activity was comparable to that of ciprofloxacin, although against the Bacteroides fragilis group E-4868 was four-fold more active than ciprofloxacin.