Role of capsular colanic acid in adhesion of uropathogenic Escherichia coli

Andrea Hanna, Michael Berg, Valerie Stout, Anneta Razatos

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


Urinary tract infections are the most common urologic disease in the United States and one of the most common bacterial infections of any organ system. Biofilms persist in the urinary tract and on catheter surfaces because biofilm microorganisms are resistant to host defense mechanisms and antibiotic therapy. The first step in the establishment of biofilm infections is bacterial adhesion; preventing bacterial adhesion represents a promising method of controlling biofilms. Evidence suggests that capsular polysaccharides play a role in adhesion and pathogenicity. This study focuses on the role of physiochemical and specific binding interactions during adhesion of colanic acid exopolysaccharide mutant strains. Bacterial adhesion was evaluated for isogenic uropathogenic Escherichia coli strains that differed in colanic acid expression. The atomic force microscope (AFM) was used to directly measure the reversible physiochemical and specific binding interactions between bacterial strains and various substrates as bacteria initially approach the interface. AFM results indicate that electrostatic interactions were not solely responsible for the repulsive forces between the colanic acid mutant strains and hydrophilic substrates. Moreover, hydrophobic interactions were not found to play a significant role in adhesion of the colanic acid mutant strains. Adhesion was also evaluated by parallel-plate flow cell studies in comparison to AFM force measurements to demonstrate that prolonged incubation times alter bacterial adhesion. Results from this study demonstrate that the capsular polysaccharide colanic acid does not enhance bacterial adhesion but rather blocks the establishment of specific binding as well as time-dependent interactions between uropathogenic E. coli and inert substrates.

Original languageEnglish (US)
Pages (from-to)4474-4481
Number of pages8
JournalApplied and environmental microbiology
Issue number8
StatePublished - Aug 1 2003

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Ecology
  • Applied Microbiology and Biotechnology


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