Pathogenesis of Escherichia coli cystitis and pyelonephritis: apparent lack of significance of bacterial motility and chemotaxis towards human urine.

All 45 microscopically motile urinary isolates tested here (37 Escherichia coli, two Enterobacter cloacae, two Citrobacter freundii, three Proteus mirabilis and one Proteus morganii) were strongly attracted to fresh human urine in a capillary chemotaxis assay. This observation suggested that urine taxis of gram-negative bacteria promotes their invasion of the human lower urinary tract and their ascension to the kidney(s). However, the incidence of motile isolates and their activity in urine taxis assays were similar for fecal E. coli isolates, for isolates from patients with recurrent cystitis and from patients with presumed pyelonephritis (E. coli blood isolates with concomitant E. coli bacteriuria). Thus, the present study of E. coli did not support the hypothesis that bacterial motility is a virulence factor in urinary tract infection.