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Electronmicroscopy studies on the bactericidal action of inflammatory leukocytes in murine salmonellosis
Abstract:
Inbred female C3H mice were given 2 X 10(7) cfu virulent Salmonella typhimurium by intraperitoneal injection. Peritoneal washings were harvested between 3 h and 72 h after infection and examined by electronmicroscopy. There was evidence of intracellular killing by polymorphs and macrophages. The degeneration of intracellular salmonellae was seen initially as enlarging central electron-lucent areas in the cytoplasm and peripheral condensation of cytoplasmic granules, followed by disruption of the bacterial envelope and disintegration of cellular structure. Alternatively, the initial injury appeared as an irregular and discontinuous bacterial envelope with compression of the bacterium and diffuse condensation of cytoplasmic granules. It was also evident that virulent salmonellae multiplied extracellularly in the peritoneal cavity of the infected mice.
Insights
Electron microscopy revealed how immune cells like macrophages kill virulent Salmonella typhimurium within the peritoneal cavity. The study also observed extracellular bacterial multiplication in infected mice.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Salmonella typhimurium is a significant bacterial pathogen.
- Understanding host-pathogen interactions is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the ultrastructural changes of virulent Salmonella typhimurium during intracellular killing by host immune cells.
- To observe the extracellular behavior of Salmonella typhimurium in the peritoneal cavity.
Main Methods:
- Inbred female C3H mice were infected intraperitoneally with virulent Salmonella typhimurium.
- Peritoneal washings were collected at various time points (3-72 hours post-infection).
- Samples were examined using electron microscopy.
Main Results:
- Electron microscopy showed intracellular killing of Salmonella by polymorphs and macrophages.
- Degeneration of intracellular bacteria involved cytoplasmic changes and envelope disruption.
- Virulent Salmonella typhimurium also demonstrated extracellular multiplication within the peritoneal cavity.
Conclusions:
- Host immune cells effectively target and degrade intracellular Salmonella typhimurium.
- Extracellular proliferation of Salmonella typhimurium occurs in the peritoneal cavity, indicating a complex infection dynamic.