Interaction of a pyelonephritogenic Escherichia coli strain with the tissue components of the mouse urinary tract

Immediately following the introduction of cells of a pyelonephritogenic strain of Escherichia coli (expressing both GS and MS adhesins) into the mouse bladder, these cells were found to be randomly distributed on the mucosal surfaces of both the bladder and the kidney. After 24 hr. these adherent bacterial cells had proliferated to form nonrandomly distributed adherent microcolonies on both mucosal surfaces and large masses within the renal ducts. Large amounts of amorphous material, which we presume to be of both host and bacterial origin, was associated with the bacterial microcolonies on the infected tissues. The removal of urinary slime and tissue coat material by acid pretreatment increased both the degree and the apparent avidity of bacterial adhesion to the bladder mucosa. The adherent bacteria on the bladder mucosa were radically elongated, while those on the kidney mucosa usually retained their short rod-like morphological characteristics. These data suggest that pyelonephritogenic bacteria adhere to mucosal surfaces in both the bladder and kidney, and proliferate to form adherent microcolonies within which bacteria are associated with large amounts of amorphous extracellular material.