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Distribution of presumptive pathogenicity factors among beta-hemolytic streptococci isolated from Ethiopia
1Department of Biology, University of Addis Ababa, Ethiopia.
Abstract:
Beta-hemolytic streptococci are known to bind several mammalian proteins, which are presumed to be important in pathogenicity. The distribution of such binding structures was examined for mouse albumin, human serum IgA, human IgG, human fibrinogen, and human plasminogen. A total of 218 group A beta-hemolytic streptococci (GAS) were studied: 5 isolates from children with acute rheumatic fever (ARF), 18 from acute post-streptococcal glomerulonephritis (APSGN), 57 from tonsillitis, 52 from skin infections, and 86 from healthy carriers. Sixty-eight Streptococcus equisimilis and 20 group G streptococci were also included. Most of the S. equisimilis (60/68) and group G (14/20) were obtained from apparently healthy carriers. The results were evaluated with respect to T type, serum opacity reaction (SOR), site of isolation, and disease type. No direct correlation was detected between the protein-binding structures studied. There was no apparent correlation between any particular protein-binding structure and specific T type. Albumin-binding and IgA-binding activities were inversely correlated among skin and nephritis GAS isolates. A strong correlation was demonstrated between IgA-binding activity and SOR production, while albumin-binding activity correlated with SOR-negative strains. Albumin-binding levels in isolates from ARF, APSGN and tonsillitis were significantly higher than in isolates from healthy carriers (P < 0.001). A higher albumin-binding capacity was shown in skin isolates from APSGN than in isolates from impetigo (P < 0.001).
Insights
Beta-hemolytic streptococci binding to mammalian proteins like albumin is linked to pathogenicity. Higher albumin binding in isolates from acute rheumatic fever and post-streptococcal glomerulonephritis suggests a role in disease development.
Area of Science:
- Microbiology
- Immunology
- Pathogenesis
Background:
- Beta-hemolytic streptococci possess surface proteins that bind mammalian proteins, potentially contributing to pathogenicity.
- Understanding the distribution of these binding structures is crucial for elucidating streptococcal virulence.
Purpose of the Study:
- To investigate the prevalence and correlation of mammalian protein-binding structures (albumin, IgA, IgG, fibrinogen, plasminogen) in various group A beta-hemolytic streptococci (GAS) isolates.
- To evaluate the relationship between protein-binding activities, T types, serum opacity reaction (SOR), and clinical manifestations.
Main Methods:
- Analysis of 218 GAS isolates from diverse clinical sources (rheumatic fever, glomerulonephritis, tonsillitis, skin infections, healthy carriers).
- Inclusion of Streptococcus equisimilis and group G streptococci isolates.
- Evaluation of protein-binding activities against mouse albumin, human IgA, IgG, fibrinogen, and plasminogen.
- Correlation analysis with T type, SOR, and site of isolation.
Main Results:
- No direct correlation was found between specific protein-binding structures and T types.
- Albumin-binding and IgA-binding activities showed an inverse correlation in skin and nephritis GAS isolates.
- A strong positive correlation existed between IgA-binding activity and SOR production.
- Albumin-binding activity correlated with SOR-negative strains.
- Significantly higher albumin-binding levels were observed in isolates from acute rheumatic fever, acute post-streptococcal glomerulonephritis, and tonsillitis compared to healthy carriers (P < 0.001).
- Skin isolates from acute post-streptococcal glomerulonephritis exhibited higher albumin-binding capacity than those from impetigo (P < 0.001).
Conclusions:
- Albumin-binding activity is significantly elevated in GAS isolates associated with inflammatory conditions like ARF, APSGN, and tonsillitis.
- The correlation between albumin binding and disease severity, particularly in APSGN skin isolates, warrants further investigation into its pathogenic role.