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Virulence of different Pseudomonas species in a burned mouse model: tissue colonization by Pseudomonas cepacia
Abstract:
The virulence of Pseudomonas aeruginosa and other pseudomonads was examined in a burned mouse model. P. aeruginosa M-2 was highly virulent causing 100% mortality by 38 h with an injection of 10(2) CFU by either a subcutaneous or intraperitoneal route. Subcutaneous injection of 10(2) CFU revealed rapid multiplication of the bacteria at the burn wound with 10(8) CFU/g detectable in the burned skin by 28 h postinjection, 10(5) CFU/g of liver, and 10(3) CFU/ml of blood. Non-P. aeruginosa clinical isolates were markedly less virulent; an injection of greater than or equal to 10(7) CFU caused less than or equal to 60% lethality. P. cepacia SMH colonized the burned skin of thermally injured mice, persisting at levels of 10(7) to 10(8) CFU/g of burned skin after an initial injection of 10(5) CFU. P. cepacia persisted in the burn wound for at least 3 weeks. No organ invasion was detectable throughout this period. Studies with an additional clinical isolate of P. cepacia yielded similar results. An injection of a 10(2) CFU dose revealed that the level of persistence is dose dependent. Results suggest that the tenacious persistence of P. cepacia in the burn wound may provide a model for the study of persistent colonization and infection in a compromised host.
Insights
Pseudomonas aeruginosa is highly virulent in burned mice, causing rapid mortality. Pseudomonas cepacia colonizes burn wounds persistently without organ invasion, offering a model for studying chronic infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Wound Healing
Background:
- Burn wounds are susceptible to bacterial infections.
- Pseudomonas species are common nosocomial pathogens.
- Understanding virulence and persistence is crucial for treatment.
Purpose of the Study:
- To compare the virulence of Pseudomonas aeruginosa and other pseudomonads in a burned mouse model.
- To investigate the colonization and persistence of Pseudomonas cepacia in burn wounds.
- To establish a model for studying persistent bacterial colonization in compromised hosts.
Main Methods:
- Utilized a burned mouse model to assess bacterial virulence and colonization.
- Administered varying doses of Pseudomonas aeruginosa and Pseudomonas cepacia via subcutaneous or intraperitoneal injection.
- Quantified bacterial load in burn wounds, blood, and organs over time using colony-forming units (CFU).
Main Results:
- Pseudomonas aeruginosa M-2 demonstrated high virulence, causing 100% mortality at low doses (10^2 CFU).
- Pseudomonas cepacia SMH colonized burn wounds persistently (10^7-10^8 CFU/g) for over 3 weeks without organ invasion.
- Persistence of P. cepacia was found to be dose-dependent.
Conclusions:
- Pseudomonas aeruginosa poses a significant acute threat in burn infections.
- Pseudomonas cepacia exhibits tenacious persistence in burn wounds, suggesting its utility as a model for chronic infection studies.
- The burned mouse model effectively differentiates virulence and persistence characteristics of pseudomonads.