The role of bacterial adherence in infection

The data presented in this review indicate that bacteria have developed mechanisms to facilitate adherence to target mammalian cells, often present in filamentous structures of varying organization at the cell surface, classified together as adhesins. These may contain distinctive molecular sequences, often including sugars, which function as ligands for specific interactions with receptors on mammalian cells. Such receptor-ligand interactions determine species, organ, and cell specificity of adherence by individual bacterial strains. In some examples, this adherence phenomenon can be demonstrated to be an essential virulence attributed of pathogens which must adhere in order to colonize and then cause disease. While considerable detailed knowledge has accumulated about certain adhesins (e.g., K-88) or some mammalian cell receptors (e.g., the pk blood group-related disaccharide on human erythrocytes for pyelonephritis strains of E. coli), in no instance do we know the nature of an adhesin and its specific receptor to fully define the actual chemistry of the binding, but we undoubtedly will in the near future. Avidity of adherence is attributable to multiple forces, in particular hydrophobic interactions in prokaryote-eukaryote systems. Therapeutic strategies to alter these relationships and thereby to prevent or treat disease are already being applied to model in vitro and experimental in vivo infections.