Inhibition of motility and adherence of Proteus mirabilis to uroepithelial cells by subinhibitory concentrations of amikacin.

The effect of subinhibitory concentrations of amikacin on Proteus mirabilis motility and adherence to human uroepithelial and to HeLa cells was compared with that of gentamicin. In addition, the effect of both antibiotics on cell surface hydrophobicity was also examined. Exposure of bacterial cells in the logarithmic phase to one fourth of amikacin or gentamicin at one fourth of their respective minimal inhibitory concentrations causes the inhibition of swarming and motility of Proteus strains. Amikacin significantly reduced adhesion of Proteus strains to human uroepithelial cells and gentamicin exerts the same effect to a lesser extent. Such inhibitory concentrations of amikacin or gentamicin had no significant effect on the attachment ability of these strains to HeLa cells compared to the nontreated cells. Treatment of the bacterial cells with amikacin or gentamicin changed significantly the cell surface hydrophobicity towards the hydrophilic state compared to nontreated cells, and it was found to be strain dependent. Since motility and attachment ability are considered as pathogenic traits, these data indicate the impact of amikacin on the virulence factors especially in urinary tract infections with Proteus strains.