[What is the cause of recurrent urinary tract infection?].

The increased susceptibility of patients prone to recurrent urinary tract infection (UTI) has been explained by an imbalance of bacterial virulence properties versus host defense capacities. In fact, the presence of certain virulence factors of the invading gram-negative bacteria (i.e. O-antigens, K-antigens, flagellae, hemolysine production, siderophores and fimbriae) determines the severity of clinical symptoms--whether UTI will present as a severe pyelonephritis or merely as an asymptomatic bacteriuria. On the other hand, an increased periurethral bacterial colonization, a deficiency of the uromucoid defense line, the increased density of globoseries glycolipids on uroepithelial cells, that function as receptors for type II mannose-resistant bacterial fimbriae and the defense defect of the uroepithelium itself contribute to the assumption that a localized defense deficiency within the non-obstructed urinary tract promotes the generalized susceptibility to recurrent UTI.