Prevalence of Motile E. coli Strains in UTI
Motile E. coli strains are relatively uncommon in urinary tract infections, with only 16% of UTI isolates demonstrating higher motility (≥6.6 mm motility diameter), making UTIs one of the infection types with the lowest prevalence of highly motile E. coli strains. 1
Key Findings on Motility in UTI
Lower motility strains predominate in UTIs compared to other extraintestinal infections, with only 16% classified as higher-motility strains versus 59% in spontaneous bacterial peritonitis, 34% in urosepsis, and 29% in biliary tract infections (p < 0.0001). 1
Lower-motility UTI strains compensate with different virulence factors, showing higher prevalence of afa and ompT genes (p = 0.0160 and p = 0.0497, respectively) compared to higher-motility strains. 1
Phylogenetic distribution differs by motility: Higher-motility strains show lower prevalence of phylogenetic groups A and B1, while lower-motility strains are more broadly distributed across phylogenetic groups (p = 0.018). 1
Clinical Implications
The low prevalence of highly motile strains in UTIs suggests that flagellar motility is not a critical virulence determinant for uropathogenic E. coli. 1 This contrasts with infections like spontaneous bacterial peritonitis where motility appears more important for pathogenesis.
Virulence Strategy in UTI
UTI-causing E. coli rely more heavily on adhesins, toxins, and iron-acquisition systems rather than motility for successful bladder colonization. 2
Strains causing persistent or relapsing UTIs are associated with phylogenetic group B2 and carry multiple virulence factors including adhesins (sfa/focDE, papAH), iron-uptake systems (chuA, fyuA, iroN), and toxins (cnf1, hlyD). 2
Common Pitfall
Do not assume that all uropathogenic E. coli are highly motile or flagellated—the majority are not, and successful UTI pathogenesis depends more on adherence mechanisms and other virulence factors than on bacterial motility. 1