Hematogenous pyelonephritis in rats. IV. Relationship of bacterial species to the pathogenesis and sequelae of chronic pyelonephritis.

Despite the inherent differences in the various bacterial species responsible for human pyelonephritis, little consideration has been given to differences in the characteristics of the renal disease resulting from infection by each species. While it is possible that pyelonephritis is a single disease entity that develops in an identical fashion regardless of the type of bacteria, scattered clinical observations suggest that variations in the pathologic processes are governed to some extent by the properties of the infecting micro-organisms (1-4). In order to obtain further information on the pathologic differences resulting from renal infection by a variety of bacterial species, pyelonephritis was produced in rats by a method that allows the infection to develop without the confusing effects of surgical hydronephrosis (5). In the study described in the preceding paper in this series, remarkable differences were observed in the character of the acute and subacute renal infection produced by various strains of Escherichia coli, Proteus, Pseudomonas aeruginosa and enterococci isolated from patients with pyelonephritis (6). The present study was designed to examine the differential pathological effects of three of these species in chronic pyelonephritis in rats which were followed as long as one year after the onset of renal infection. In addition, the relationship of chronic pyelonephritis to hypertensive vascular disease was studied in an attempt to learn whether differences in bacterial species could account for the inconstant occurrence of hypertension in human chronic pyelonephritis and its absence in experimental chronic pyelonephritis due to E. coli (7).