Comparative in vitro activities of five quinolone antibiotics, including gemifloxacin, against clinical isolates

Abstract

The in vitro activities of ciprofloxacin, ofloxacin, norfloxacin, levofloxacin and gemifloxacin against 343 clinical isolates were compared. Gemifloxacin showed the greatest activity, with MIC90 values as low as 0.03-0.25 mg/L against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, methicillin-susceptible Staphylococcus aureus and Klebsiella pneumoniae, while methicillin-resistant Staphylococcus aureus, Enterococcus spp., Pseudomonas spp., Acinetobacter spp., Escherichia coli and Enterobacter spp. strains exhibited low rates of susceptibility to all five fluoroquinolones.