Microbiological rationale for the utilisation of prulifloxacin, a new fluoroquinolone, in the eradication of serious infections caused by Pseudomonas aeruginosa

Minimal inhibitory concentrations (MICs) of prulifloxacin were evaluated in comparison with ciprofloxacin, levofloxacin and moxifloxacin against a large collection (N = 300) of Pseudomonas aeruginosa strains characterised according to the CLSI/NCCLS microdilution method. Additional in vitro tests (time-kill curves and mutant prevention concentration (MPC) determinations) were carried out. Assuming a susceptibility breakpoint for prulifloxacin identical to that of ciprofloxacin, the new fluoroquinolone emerged as the most potent antibiotic (72% of susceptible strains versus 65%, 61% and 23% for ciprofloxacin, levofloxacin and moxifloxacin, respectively). Time-kill tests at 4× MIC confirmed the pronounced bactericidal potency of the drug against P. aeruginosa. Amongst the members of the fluoroquinolone class assessed, prulifloxacin produced the lowest MPC values (≤4 mg/L). Our in vitro results indicate that prulifloxacin represents the most powerful antipseudomonal drug available today.