Prevalence, resistance profiles, virulence gene complements, and phylogenetic and clonal affinities of fluoroquinolone-resistant Escherichia coli from urinary tract infections (UTIs) in Norway were investigated. Of 7302 E. coli UTI isolates from 2003, 1.2% were fluoroquinolone-resistant; 35 of these fluoroquinolone-resistant isolates were included in the present study. The isolates were predominantly multiresistant, carried few virulence factors, and tended to belong to the less-virulent phylogroups A and B1. Although the isolates were genetically heterogeneous, there was evidence of a limited degree of clonal dissemination.

We describe a study of urinary tract and intestinal isolates of Escherichia coli from Norway and Russia using automated ribotyping, single nucleotide polymorphism analysis for clonal group A (CgA) supplemented with phylogrouping, virulence gene profiling and resistance profiling. CgA comprised 19% of the Norwegian UTI isolates from 2001. Two highly multiresistant fluoroquinolone-resistant CgA isolates were found. Ribotypes clustered into four major and six minor groups (ribogroups). Fluoroquinolone-resistant isolates and phylogroups A and B1 were associated with ribogroup (R)A. Ribogroup (R)B predominated among Russian UTI isolates and was predominantly phylogroup A and depleted in P-fimbriae. Ribogroup (R)C predominated among Norwegian UTI isolates and was rich in virulence factors (S-fimbriae, haemagglutinin and haemolysin) and predominantly phylogroup B2 and D. Ribogroup (R)G was associated with CgA and predominantly phylogroup D. Ribogroups (R)D, (R)E and (R)F had too few members for statistical analysis. The correlation between ribotype and phylogenetic group was not as strong as reported in other studies.