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Experimental endocarditis induction and platelet aggregation by Streptococcus anginosus, Streptococcus constellatus
1Department of Preventive Dentistry, Kagoshima University Dental School, Japan.
Abstract:
A total of 18 'Streptococcus milleri' strains including the ATCC type strains of Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius were compared with Streptococcus oralis ATCC10557 for their ability to induce infective endocarditis in catheterized rats. Three days after intravenous injection of 10(8) colony-forming units all 8 S. anginosus strains tested produced infective vegetations and bacteremia in almost all rats whereas 5 S. constellatus strains and the S. oralis strain produced infective vegetations and bacteremia less frequently and 5 S. intermedius strains only occasionally. The vegetations infected with the S. anginosus strains harbored microbial cells in significantly higher numbers that those with the other strains. No strong correlation was found between the endocardial infectivity and platelet-aggregating capacity of these strains. The platelet-aggregating strains were members of the Lancefield groups F and G or ungroupable but not of group A or C.
Insights
Streptococcus anginosus strains are more likely to cause infective endocarditis and bacteremia in rats than other Streptococcus milleri group species. This suggests S. anginosus may be a more significant pathogen in endocarditis.
Area of Science:
- Microbiology
- Infectious Diseases
- Cardiovascular Research
Background:
- The Streptococcus milleri group comprises several species, including Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius, known to cause various infections.
- Infective endocarditis is a serious infection of the heart valves, often caused by bacteria.
- Understanding the specific pathogenic potential of different Streptococcus species is crucial for effective treatment and prevention.
Purpose of the Study:
- To compare the ability of different Streptococcus milleri group strains to induce infective endocarditis in a rat model.
- To investigate the correlation between bacterial load in vegetations and infectivity.
- To explore the relationship between platelet aggregation and endocardial infectivity.
Main Methods:
- Comparison of 18 Streptococcus milleri group strains, including type strains of S. anginosus, S. constellatus, and S. intermedius, against Streptococcus oralis.
- Induction of infective endocarditis in catheterized rats via intravenous injection of 10(8) colony-forming units.
- Assessment of vegetation formation, bacteremia, and microbial cell numbers in vegetations.
Main Results:
- All 8 tested S. anginosus strains induced infective vegetations and bacteremia in nearly all rats.
- S. constellatus and S. oralis strains showed lower frequencies of inducing vegetations and bacteremia.
- S. intermedius strains only occasionally caused infective endocarditis, and microbial cell numbers were highest in S. anginosus-infected vegetations.
Conclusions:
- Streptococcus anginosus demonstrates a significantly higher capacity to induce infective endocarditis and bacteremia compared to other Streptococcus milleri group species tested.
- No strong correlation was observed between the infective potential and platelet-aggregating capacity of these strains.
- Further research may elucidate specific virulence factors contributing to S. anginosus's pathogenicity in endocarditis.