Pathogenic potential in catheter associated Escherichia coli is associated with separable biofilm and virulence gene determinants

Urinary catheterization facilitates asymptomatic bacterial colonization of the urinary tract and increases the risk of urinary tract infection (UTI). Differentiating catheter-associated asymptomatic bacteriuria (CAASB) from catheter-associated UTI (CAUTI) can be challenging when the presence or origins of symptoms are unclear. To determine whether strain-specific Escherichia coli characteristics are associated with CAUTI, we compared genomic composition and experimental catheter biofilm production by urinary isolates from catheterized inpatients and rectal isolates from healthy volunteers. CAUTI isolates were associated with a distinctive phylotype B2 sub-clade dominated by the multidrug resistant, pandemic ST131 lineage. While catheter biofilm formation was widespread among E. coli isolates, phylotype B2 biofilms were more extensive and biofilm-associated genes were preferentially found in B2 and ST131 isolates. Distinctive suites of iron-responsive genes were associated with both the ST131 lineage and catheter biofilm formation. Catheter biofilms produced by some CAASB strains could inhibit ST131 colonization, suggesting a potential beneficial function for these strains. These results suggest that the combination of biofilm and non-biofilm-associated gene networks in urinary E. coli influence CAUTI risk in catheterized patients.