Abstract
The antimicrobial activity of pazufloxacin (PZFX), a new quinolone, was determined against 769 recent clinical isolates and compared with those of norfloxacin, ofloxacin, levofloxacin, ciprofloxacin, tosufloxacin, fleroxacin and sparfloxacin. PZFX showed superior antimicrobial activity against the species of Streptococcus and Enterococcus, and the MICs90 of PZFX against methicillin-sensitive and methicillinresistant Staphylococcus aureus were 0.2 and 12.5μg/ml, respectively. The MICs of PZFX against most species of Enterobacteriaceae were less than 3.13μg/ml. PZFX showed the equal or the highest antimicrobial activity against the species of Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae, Proteus mirabilis, Morganella morganii and Serratia marcescens among the agents tested.
Resistance to PZFX was induced in stepwise fashion in broth cultures of S. aureus, E. coli and Pseudomonas aeruginosa strains, indicating that the rate was very slow, and the increased level of resistance did not exceed fourfold.
The in vitro postantibiotic effect (PAE) of PZFX was evaluated. When strains of E. coli, Klebsiella pneumoniae and P. aeruginosa were exposed to PZFX at 2 MICs for 2 hours, the durations of PAE were 1.3, 1.6 and 1.7 hours, respectively, and PZFX tended to show a slightly shorter duration of PAE than the reference quinolones.
Although PZFX alone had no bactericidal activity against the sessile cells of the P. aeruginosa strain tested, PZFX showed synergistic bactericidal activity when combined with sub-MICs of erythromycin or clarithromycin.
