New aspects of pathogenesis of lower urinary tract infections.

Current theories about the pathogenesis and immunology of urinary tract infections (UTI) and the role of host defense mechanisms are discussed. The ascending route of infection is responsible for the vast majority of UTI, and colonization of the periurethral region by group-specific Escherichia coli precedes the development of UTI. Several bacterial virulence factors have been identified in organisms responsible for UTI. In urine, the most important inhibitory factors are a very high or low osmolality, a high urea concentration, a high organic acid concentration, and a low pH. There are many new antimicrobial agents which facilitate the process of bacterial eradication, especially of microorganisms that were resistant to previously available antibiotics.