Theodore E. Woodward Award: host-pathogen interactions in community-acquired urinary tract infections

Community-acquired urinary tract infections continue to be a significant source of morbidity and health care costs. In addition, community-acquired urinary tract infections are an excellent model for studying the interaction of the infecting bacteria and the human host. This review focuses upon five recent areas of progress in understanding host-parasite interactions in urinary tract infection. First, uropathogenic E. coli have been recognized as a specific pathogenic group of organisms characterized by the presence of pathogenecity islands, horizontally-acquired genes encoding various pathogenic phenotypes, including fimbria, other adhesins, lipopolysaccharide, the polysaccharide capsule, various toxins and hemolysins, and siderophores. Second, recent studies indicate that the epithelium plays an active role in the innate host defense against urinary infection, including secretion of chemokines and cytokines, apoptosis of epithelial cells and exfoliation of bacteria-laden epithelial cells. Third, studies in animal models indicate that uropathogenic E. coli invade epithelial cells, forming intracellular communities of organisms and eventually biofilms. These intracellular organisms may persist and form a reservoir from which recurrent infection may develop. Finally, observations suggest that some women may be genetically predisposed to recurrent urinary tract infection and the genes predisposing to recurrent infection are being sought. These new discoveries have improved our understanding of the pathogenesis of these infections and will eventually lead to improved interventions for prevention and therapy.