[Study on infectious mechanism of type 1 fimbriated Escherichia coli in experimental cystitis of mice].

The course of experimental cystitis in mice with Escherichia coli was studied by electron microscopy. The inoculated E. coli did not adhere to the intact bladder epithelium. However, when the mouse bladder was treated with trypsin, superficial cells were exfoliated, and the inoculated type 1 fimbriated E. coli adhered to the exposed intermediate cells and caused cystitis. The nonfimbriated E. coli showing no adherence to the superficial cells or intermediate cells and failed to cause cystitis. The present study demonstrated that the type 1 fimbriated E. coli play a role in causing cystitis, and the bladder superficial cells play a role in resisting the adherence of E. coli. The removal of superficial cells is essential for the adhesion and colonization of type 1 fimbriated E. coli onto the bladder epithelium in vivo.