[The role of bacterial adhesion in urinary tract infections]

Bacteria adhere to and colonize almost any surface. The mechanism by which bacteria interact with the mucosal surface appears to involve specific molecular ligands or adhesins on the surface of the bacteria that interlock with specific receptor molecules on the surface to be colonized. Material adhesion allows the microorganisms to resist being washed away by the fluids and secretions that bathe mucosal surfaces and is a necessary prerequisite to growth, colonization, and subsequent infection. Many examples of the role of bacterial adherence to tissues of the host have been reported in the literature. The classic study is that of Smith and Linggood, who demonstrated that toxin-producing enteropathogenic Escherichia coli, which cause diarrhoea in swine, adhere selectively to the mucosal surfaces of the small intestine. Adherence is mediated by hair-like pili projecting from the surface of the cells. Production of these pili is controlled by a specific plasmid, the loss of which renders the cells avirulent although they continue to produce toxin. In addition, antibody to the pilus antigen prevents adherence and protects piglets against challenge with the piliated organisms. Thus, the adhesin is an essential virulence factor in enteropathogenic E. coli infections in swine. Similar studies in a variety of diseases including enterotoxigenic E. coli infections in men and rheumatic fever support the concept that specific bacterial adherence to host tissues is an important characteristic of many pathogenic microorganisms.