Biofilm and Curli Formation among Ecshrichia coli Strains Isolated from Urinary Infections in Tehran. 2016

Bacterial biofilms are associated with a large number of persistent and chronic infections. Biofilm forming bacteria are particularly resistant to antibiotics and immune defenses, which makes it hard to treat and eradicate biofilm-associated infections. The aim of this study was to investigate the biofilm and curli formation among Escherichia coli strains isolated from urinary infections in Tehran during 2016. A total of 200 urine samples were collected from patients with urinary tract infections from in Tehran and E. coli isolates were identified using specific primers. The ability of E. coli strains to form biofilm, curli and cellulose was measured using qualitative CongoRed agar and quantitative microtiter plate assays. Amongst all isolates, 124 strains (62%) were identified as E. coli and 16 (13%), 19 (15%) and 11 (9%) were able to form biofilm and harbored rdar, bdar and pdar morphotypes, respectively. On the other hand, 78 strains (63%) were not able to form biofilm. Moreover, using microtiter plate assay 15 and 39% of strains were able to form strong and low level biofilm, respectively. Our findings illustrated the important role of curli and cellulose in attachment and biofilm formation among E. coli strains isolated from patients with UTI infections