Comparison of antibacterial activity of fluoroquinolones with their sucralfate-complexes against clinically-isolated bacteria

Oral fluoroquinolones are widely known to form chelate complexes with metal-containing drugs, resulting in inhibition of their intestinal absorption. However, for intestinal sterilization, the concomitant regimen may be a selective and effective strategy due to decreased absorption of fluoroquinolones result in the retainment of antibiotics at the intestine if the mixture still perpetuated antibacterial activity. Therefore, to clarify whether the mixture of fluoroquinolones and sucralfate affects their antibacterial activity or not, we conducted in vitro study. According from the checkerboard study using a microdilution method with Mueller-Hinton broth, the antibacterial activity of these fluoroquinolones-sucralfate mixtures equaled to the parent fluoroquinolones even in the presence of sucralfate at the molar ratio of [sucralfate : fluoroquinolone] was less than 166, and the minimal inhibitory concentrations for clinical isolated Escherichia coli and Pseudomonas aeruginosa strains were independent of the existence of sucralfate. These data imply that the chelated forms of each fluoroquinolone retain antibacterial activity even in the presence of the recommended therapeutic doses of sucralfate in clinical practice.