Comparative in vitro activity of the new quinolone sparfloxacin (CI-978, AT-4140) against nosocomial gram-negative bloodstream isolates

Abstract
The in vitro activity of sparfloxacin (CI-978, AT-4140), a new quinolone which is active against gram-negative and gram-positive bacteria, and nine other broad-spectrum antibiotics was tested against 128 gram-negative nosocomial bloodstream isolates from separate patients. Sparfloxacin and ciprofloxacin were among the most potent antibiotics againstEscherichia coli (n=40),Enterobacter cloacae (n=18),Klebsiella oxytoca (n=13), andKlebsiella pneumoniae (n=19), with MIC90 values of ≤ 0.25 µg/ml. Ciprofloxacin was slightly more potent than sparfloxacin againstSerratia marcescens (n=14), the MIC90 values being 0.25 and 1.0 µg/ml respectively, although all strains were susceptible to both agents. Sparfloxacin was slightly less potent than ciprofloxacin againstPseudomonas aeruginosa (n=24), the MIC90 values being 4.0 and 0.5 µg/ml respectively. Overall, the in vitro activity of sparfloxacin compared favorably with that of ciprofloxacin and the other broad spectrum agents tested against nosocomial gram-negative bloodstream isolates.