[In vitro effect of various antibiotics: beta lactams, aminoglycosides and fluoroquinolones alone and in combination against P. aeruginosa isolated from patients with mucoviscidosis].

The antibacterial activity of fluoroquinolones (ciprofloxacin and ofloxacin) combined with beta lactams (ceftazidime and imipenem) or aminoglycosides (tobramycin and amikacin) against 22 P. aeruginosa isolated from the sputum of patients with cystic fibrosis was determined by the checkerboard method and compared with the combination of beta lactams (with ticarcillin) with aminoglycosides. Synergistic association (defined as FIC index less than ou = 0.5) was founded for 23 to 41% of strains with beta lactams (except imipenem)/aminoglycosides, in 18% with ceftazidime/ciprofloxacin, in 13% with imipenem/ciprofloxacin, in 0 or 13% with quinolones/aminoglycosides. For a FIC index less than ou = 0.75, the values are highest with 82% for ciprofloxacin/ceftazidime and 50% for ofloxacin/ceftazidime. The CMI's achieved in these combinations may allowed concentrations near to sputum concentrations.