[In vitro study of the effects of oxolinic acid at sub-inhibitory concentrations on the activity of hemagglutinins and adhesion to uroepithelial cells by Escherichia coli isolated from urine].

The aim of the present study was to investigate the effects of sub-MIC doses of oxolinic acid (quinolone), widely used in the treatment of urinary tract infections, on both haemagglutinating activity and adhesion capacity of 13 Escherichia coli strains isolated from urine during acute cystitis or pyelonephritis. All these strains adhered to uroepithelial cells and showed mannose-sensitive and/or mannose-resistant haemagglutinating activity. Sub-MIC doses of oxolinic acid induced filaments in most of the bacterial cultures; however, inhibition of haemagglutination and adhesion was variable in vitro. When inhibition did take place in any one strain, both haemagglutination and adhesion were affected. These results confirm those of other authors and indicate that the effect of sub-MIC doses of a given antibiotic is strain-specific; they also indirectly show the heterogeneity of E. coli strains isolated from urine. It thus seems unlikely that, in clinical conditions, a single antibiotic is capable of reducing adhesion, given the diversity of the adhesins found in pathogenic E. coli strains.