RESUMEN
This study was carried out on 39 urinary E. coli and 31 E. coli isolated from feces of normal individuals. Properties of E. Coli considered to be important in the pathogenesis of upper urinary tract infection were investigated. The properties which were found to be significantly more common in the urinary strains than in the fecal strains included production of hemolysin, pellicle formation, mannose sensitive hemagglutination and sensitivity to serum. On the other hand, no significant differences were found as regards sugar fermentation and sensitivity to urea and serine. Strains rich in the combination of these pathogenic properties were significantly more common among the urinary strains indicating that these properties might confer to them a greater ability to invade the urinary tract