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Exotoxin production by clinical isolates of pseudomonas aeruginosa
Abstract:
Seventy-five consecutive clinical Pseudomonas aeruginosa isolates were tested for in vitro exotoxin production. Exotoxin was demonstrated in culture filtrates biologically, by its ability to produce characteristic dermonecrotic lesions in guinea pigs, and seriologically, by counterimmunoelectrophoresis (CIE) with rabbit antiserum elicited with purified exotoxin. By these two methods, exotoxin was detected in 87 and 89% of P. aeruginosa strains, respectively (r = 0.48, P less than 0.001). Although less sensitive than CIE in detecting exotoxin immunodiffusion demonstrated a reaction of antigenic identity in most cases. Exotoxin was produced by all seven Fisher-Devlin immunotypes and by untypable strains. In contrast, exotoxin was not detected in the culture filtrates of 16 non-aeruginosa pseudomonas isolates and 48 non-pseudomonas organisms. The production of biologically similar antigenically closely related exotoxins is thus a characteristic of the majority of P. aeruginosa strains derived from diverse clinical sources.
Insights
Most clinical Pseudomonas aeruginosa strains produce exotoxins, confirmed by guinea pig skin tests and counterimmunoelectrophoresis. This exotoxin production is a common characteristic across diverse P. aeruginosa strains.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen frequently associated with infections.
- Exotoxin production is a key virulence factor in P. aeruginosa infections.
- Understanding exotoxin prevalence is crucial for diagnostics and therapeutics.
Purpose of the Study:
- To determine the prevalence of exotoxin production in clinical isolates of Pseudomonas aeruginosa.
- To compare biological and serological methods for exotoxin detection.
- To characterize the exotoxin produced by P. aeruginosa.
Main Methods:
- In vitro testing of 75 clinical P. aeruginosa isolates for exotoxin production.
- Biological assay using dermonecrotic lesions in guinea pigs.
- Serological assay using counterimmunoelectrophoresis (CIE) with specific rabbit antiserum.
- Immunodiffusion assay to assess antigenic identity.
Main Results:
- Exotoxin was detected in 87% of P. aeruginosa strains by biological assay and 89% by CIE.
- CIE demonstrated higher sensitivity in detecting exotoxin compared to immunodiffusion.
- Exotoxin was produced by all tested Fisher-Devlin immunotypes and untypable strains.
- No exotoxin was detected in non-aeruginosa Pseudomonas or non-Pseudomonas organisms.
Conclusions:
- The majority of clinical P. aeruginosa strains produce exotoxins.
- These exotoxins are biologically similar and antigenically related.
- Exotoxin production is a widespread characteristic of P. aeruginosa, regardless of immunotype.