Related Experiment Videos
[A study on the pathogenesis of Streptococcus mitis exotoxin]
Objective:
To study the isolation, purification and pathogenesis of Streptococcus mitis pyrogenic exotoxin causing toxic shock syndrome.
Methods:
Streptococcus mitis isolated from patients' throat were shaking cultivated. After being centrifuged, the supernatant fluid of the culture was precipitated with 20%, 40%, 60%, 80% (NH(4))(2)SO(4) respectively and the fast protein liquid chromatography(FPLC) was used for the final step of purification. Rabbits receiving subcutaneous injection with respective purified proteins were monitored daily for fever. The ability of the purified proteins to enhance the susceptibility of the rabbits to lethal Escherichia coli endotoxin shock is recorded, when the endotoxin was injected intravenously 4 hours after administration of 10 microg Streptococcus mitis exotoxin.
Results:
Only the protein precipitated by 20% (NH(4))(2)SO(4) (molecular weight is 34,000) from culture supernatant fluid was pyrogenic for rabbits (average temperature increase near 1 degrees C), and it can also cause the proliferation of rabbit splenocytes (mitogenicity). All the animals receiving subcutaneous injection of exotoxin containing purified proteins precipitated with higher concentrations of (NH(4))(2)SO(4) died within 16 approximately 29 hours after intravenous injection of the Escherichia coli endotoxin, demonstrating the enhanced susceptibility of the animals to lethal endotoxin shock. The control rabbits displayed none of these effects.
Conclusion:
Streptococcus mitis exotoxin is a novel streptococcal pyrogenic exotoxin.
Insights
A novel pyrogenic exotoxin from Streptococcus mitis was isolated and purified. This exotoxin causes fever and enhances susceptibility to lethal endotoxin shock in rabbits, identifying it as a potential cause of toxic shock syndrome.
Area of Science:
- Microbiology
- Immunology
- Toxicology
Context:
- Streptococcus mitis is a common bacterium found in the human throat.
- Toxic shock syndrome (TSS) is a severe, life-threatening condition.
- The role of specific exotoxins in TSS pathogenesis requires further elucidation.
Purpose:
- To isolate and purify the pyrogenic exotoxin produced by Streptococcus mitis.
- To characterize the pyrogenic and mitogenic properties of the purified exotoxin.
- To investigate the role of Streptococcus mitis exotoxin in enhancing susceptibility to lethal endotoxin shock.
Summary:
- Streptococcus mitis was cultured, and its supernatant was fractionated using ammonium sulfate precipitation and Fast Protein Liquid Chromatography (FPLC).
- The purified exotoxin (34,000 MW), precipitated at 20% ammonium sulfate, induced fever and splenocyte proliferation in rabbits.
- Animals treated with higher concentrations of purified exotoxin exhibited increased susceptibility to lethal Escherichia coli endotoxin shock.
Impact:
- Identifies a novel streptococcal pyrogenic exotoxin from Streptococcus mitis.
- Provides insights into the pathogenesis of toxic shock syndrome.
- Establishes a foundation for further research into Streptococcus-associated diseases.