Abstract
Pazufloxacin (PZFX) is a novel quinolone useful orally and parenterally. In the study described here, the in vitro activities of PZFX were compared with those of ofloxacin (OFLX), norfloxacin (NFLX), ciprofloxacin, tosufloxacin (TFLX) and sparfloxacin (SPFX). MIC90s of PZFX against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA; 47 strains), high-level resistant MRSA (64 strains), CNS (41 strains), Streptococcus pneumoniae (18strains), Streptococcus pyogenes (48 strains), Enterococcus faecalis (37 strains), Enterococcus faecium (41 strains), Escherichia coli CS2 (R+)(43 strains), Klebsiella pneumoniae (47 strains), Proteus mirabilis (48 strains), Proteus vulgaris (54 strains), Providencia rettgeri (47 strains), Morganella morganii (49 strains), Serratia marcescens (50 strains), Enterobacter cloacae (50 strains), Citrobacter freundii (50 strains), Pseudomonas aeruginosa (50 strains), Acinetobacter calcoaceticus (41 strains), Xanthomonas maltophilia (48 strains), Pseudomonas cepacia (33 strains), Haemophilus influenzae (11 strains) and Bacteroides fragilis (38 strains) were 0.39, 3.13, 0.39, 3.13, 3.13, 3.13, 6.25, 0.2, 0.1, 0.025, 0.025, 6.25, 0.2, 1.56, 0.78, 0.78, 12.5, 3.13, 0.78, 1.56, ≤0.013, and 6.25μg/ml, respectively. PZFX showed superior activity against gram-negative bacteria to other tested quinolones. The in vitro activity of PZFX against gram-positive bacteria was comparable to 2-to 32-fold greater than those of OFLX and NFLX, and 2-to 8-fold less than those of TFLX and SPFX. PZFX had an apparent synergy of bactericidal effect on E. coli cells with cultured mouse macrophages. IC50s of PZFX against HeLa, CHO-K1, and IMR-32 cells were higher than 100μg/ml, greater than those of OFLX and other new quinolones. PZFX had high selective toxicity against various bacteria but not mammalian cells.
