COMPARISON OF RECALCITRANCE TO CIPROFLOXACIN AND LEVOFLOXACIN EXHIBITED BY PSEUDOMONAS-AERUGINOSA BOFILMS DISPLAYING RAPID-TRANSPORT CHARACTERISTICS

Attenuated total reflection Fourier transform infrared spectroscopy wa s used to measure transport of the fluoroquinolones (FQs) ciprofloxaci n and levofloxacin into Pseudomonas aeruginosa biofilms. Biofilms were exposed to each FQ at dose levels of 100, 250, and 500 mu g/ml for 30 min, A mathematical transport model was used to extract the diffusion coefficient, binding site density, and adsorption and desorption rate s for each experiment, Recalcitrance of the biofilms reward each FQ wa s evaluated by comparison of efficacies with planktonic bacteria, By t his criterion, biofilms were found to exhibit more recalcitrance towar d levofloxacin than ciprofloxacin under the experimental conditions. T hese results cannot be explained by the more hindered transport of lev ofloxacin, implicating the domination of physiological factors.