Curli fimbria: An escherichia coli adhesin associated with human cystitis

Abstract

Escherichia coli is the major causative agent of human cystitis. In this study, a preliminarymolecular analysis carried out by PCR (polymerase chain reaction) demonstrated that 100%of 31 E. coli strains isolated from patients with recurrent UTIs (urinary tract infections)showed the presence of the curli fimbria gene (csgA). Curli fimbria is known to be associ-ated with bacterial biofilm formation but not with the adhesion of human cystitis-associatedE. coli. Therefore, this work aimed to study how curli fimbria is associated with uropathogenicE. coli (UPEC) as an adhesion factor. For this purpose, the csgA gene was deleted from strainUPEC-4, which carries three adhesion factor genes (csgA, fimH and ompA). The wild-typeUPEC-4 strain and its mutant (∆csgA) were analyzed for their adhesion ability over HTB-9(human bladder carcinoma), Vero (kidney cells of African green monkey) and HUVEC (humanumbilical vein) cells in the presence of α-d-mannose. All the wild-type UPEC strains tested(100%) were able to adhere to all three cell types, while the UPEC-4 ∆csgA mutant lost itsadherence to HTB-9 but continued to adhere to the HUVEC and Vero cells. The results suggestthat curli fimbria has an important role in the adhesion processes associated with humanUPEC-induced cystitis.