Background/aim: Escherichia coli is the most frequent cause of urinary tract infections. We investigated the possible associations between the origin of strains, antimicrobial resistance, the presence of urovirulence factors, and biofilm-forming ability. Materials and methods: Antibiotic susceptibility of E. coli strains was tested by disk diffusion method. Hemagglutination assays were performed for phenotypic characterization of the cell surface. Multiplex PCR was used for detection of virulence genes and for determination of phylogenetic relationships. Results: The resistance to ampicillin (55.5%) and tetracycline (39.3%) was significantly more frequent than to other antimicrobial agents. The fim gene was present in 92.5% of strains. The sfa and pap genes were found in 53.8% and 38.7% of strains, respectively. The pap gene was significantly less frequently detected in strains from dialysis patients. The hly gene was present in 18.5% of strains. The aer gene was detected in 52.6% and cnf in 12.1%, while afa was detected in 4.6% of strains. Most strains belonged to the B2 and D phylogenetic groups. The aer gene was significantly associated with strains producing strong biofilms. Conclusion: The E. coli strains causing cystitis in hospitalized patients differed in terms of resistance to antibiotics, virulence genes, and potential for biofilm formation.