In vitro antibacterial activities of broad spectrum quinolones against clinical bacterial isolates

In vitro activities of broad-spectrum quinolones (sparfloxacin (SPFX), ciprofloxacin (CPFX), lomefloxacin (LFLX), fleroxacin (FLRX), and levofloxacin (LVFX) were examined against clinical bacterial isolates: Klebsiella pneumoniae, Haemophilus influenzae, Moraxella subgenus Branhamella catarrhalis, Methicillin-sensitive Staphylococcus aureus (MSSA), Methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Enterococcus faecium, and Streptococcus pneumoniae). Antibacterial activities of SPFX, CPFX, and LVFX against Gram-negative bacteria such as K. pneumoniae, M. (B) catarrhalis and H. influenzae were better than those of FLRX and LFLX. SPFX showed the highest activity against all Gram-positive bacteria tested in this study. However, strains showed high MIC (> or = 16 micrograms/ml) to SPFX were found among MRSA, E. faecalis, and E. faecium, whose isolation frequencies were 28.6%, 10.0%, and 6.7%, respectively. The results of this study suggest that resistant strains of Gram-positive bacteria against new quinolone might increase among clinical isolates.