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Chronic pyelonephritis. Electron microscopic study. II. Persistence of variant bacterial forms
Investigative Urology
|September 1, 1978
Summary
In immunosuppressed primates, Escherichia coli caused pyelonephritis, with bacteria persisting for 18 days. Electron microscopy revealed bacterial reorganization and cell-wall-less forms, highlighting immune system challenges in clearing kidney infections.
Area of Science:
- Nephrology
- Microbiology
- Immunology
Background:
- Ascending pyelonephritis is a significant kidney infection.
- Understanding bacterial persistence in the kidney is crucial for treatment.
- The role of the immune system in clearing renal infections requires further elucidation.
Purpose of the Study:
- To investigate the morphological changes of Escherichia coli during pyelonephritis in immunosuppressed nonhuman primates.
- To compare the development of pyelonephritis in immunocompetent versus immunosuppressed rhesus monkeys.
- To examine bacterial survival and host-pathogen interactions in the renal environment.
Main Methods:
- Induction of ascending nonobstructive pyelonephritis in female rhesus monkeys (Macaca mulatta) via ureteral catheterization with Escherichia coli (O4:H1).
- Immunosuppression of animals using cyclophosphamide.
- Examination of kidney tissue using electron microscopy to compare infected immunocompetent and immunosuppressed groups.
Main Results:
- Gross pyelonephritic scarring was observed in all immunosuppressed animals.
- Electron microscopy revealed bacterial reorganization into small dense bodies within bacteria and macrophages in immunosuppressed monkeys.
- Protoplast-like, cell wall-less bacterial forms were observed in the renal interstitium, with some containing internal particles.
- Electron-dense bodies were also found within subendothelial spaces of glomerular capillaries.
- Classical bacterial organisms persisted in the kidneys of partially immunoincompetent nonhuman primates for up to 18 days.
Conclusions:
- Morphological evidence confirms that Escherichia coli can cause pyelonephritis and persist for extended periods in immunosuppressed nonhuman primates.
- The study demonstrates the presence of unusual bacterial forms, including cell-wall-less variants, during infection.
- Observations suggest challenges faced by the host immune system, specifically leukocytes, in clearing intrarenal bacteria, raising questions about host-pathogen dynamics in chronic renal infections.