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Simple model for the study of Pseudomonas aeruginosa infections in leukopenic mice
Abstract:
A simple, reproducible model of fatal Pseudomonas aeruginosa sepsis in mice during immunosuppression was developed. Mice were rendered leukopenic (less than or equal to 800 leukocytes per mm3 of blood) for a period of 5 days by multiple injections of cyclophosphamide. Mice were challenged at the onset of leukopenia by instilling the bacteria onto a 0.5-mm incision made into the back. The mean lethal dose (LD50) for P. aeruginosa PA220 and M-2 was less than 20 bacteria. The mean time to death for these strains ranged from 46 to 59 h. Leukopenic mice were comparatively resistant when challenged with Klebsiella pneumoniae (LD50 = 1.5 x 10(6)) or Staphylococcus aureus (LD50 greater than 10(6)). Infection with P. aeruginosa was characterized by rapid bacterial multiplication in the skin at the site of infection, producing ecthyma gangrenosum. Bacteremia and colonization of the liver were pronounced 21 h postinfection. This model should prove to be a useful tool for studying the pathogenesis of P. aeruginosa infections under immunosuppressed conditions.
Insights
Researchers developed a reproducible mouse model for fatal Pseudomonas aeruginosa sepsis during immunosuppression. This model uses leukopenic mice and is crucial for studying P. aeruginosa pathogenesis.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections, particularly in immunocompromised individuals.
- Understanding P. aeruginosa pathogenesis requires reliable experimental models that mimic human conditions.
Purpose of the Study:
- To develop a simple, reproducible model of fatal Pseudomonas aeruginosa sepsis in immunosuppressed mice.
- To characterize the course of infection and determine lethal doses in the developed model.
Main Methods:
- Mice were rendered leukopenic using cyclophosphamide injections.
- Leukopenic mice were infected with P. aeruginosa via a skin incision.
- Bacterial load, mortality, and clinical signs were assessed.
Main Results:
- The lethal dose (LD50) for P. aeruginosa strains was less than 20 bacteria.
- Mean time to death ranged from 46 to 59 hours.
- Infection led to rapid bacterial multiplication, ecthyma gangrenosum, bacteremia, and liver colonization.
Conclusions:
- A reproducible mouse model for P. aeruginosa sepsis under immunosuppression was successfully established.
- The model demonstrates high susceptibility to P. aeruginosa but relative resistance to Klebsiella pneumoniae and Staphylococcus aureus.
- This model is valuable for investigating P. aeruginosa pathogenesis in immunocompromised states.