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

We have found in vitro that a biofilm of benign Escherichia 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. faecalis adherence by 83-fold. Mannose-fimbrial interactions were essential for the improved E. coli 83927 adherence and interference effects.From the Clinical EditorRecurrent urinary tract infections remain major adverse events associated with catheter use. The authors report that modifying catheter surface to present mannose ligands for the type 1 fimbriae of benign Escherichia coli 83972 promotes formation of dense E. coli biofilms, which 100-fold reduces urinary catheter colonization of uropathogens. Future application of this technology is expected to result in substantial UTI risk reduction in catheter users.

Graphical AbstractWe covalently immobilized a mannose derivative on silicon substrates by attaching an oligo(ethylene glycol) mannoside with an amino-terminal group onto carboxylic acid–terminated monolayers via amidation. The resulting monolayers presented mannose ligands for the receptors on the type 1 fimbriae of Escherichia coli 83972. E. coli 83972 is a benign organism, and an established biofilm of this organism can prevent surface attachment by pathogens, such as Enterococcus faecalis. Our results showed that surface modification with mannose-presenting monolayers promoted biofilm formation by the benign organism and resulted in exclusion of the pathogen from the surface, a process known as bacterial interference.Figure optionsDownload high-quality image (169 K)Download as PowerPoint slide