Related Experiment Videos
Experimental pneumonia produced by clinical isolates of Pseudomonas cepacia in mice
Y Yamagishi1, J Fujita, K Takigawa
1First Department of Internal Medicine, Kagawa Medical School.
Abstract:
An experimental Pseudomonas cepacia lung infection was induced in ddY mice pretreated with cyclophosphamide. A single dose of 250 mg of cyclophosphamide per kg resulted in leukopenia which lasted for four days. At the lowest PMN levels, the mice were exposed to various doses of bacteria by either intratracheal inoculation or aerosol inhalation. Experimental pneumonia was established by intratracheal inoculation of 1 x 10(7) - 2 x 10(8) colony-forming units of P. cepacia. The duration of survival time of the mice and the number of viable bacteria in their lungs were determined. A dramatic rise in the viable counts of P. cepacia was found within 24 hours after intratracheal inoculation of 1 x 10(8) colony-forming units of P. cepacia. It was impossible to establish P. cepacia pneumonia by aerosol inhalation, since the bacteria were immediately cleared from the lung. Mice which had not been treated with cyclophosphamide remained healthy and did not show any lung lesions. Thus, neutrophils appear to play an important role in the early defense mechanisms of the lung against P. cepacia. This animal model could be of use in evaluating additional therapies for the infection, and the pathologic determinants of infection caused by P. cepacia.
Insights
Neutrophils are crucial for early lung defense against Pseudomonas cepacia infection. This study establishes a mouse model for evaluating therapies against P. cepacia pneumonia.
Area of Science:
- Infectious Diseases
- Immunology
- Pulmonary Medicine
Background:
- Pseudomonas cepacia is an opportunistic pathogen causing severe lung infections, particularly in immunocompromised individuals.
- Neutrophils play a key role in the innate immune response against bacterial lung infections.
Purpose of the Study:
- To establish a reproducible murine model of Pseudomonas cepacia pneumonia.
- To investigate the role of neutrophils in the early host defense against P. cepacia lung infection.
- To provide a model for evaluating potential therapeutic interventions.
Main Methods:
- Cyclophosphamide was used to induce leukopenia in ddY mice, reducing neutrophil levels.
- Mice were infected with P. cepacia via intratracheal inoculation or aerosol inhalation.
- Bacterial counts in the lungs and survival times were monitored.
- Control mice received no cyclophosphamide treatment.
Main Results:
- Intratracheal inoculation with 1 x 10(7) - 2 x 10(8) colony-forming units of P. cepacia successfully established pneumonia in leukopenic mice.
- A rapid increase in viable P. cepacia was observed within 24 hours post-inoculation.
- Aerosol inhalation failed to establish infection, with bacteria being rapidly cleared.
- Non-leukopenic mice showed no lung lesions, indicating the importance of neutrophils.
Conclusions:
- Neutrophils are essential for the early defense against Pseudomonas cepacia in the lungs.
- The developed animal model is suitable for studying P. cepacia pathogenesis and testing new therapies.
- This model highlights the critical role of neutrophils in preventing P. cepacia pneumonia.