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[Ultrastructural changes in Pseudomonas aeruginosa cells as affected by gentamycin in in vitro and in vivo
Abstract:
Morphological changes in phagocytosed cells of Pseudomonas aeruginosa under the effect of gentamicin were studied with electron microscopy using ultrathin slices. Peritoneal macrophages induced by irritation of the peritoneum with medium 199 followed by inoculation with a 1-milliard suspension of Pseudomonas aeruginosa were used. Gentamicin was administered intramuscularly in single doses of 10, 20 and 50 mg/kg. The effect of gentamicin was also studied in vitro. The in vitro studies showed that gentamicin induced rarefaction of the cytoplasm in Pseudomonas aeruginosa, elimination of the nuclear material, formation of membrane structures and separation of the cytoplasmic membrane from the cell wall. The studies with exposure of phagocytosed bacteria to gentamicin showed that the phagocytosed bacterial cells had the most pronounced changes in their ultrastructure. Under the effect of gentamicin in a dose of 50 mg/kg there appeared 2 types of the cells with changes not observed in vitro. Investigation of the digestive capacity of phagocytes demonstrated that gentamicin favoured an increase in the phagocytic activity and digestive capacity.
Insights
Gentamicin causes significant ultrastructural changes in Pseudomonas aeruginosa, particularly within phagocytosed cells. This antibiotic enhances macrophage phagocytic and digestive activity, offering a potential therapeutic advantage.
Area of Science:
- Microbiology
- Cell Biology
- Pharmacology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Gentamicin is an aminoglycoside antibiotic used to treat bacterial infections.
- Understanding gentamicin's effects on bacterial morphology and host immune cells is crucial for optimizing treatment strategies.
Purpose of the Study:
- To investigate the morphological alterations in Pseudomonas aeruginosa cells induced by gentamicin.
- To examine the impact of gentamicin on phagocytosed bacteria within macrophages.
- To assess the effect of gentamicin on macrophage phagocytic and digestive capacities.
Main Methods:
- Electron microscopy was employed to study ultrathin slices of Pseudomonas aeruginosa.
- Peritoneal macrophages were induced and infected with Pseudomonas aeruginosa.
- Gentamicin was administered both in vivo (intramuscularly) and in vitro at varying doses (10, 20, 50 mg/kg).
Main Results:
- In vitro, gentamicin caused cytoplasmic rarefaction, nuclear material elimination, membrane structure formation, and cell wall separation in Pseudomonas aeruginosa.
- Phagocytosed Pseudomonas aeruginosa exhibited more pronounced ultrastructural changes compared to in vitro exposure.
- A dose of 50 mg/kg gentamicin induced unique cellular changes in phagocytosed bacteria not observed in vitro.
- Gentamicin treatment led to an increase in both phagocytic activity and digestive capacity of macrophages.
Conclusions:
- Gentamicin induces significant morphological damage to Pseudomonas aeruginosa, especially within macrophages.
- The antibiotic enhances the host's immune response by boosting macrophage activity.
- These findings suggest gentamicin's dual action on bacteria and host immune cells contributes to its efficacy.