Electron microscopic study of acute retrograde pyelonephritis in mice
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T Deguchi1, M Kuriyama, S Maeda
1Department of Urology, Gifu University School of Medicine, Japan.
Abstract:
A strain of Escherichia coli O6:H-, which was isolated from a patient with acute pyelonephritis, was used to produce ascending pyelonephritis in mice. The histologic features at the early stage of acute pyelonephritis and the pathways of bacterial invasion and distribution in the infected kidneys were studied by using transmission electron microscope. The histologic changes were characterized by degeneration and destruction of renal pelvic and tubular epithelial cells, and a massive infiltration of polymorphonuclear leukocytes. Bacteria invaded the pelvic surface and spread over the renal medulla and cortex by contiguity twelve hours after infection. It was also shown that bacteria ascended the tubules, multiplied in the tubular lumina, destroyed the tubular epithelial cells, and spread over the renal cortex by twelve hours. In addition, bacteria and leukocytes phagocytizing bacteria were present in the capillaries in the renal interstitium twelve hours after infection.
Insights
This study reveals how Escherichia coli causes acute pyelonephritis in mice, detailing bacterial invasion and kidney damage. It highlights early-stage kidney infection mechanisms and cellular destruction.
Area of Science:
- Nephrology
- Microbiology
- Pathology
Background:
- Acute pyelonephritis is a significant kidney infection.
- Escherichia coli is a common causative agent of urinary tract infections, including pyelonephritis.
Purpose of the Study:
- To investigate the early histologic features of acute pyelonephritis.
- To elucidate the pathways of bacterial invasion and distribution in infected kidneys using a mouse model.
Main Methods:
- Utilizing a mouse model of ascending pyelonephritis induced by Escherichia coli O6:H-.
- Employing transmission electron microscopy to examine kidney tissue.
Main Results:
- Observed degeneration and destruction of renal pelvic and tubular epithelial cells.
- Documented massive infiltration of polymorphonuclear leukocytes.
- Demonstrated bacterial invasion of the pelvic surface, spreading via contiguity to medulla and cortex within 12 hours.
- Showed bacterial ascent through tubules, multiplication, tubular destruction, and cortical spread within 12 hours.
- Identified bacteria and phagocytizing leukocytes in renal interstitial capillaries within 12 hours.
Conclusions:
- Escherichia coli rapidly invades and disseminates within the kidney, causing significant tubular damage.
- Early-stage pyelonephritis involves epithelial cell destruction and inflammatory cell infiltration.
- The study provides detailed ultrastructural insights into the pathogenesis of bacterial kidney infections.