Virulence Genes, Genetic Diversity, Antimicrobial Susceptibility and Phylogenetic Background of Escherichia coli Isolates

Background: The epidemiology of Uropathogenic Escherichia coli (UPEC) in urban and rural communities in Iran was never investigated prior to this study. Objectives: The aims of this study were to detect the frequency of virulence genes and determine the antimicrobial susceptibility and phylogenetic background of Escherichia coli isolates collected from urban and rural communities. Materials and Methods: A total of 100 E. coli isolates were collected from urine samples of patients with urinary tract infections (UTIs) residing in two different locations, and confirmed by current biochemical tests. The phylogenetic groups were determined by the triplexpolymerase chain reaction (PCR) method, and multiplex PCRs were used to detect eight Vf genes (fimH, iucD, irp2, hlyA, ompT, iha, iroN, and cnf1). The susceptibility profile of E. coli isolates was determined by the disk diffusion method. Results: Ninety-five percent of UPEC showed at least one of the virulence genes, the most prevalent being fimH (95%), followed by irp2 (89%), iucD (69%), ompT (67%), iroN (29%), and iha (29%). The various combinations of detected genes were designated as virulence patterns. Phylogenetic groups, B2 (55%) and D (22%), comprised the majority of isolated strains. Phenotypic tests showed that 92%, 74% and 71% of the isolates were resistant to ampicillin, ceftizoxime and cefixime, respectively. Conclusions: These findings indicate that the UPEC isolates had eight virulence factors with high frequencies. Moreover, these results suggest a direct connection between virulence factors, gene diversity, phylogenetic background, and antimicrobial resistance in UPEC isolates.