Discrimination between intracellular uptake and surface adhesion of bacterial pathogens.

Most bacterial pathogens initiate infectious diseases by adhering to host cells. Bacterial adherence to nonphagocytic cells usually leads to extracellular colonization; however, many invasive microorganisms enter host cells after binding to the host cell surface. It is unclear why bacterial adherence can result in these two different fates for the microorganism. Analyses of model systems, such as the uptake of enteropathogenic Yersinia into cultured cells, indicate that the particular mammalian cell receptors bound and the nature of the binding event dictate whether the bacterium remains extracellular or enters host cells.