Biofilm Formation and Frequency of Fimbrial Genes among Escherichia coli Strains Isolated from Patients with Urinary Tract Infection in Zahedan during 2017

Biofilm formation is a major determinant in the development of urinary tract infections (UTIs) by uropathogenic Escherichia coli (UPEC). Biofilm formation requires a set of genes facilitating the initial adhesion, maturation, production of the extracellular polymeric matrix and subsequent dispersal of bacteria. Several cell surface factors such as flagella, fimbriae, curli and exopolysaccharide production are involved in attachment of bacterial cells to the urinary tract and biofilm development. In this study we showed the prevalence of biofilm producing E. coli strains isolated from patients with UTI in Zahedan and also the presence of biofilm-associated genes was assessed.

During 2017, a total of 112 E. coli isolates were collected from patients with UTI in a referral hospital in Zahedan and were identified using common biochemical and PCR confirmatory diagnostic tests. The ability of E. coli strains to form curli and cellulose and also biofilm was measured using qualitative Congo red agar and quantitative microtiter plate assays, respectively. The presence of csgA, papC, fimH, sfaS and afaI biofilm-associated genes was tested by PCR assay.

A total of 85 strains (76%) were identified and confirmed as E. coli using PCR test. Amongst all, 58 strains (68%), produced curli and cellulose and were biofilm positive, in which, 7, 88 and 5% exhibited rdar, bdar and pdar morphotypes, respectively. Moreover, 52, 31 and 17% of strains were able to form strong, moderate and weak biofilm, respectively. The genes csgA, papC, fimH, sfaS and afaI were detected in 98, 79, 71, 14 and 10% of strains, respectively.

The results of the present study revealed the high prevalence of biofilm producing E. coli strains with biofilm associated genes among patients with UTI in Zahedan. The presence of such genes which are associated with bacterial attachment indicating the important role of curli and fimbria in biofilm formation during UTI infections which highlighted them as important targets for therapeutic purposes.