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Pathogenic properties of Edwardsiella species
J M Janda1, S L Abbott, S Kroske-Bystrom
1Microbial Diseases Laboratory, California Department of Health Services, Berkeley 94704-1011.
Abstract:
The pathogenic characteristics of 35 Edwardsiella strains from clinical and environmental sources were investigated. Overall, most Edwardsiella tarda strains were invasive in HEp-2 cell monolayers, produced a cell-associated hemolysin and siderophores, and bound Congo red; many strains also expressed mannose-resistant hemagglutination against guinea pig erythrocytes. Edwardsiella hoshinae strains bound Congo red and were variable in their invasive and hemolytic capabilities while Edwardsiella ictaluri strains did not produce either factor; neither E. hoshinae nor E. ictaluri expressed mannose-resistant hemagglutination nor elaborated siderophores under the tested conditions. Selected strains of each species tested for mouse lethality indicated strain variability in pathogenic potential, with E. tarda strains being the most virulent; 50% lethal doses in individual strains did not correlate with plasmid content, chemotactic motility, serum resistance, or expression of selected enzyme activities. The results suggest some potential important differences in pathogenic properties that may help explain their environmental distribution and ability to cause disease in humans.
Insights
This study investigated Edwardsiella strains, finding Edwardsiella tarda highly invasive and virulent. Differences in pathogenic traits among Edwardsiella species may explain their disease-causing potential and distribution.
Area of Science:
- Microbiology
- Pathogen Research
- Bacterial Pathogenesis
Background:
- Edwardsiella species are emerging pathogens with diverse clinical and environmental origins.
- Understanding the pathogenic mechanisms of Edwardsiella is crucial for disease control and prevention.
Purpose of the Study:
- To characterize the pathogenic properties of Edwardsiella tarda, Edwardsiella hoshinae, and Edwardsiella ictaluri strains.
- To compare the virulence factors and disease-causing potential across different Edwardsiella species.
Main Methods:
- In vitro assays for HEp-2 cell invasion, hemolysin production, siderophore elaboration, Congo red binding, and hemagglutination.
- In vivo mouse lethality studies to determine 50% lethal doses (LD50).
- Correlation analysis of virulence factors with plasmid content, motility, serum resistance, and enzyme activities.
Main Results:
- Edwardsiella tarda strains exhibited high invasiveness, hemolysin and siderophore production, and Congo red binding.
- Edwardsiella hoshinae showed variable invasiveness and hemolysis, while Edwardsiella ictaluri lacked these factors.
- Mouse lethality varied by strain, with E. tarda being most virulent; LD50 did not correlate with tested molecular or enzymatic factors.
Conclusions:
- Significant differences in pathogenic characteristics exist among Edwardsiella species.
- E. tarda possesses a more robust set of virulence factors contributing to its higher pathogenicity.
- These distinct pathogenic profiles may influence the environmental distribution and clinical impact of Edwardsiella infections.