UroPathogenic Escherichia coli (UPEC) are the main reason of urinary tract infections (UTIs) that consider as among the most prevalent pathological states in both community and hospital settings. Twenty isolates of E. coli were isolated from 50 urine samples obtained from different Hospitals at Baghdad, Iraq from patients with UTIs at (40%) isolation percentage. These isolates were diagnosed by biochemical tests, and confirmed by Analytic Profile Index (API 20E) as E. coli isolates. They were detected for the ability they had to biofilm formation by microtiter plate method. Five of them were considered as a biofilm former. These isolates were tested for the effect of ZnO on their biofilm formation pre-mature and mature biofilm by using 4 concentrations (500, 250, 125 and 62.5µg/ml). The results showed that all concentrations of ZnONPs showd antibiofilm activity against pre mature and post mature biofilm. The best effect was recorded against pre mature biofilm.

KKeywords; E. coli, UTI, Uropathogenic E. coli, Biofilm, nanoparticles, ZnO.