Pathogenetic aspects of uncomplicated urinary tract infection: recent advances.

Urinary tract infections mostly are caused by Enterobacteriaceae; E. coli dominating in 80-90% for uncomplicated diseases. Microorganisms possessing the ability to colonize the uroepithelium (fimbriae/pili) and to cytotoxically damage cells and tissue (hemolysin) may initiate acute infection. Properties such as serum resistance, iron sequesteration, hydroxamate production and the presence of K-antigen are found in strains which persist in the host without initiating clinical symptoms. The ability of bacteria to adhere to cells of the epithelial boundary layer of the host organisms is of initial importance in the origin and progress of an infection. A variety of specific factors, e.g. glycolipids on the surface of the uroepithelium as well as cellular and humoral disorders of immunoreactions in the host determine the course of a disease. The immune response may ameliorate clinical symptoms and select urovirulent characteristics of the causative microorganism in recurrent diseases.