Phylogenetic Grouping and Assessment of Virulence Genotypes, With Antibiotic Resistance Patterns, of Escherichia Coli Strains Implicated in Female Urinary Tract Infections

Abstract

Background: Escherichia coli strains are common pathogens that can cause urinary tract infections (UTIs). They are classified into phylogroups based on three genetic markers: chuA, yjaA, and TspE4.C2. The E. coli strains that cause UTIs possess several genes that encode urovirulent factors and antimicrobial-resistance phenotypes. We determined the phylogenetic groups of E. coli isolates from UTI cases in Sabzevar, Iran, the prevalence of certain virulence genes, and the antibiotic-resistance phenotypes in these strains. Objectives: The aim of this study was to assess the correlation of detected E. coli phylogroups in female UTI patients with the antibioticresistance pattern and the distribution of certain virulence factors among the phylogroups. Materials and Methods: Ninety-three E. coli isolates from 150 women with UTI were studied. Three genetic markers were detected for phylogenetic grouping of strains, and four virulence determinants were analyzed with multiplex-PCR, including the genes for hemolysin (hly), aerobactin (iucD), P fimbriae (pap), and S/F1C fimbriae (sfa/focDE). The antibiotic-resistance phenotypes were also determined. Results: The isolates from UTI cases were distributed within phylogroups A (31%), B1 (10%), B2 (28%), and D (31%). The prevalence of iucD, hly, pap, and sfa/focDE virulence genes was significantly associated with groups B2 and D. The most-resisted antibiotics were cefazolin (93%) and co-trimoxazole (68%), while the isolates were most sensitive to nitrofurantoin (1%) and imipenem (2%). Conclusions: The phylogroups of E. coli isolates from UTI cases showed that groups D, B2, and A are prevalent in women in Sabzevar, as the dominant pathogenic phylogroups. The comparison showed that there was no significant difference in the occurrence of virulence factors or in the distribution of antibiotic resistance between urinary E. coli isolates, but the virulence genes were distributed more into groups B2 and D, respectively. Our study showed that the highest sensitivity was to nitrofurantoin and imipenem, but the decision on a treatment strategy remains based on the physician’s diagnosis and the antimicrobial-resistance tests.