Technical Report: A Novel Porcine Model of Acute Pyelonephritis

Abstract

A porcine model of acute Escherichia coli pyelonephritis is described. Nine female pigs with a mean weight  of 19 kg were included in the study. Following laparotomy and ureterotomy, catheters were placed bilaterally  in the renal pelvis. A culture of a porcine E. coli strain (109 CFU/mL, volume 3.25 mL) was inoculated  unilaterally in the renal pelvis. Following bacterial inoculation, the catheter was occluded for 20 min. The  inoculation procedure was repeated after two and four hrs. The contralateral kidneys served as controls  and were inoculated with sterile saline. Six hrs after the first inoculation pigs were euthanized and samples  of blood, abdominal swabs, urine and specimens from kidney, liver and spleen were cultured. The inflammatory  response in the kidneys, renal lymph nodes, liver and spleen was evaluated both macroscopically  and histologically and E. coli was identified by immunohistochemistry. E. coli was reisolated from all the  inoculated kidneys and was detected immunohistochemically in all inoculated kidneys, in four renal lymph  nodes from inoculated sides and in four spleens. Evidence of systemic bacterial spread was observed in five  pigs. Gross and histological lesions of acute pyelonephritis comparable to human cases were demonstrated  in all but one inoculated kidney. In conclusion, a novel porcine model for evaluating the pathogenesis of  acute pyelonephritis was established.