Expression of type 1 and P fimbriae in situ and localisation of a uropathogenic Escherichia coli strain in the murine bladder and kidney

Adhesion is an important aspect of bacterial colonisation and induction of human disease. Escherichia roll which infects and causes disease of the uri nary tract expresses several adherence factors including type 1 and P fimbr iae. Their expression has been implicated in the virulence of E. coli strai ns infecting the urinary tract, however, the evidence for the expression of these fimbriae in situ has been implied rather than proven. Here we descri be in situ detection of E. coli and of fimbrial expression in urinary tract tissue. Kidneys and bladders were isolated from mice infected with the uro pathogenic isolate E. coli AD110. The tissue was sectioned and subjected to DNA-rRNA hybridization and indirect immunofluorescent staining with antibo dies against type 1 and P fimbriae. Sections of both kidney and bladder sta ined positive for bacterial cells using a Cy3-labelled E. coli-specific rRN A probe. The same cells in these sections also stained positive for type I or P fimbriae using fluorescein-labelled antibodies. Tissue taken from seve ral different time points (2, 6, and 24 hours post infection) showed the pr esence of bacterial cells which stained positive for fimbrial expression. B acteria in kidney and bladder sections were observed either as individual c ells associated with the mucosa or as members of microcolonies.