Comparison of the bactericidal activity of trovafloxacin and ciprofloxacin, alone and in combination with cefepime, against Pseudomonas aeruginosa

Background: Although ciprofloxacin exhibits more intense microbiological ac tivity against Pseudomonas aeruginosa than does trovafloxacin, the clinical relevance of this observation remains questionable, particularly when the agents are combined with another antipseudomonal agent. Methods:To evaluate this further, we conducted a four-way crossover trial to compare the bacte ricidal activities of ciprofloxacin and trovafloxacin, alone and in combina tion with cefepime, against three clinical isolates of P. aeruginosa. Healt hy subjects received the following regimens, dosed to steady state: trovafl oxacin 300 mg/24 h; ciprofloxacin 400 mg/12 h; trovafloxacin 300 mg/24 h pl us cefepime 2 gl 12 h, and ciprofloxacin 400 mg/12 h plus cefepime 2g/12h. Serum bactericidal titers were performed with each regimen. Results: As mon otherapy, the area under the bactericidal curve for ciprofloxacin exceeded that of trovafloxacin for all isolates. No significant difference in the ov erall degree of bactericidal I activity was noted for two of th ree P. aeru ginosa isolates for the combination regimens. Additionally, both combinatio n regimens provided bactericidal activity for 100% of the dosing interval f or all isolates. Conclusion: These results indicate that, while in vitro di fferences exist among these quinolones for P. aeruginosa, when a fluoroquin olone is combined with a beta -lactam, this is likely to be of little clini cal significance. Copyright (C) 2000 S. Karger AG, Basel.