Urinary-tract infection: localisation and virulence of Escherichia coli.

Virulence of 15 strains of Escherichia coli from the human upper urinary tract was compared with that of 16 strains from the lower urinary tract, using an ascending infection in the mouse. No significant difference was found. There was no significant difference in frequency of K antigen and ability to ferment dulcitol between 32 lower strains and 31 upper strains. However, 22 strains containing K antigen, regardless of anatomical site of localisation, were more significantly likely to cause infection than 9 strains with no antigen. Similarly, 23 dulcitolfermenting strains, regardless of site of localisation, were significantly more likely to cause infection than 8 non-fermenting strains.