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Haemagglutinating activities of oral strains of Streptococcus milleri group
T Yamaguchi1, M Taketoshi, H Eifuku-Koreeda
1Department of Preventive Dentistry, Kagoshima University Dental School, Japan.
Abstract:
Of a total 148 strains of Streptococcus milleri group, 66 agglutinated sheep erythrocytes. The haemagglutinating strains were confined to serotypes g, h, i, j or were untypeable, and had no Lancefield group antigens (A to G and K), all of which have been shown to belong to Streptococcus intermedius. Cell surface hydrophobicity did not significantly differ even between the agglutinating and non-agglutinating S. intermedius strains. The haemagglutinating activity of strain 0813-1 (serotype i) was partially sensitive to heat (100 degrees C, 30 min) or trypsin (1 mg/ml, 30 min) treatment, but completely lost after the heat and subsequent trypsin treatments. Only L-arginine, L-lysine (100 mM), mucin, and fetuin (1 mg/ml) partially inhibited the haemagglutination with native bacterial cells but completely inhibited that with heated cells, whereas none was inhibitory in the reaction with trypsin-treated cells. The results suggest that at least two haemagglutinins are involved in the agglutination of the S. intermedius strain and that the heat-stable but trypsin-sensitive haemagglutinin recognizes the receptors on the erythrocyte surface which contain L-arginine and L-lysine at the reactive site.
Insights
Sixty-six Streptococcus intermedius strains agglutinated sheep red blood cells. Two distinct haemagglutinins were identified, with one heat-stable but trypsin-sensitive, recognizing L-arginine and L-lysine on erythrocyte surfaces.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Immunology
Background:
- The Streptococcus milleri group, including Streptococcus intermedius, are opportunistic pathogens.
- Haemagglutination by bacteria can be an important virulence factor, mediating adherence to host cells.
- Understanding the mechanisms of bacterial adherence is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the haemagglutinating properties of Streptococcus milleri group strains.
- To characterize the nature of the haemagglutinins involved in sheep erythrocyte agglutination by Streptococcus intermedius.
- To identify potential receptors on sheep erythrocytes recognized by these haemagglutinins.
Main Methods:
- Serotyping of 148 Streptococcus milleri group strains.
- Testing for sheep erythrocyte agglutination.
- Characterization of haemagglutinating activity using heat and trypsin treatments.
- Inhibition assays with various substances (amino acids, glycoproteins) to identify erythrocyte receptors.
Main Results:
- 66 out of 148 strains agglutinated sheep erythrocytes, primarily identified as Streptococcus intermedius.
- Haemagglutinating strains lacked Lancefield group antigens and belonged to specific serotypes (g, h, i, j) or were untypeable.
- Cell surface hydrophobicity did not differ significantly between agglutinating and non-agglutinating strains.
- Haemagglutinating activity was partially sensitive to heat and trypsin, with complete loss after sequential treatment.
- L-arginine, L-lysine, mucin, and fetuin inhibited haemagglutination, suggesting their role as erythrocyte receptors, particularly for the heat-stable haemagglutinin.
Conclusions:
- At least two haemagglutinins are involved in the agglutination of Streptococcus intermedius.
- A heat-stable, trypsin-sensitive haemagglutinin recognizes erythrocyte surface components containing L-arginine and L-lysine.
- These findings contribute to understanding the molecular mechanisms of Streptococcus intermedius adherence and potential virulence.