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Pseudomonas aeruginosa exotoxin in mice: histopathology and serum enzyme changes
Abstract:
The histopathology and serum levels of mice inoculated intravenously with Pseudomonas aeruginosa exotoxin were studied. The toxin exerted a marked effect on the liver but elicited no demonstrable microscopic changes in other organs. The microscopic lesions caused in the liver by a single injection of two 50% lethal doses (LD50) of toxin (2.3 mug) were characterized by necrosis, cellular swelling, and fatty change within 4--8 hr and near total hepatocellular necrosis at 48 hr. Hepatic necrosis was accompanied by a parallel rise in serum levels of aspartate and alanine aminotransferases and alkaline phosphatase. A single injection of 10 LD50 elicited similar but somewhat more rapid degeneration. No progressive lesions were seen after injection of toxoid or of 0.5 LD50 of toxin.
Insights
Pseudomonas aeruginosa exotoxin primarily damages the liver in mice, causing hepatocellular necrosis and elevated liver enzymes. Lower doses or toxoid injections did not result in progressive liver injury.
Area of Science:
- Toxicology
- Hepatology
- Microbiology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Bacterial exotoxins can cause significant organ damage.
- Understanding exotoxin effects is crucial for treating infections.
Purpose of the Study:
- To investigate the effects of Pseudomonas aeruginosa exotoxin on mouse liver.
- To correlate histopathological changes with serum enzyme levels.
- To determine the dose-dependent toxicity of the exotoxin.
Main Methods:
- Intravenous inoculation of mice with varying doses of Pseudomonas aeruginosa exotoxin.
- Histopathological examination of liver and other organs.
- Measurement of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) levels.
Main Results:
- The exotoxin caused significant liver damage, including necrosis, cellular swelling, and fatty changes.
- Near-total hepatocellular necrosis was observed 48 hours after a single dose of 2 LD50.
- Serum levels of AST, ALT, and ALP increased in parallel with hepatic necrosis.
- Higher doses (10 LD50) caused more rapid degeneration.
- No progressive lesions were observed with toxoid or 0.5 LD50 of toxin.
Conclusions:
- Pseudomonas aeruginosa exotoxin is hepatotoxic in mice.
- The observed liver damage is dose-dependent.
- Serum liver enzymes serve as indicators of exotoxin-induced hepatic injury.