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Mortality rates amongst mice with endogenous septicaemia caused by Pseudomonas aeruginosa isolates from various
N Furuya1, Y Hirakata, K Tomono
1Department of Laboratory Medicine, Nagasaki University School of Medicine, Japan.
Abstract:
Mice that had been treated with cyclophosphamide and ampicillin were fed with Pseudomonas aeruginosa. These procedures induced an endogenous septicaemia under conditions mimicking the pathophysiology of the disease in man. This model was used to compare the mortality rates in mice infected with P. aeruginosa isolates from various clinical sources. Mortality rates in mice given isolates from blood cultures had a broad range (0-100%), but the mean rate was significantly higher than with isolates from other infection sites. Moreover, blood isolates persisted in the intestines of mice after oral inoculation, whereas most isolates from other sources were gradually eliminated. Most P. aeruginosa isolates from blood culture produced significantly higher levels of exotoxin A and total proteases than isolates from other infection sites. Amongst the blood isolates, all but one of the lethal strains produced large quantities of exotoxin A or total proteases or both. Taken together, the results suggest that the ability of P. aeruginosa to adhere to the intestinal tract and to produce high levels of exo-enzymes may contribute to the development of fatal septicaemia.
Insights
Pseudomonas aeruginosa isolates from blood cultures caused higher mortality in mice, likely due to increased toxin production and intestinal persistence. This highlights key factors in developing fatal Pseudomonas aeruginosa sepsis.
Area of Science:
- Microbiology
- Infectious Diseases
- Pathophysiology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections.
- Understanding factors contributing to P. aeruginosa sepsis is crucial for clinical management.
Purpose of the Study:
- To investigate the virulence of P. aeruginosa isolates from different clinical sources.
- To identify characteristics associated with mortality in a murine model of P. aeruginosa sepsis.
Main Methods:
- A murine model of sepsis was established using cyclophosphamide and ampicillin treatment.
- Mice were orally inoculated with P. aeruginosa isolates from various human infection sites.
- Mortality rates, intestinal persistence, exotoxin A, and protease production were assessed.
Main Results:
- Isolates from blood cultures induced significantly higher mortality compared to those from other sites.
- Blood isolates demonstrated greater intestinal persistence and higher production of exotoxin A and proteases.
- Lethal blood isolates were strongly associated with high levels of exotoxin A and/or proteases.
Conclusions:
- P. aeruginosa's ability to adhere to the gut and produce exo-enzymes contributes to fatal sepsis.
- Isolates from blood cultures possess enhanced virulence factors potentially leading to severe disease.