Nanoscale surface modification favors benign biofilm formation and impedes adherence by pathogens

We have found in vitro that a biofilm of benignEscherichia coli 83972 interferes with urinary catheter colonization by pathogens, and in human studies E. coli 83972–coated urinary catheters are associated with lower rates of catheter-associated urinary tract infections. We hypothesized that modifying surfaces to present mannose ligands for the type 1 fimbriae of E. coli would promote formation of dense E. coli 83972 biofilms, thereby interfering with surface colonization by Enterococcus faecalis, a common uropathogen. We covalently immobilized mannose on silicon substrates by attaching amino-terminated mannose derivative to carboxylic acid–terminated monolayers via amidation. Fluorescence microscopy showed that E. coli 83972 adherence to mannose-modified surfaces increased 4.4-fold compared to unmodified silicon surfaces. Pre-exposing mannose-modified surfaces to E. coli 83972 established a protective biofilm that reduced E. faecalisadherence by 83-fold. Mannose-fimbrial interactions were essential for the improved E. coli 83927 adherence and interference effects.