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Effect of calcium chloride on experimental infection of mice with Pseudomonas aeruginosa
Abstract:
Concomitant administration of Pseudomonas aeruginosa and calcium chloride to mice enhanced the virulence of some strains. The 50% lethal dose of P. aeruginosa 5 decreased by more than three orders of magnitude, regardless of the challenge route (intramuscular, subcutaneous, and intraperitoneal injection), while the 50% lethal dose of strain N10 did not decrease. When challenged intramuscularly with 10(4) organisms of strain 5 or strain N10 mixed with calcium chloride, both strains multiplied at the local site of injection. Strain 5 subsequently caused systemic infection, while strain N10 did not. The virulence-enhancing effect of calcium chloride can be successfully applied in protection assays for immunized mice challenged with strain 5.
Insights
Calcium chloride significantly enhances Pseudomonas aeruginosa virulence in mice for specific strains, lowering the lethal dose and aiding in protection assays. This finding is crucial for understanding bacterial pathogenesis and developing effective vaccines.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Bacterial virulence can be modulated by host factors or co-administered substances.
- Calcium chloride's role in modulating bacterial virulence is not fully understood.
Purpose of the Study:
- To investigate the effect of calcium chloride on the virulence of Pseudomonas aeruginosa in a murine model.
- To determine if calcium chloride enhances P. aeruginosa infectivity and lethality.
- To assess the utility of calcium chloride in challenge models for vaccine efficacy studies.
Main Methods:
- Mice were challenged with different strains of P. aeruginosa, with and without calcium chloride, via intramuscular, subcutaneous, and intraperitoneal routes.
- Bacterial load at the injection site and systemic infection were monitored.
- The 50% lethal dose (LD50) was determined for each condition.
- Protection assays were performed using immunized mice.
Main Results:
- Concomitant administration of calcium chloride significantly reduced the LD50 of P. aeruginosa strain 5 by over three orders of magnitude.
- The virulence-enhancing effect of calcium chloride was strain-dependent, with strain N10 showing no significant change in LD50.
- Both strains multiplied at the injection site when co-administered with calcium chloride.
- Strain 5 caused systemic infection, whereas strain N10 did not, following intramuscular challenge with calcium chloride.
- Calcium chloride facilitated protection assays for P. aeruginosa strain 5.
Conclusions:
- Calcium chloride acts as a virulence-enhancing factor for specific strains of Pseudomonas aeruginosa in mice.
- This effect is route-independent for susceptible strains.
- The enhanced virulence observed with calcium chloride can be leveraged to improve the sensitivity of challenge models for evaluating vaccine-induced protection against P. aeruginosa.