Characterization of biofilm formation and production of extended spectrum beta lactamase enzymes in Escherichia coli strains isolated from patients with urinary infection in Zahedan during 2017

Biofilm formation is a major determinant factor in the development of urinary tract infections (UTIs) by uropathogenic Escherichia coli (UPEC). The ability of UPEC to form biofilm and produce beta-lactamases is linked to persistence and recurrence of UTIs. In this study, we investigated the prevalence of biofilm and beta-lactamase producing UPECs among patients with UTI in Zahedan.

During 2017, a total of 112 suspected E. coli isolates were collected from patients with UTIs in Imam Ali Hospital in Zahedan, and identified using common biochemical tests and also PCR by specific primers. The ability of confirmed strains to produce of curli/cellulose and form biofilm was assessed using qualitative Congo red agar (CRA) and quantitative microtiter plate (MTP) methods, respectively. Extended-spectrum beta-lactamase (ESBL) phenotypic production and antibiotic susceptibility of biofilm producing strains were investigated using disk diffusion method by the guidelines of CLSI.

A total of 85 isolates (76%) were identified and confirmed as UPEC strains using standard biochemical and molecular confirmatory diagnostic tests. The prevalence of BFP strains was very high, as 58 strains (68%) produced curli and/or cellulose and were able to produce biofilm. BFP strains showed high resistance (80-99%) to ampicillin, cefotaxime, cefpodoxime, ceftazidime and ceftriaxone. Moreover, 62% of strains were able to produce ESBL, and also a significant association between the strong biofilm and ESBL production was found.

The high prevalence of biofilm and ESBL producing UPEC strains isolated from patients with UTI in Zahedan, might be in part due to low socioeconomic status and also warm climate of this city.