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An ultrastructural study of the renal medulla in experimental acute pyelonephritis
Abstract:
Experimental acute pyelonephritis was produced in rats by a combination of intravenous administration of Escherichia coli, strain IMRU-54, and temporary unilateral mechanical ureteral obstruction. Structural alterations of the renal medulla were studied by light and electron microscopy. Major cellular alterations occurred in the vasa recta. Tubular and interstitial cells demonstrated minimal alterations after the brief period of acute inflammation. Polymorphonuclear leukocytes within tubular lumina contained structures resembling E. coli in nonprotoplasts-like form. Numerous protoplast-like organisms, to the exclusion of any other structural forms, were detected within the interstitium of the inner medulla. Nonprotoplast-like structures resembling E. coli were rarely observed in interstitium of the inner medulla. Following relief of ureteral obstruction, clearance of acute inflammation was rapid. In conclusion, hemoatogenous acute pyelonephritis induced by E. coli, IMRU-54, is able to inflict cytological and ultrastructural damage to structural elements of the inner and outer medulla of rats. Vasa recta incurred prominent alterations in endothelia and basement membranes, whereas tubular epithelia and interstitial cells had relatively good structural preservation. The data suggest that intravenously administered E. coli is capable to revert to a protoplast-like structure in the inner medulla.
Insights
Experimental pyelonephritis in rats showed Escherichia coli transforming into protoplast-like forms within the renal medulla. This study reveals structural damage to vasa recta, highlighting bacterial adaptation during infection.
Area of Science:
- Nephrology
- Microbiology
- Pathology
Background:
- Acute pyelonephritis is a serious kidney infection.
- Understanding Escherichia coli's behavior in the renal medulla is crucial for treatment.
Purpose of the Study:
- To investigate the structural alterations in rat renal medulla during experimental acute pyelonephritis.
- To examine the morphological changes of Escherichia coli within the kidney.
Main Methods:
- Induction of acute pyelonephritis in rats using Escherichia coli (strain IMRU-54) and ureteral obstruction.
- Analysis of renal medulla structure using light and electron microscopy.
Main Results:
- Escherichia coli adopted protoplast-like forms in the renal interstitium, particularly the inner medulla.
- Vasa recta exhibited significant endothelial and basement membrane damage.
- Tubular and interstitial cells showed minimal alterations.
Conclusions:
- Hematogenous acute pyelonephritis causes significant ultrastructural damage to the rat renal medulla.
- Escherichia coli can revert to protoplast-like structures in the inner medulla.
- Vasa recta are particularly vulnerable to damage during infection.