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Cross-reactions between pneumococci and other streptococci due to C polysaccharide and F antigen
1World Health Organization Collaborating Centre for Reference and Research on Pneumococci, Statens Seruminstitut, Copenhagen S, Denmark.
Abstract:
By serological methods, all 83 known types of Streptococcus pneumoniae could be shown to possess C polysaccharide and F antigen. Cross-reactions due to these two antigens between pneumococci and a broad range of most other commonly encountered streptococci were examined. The presence of an antigen closely similar or identical to pneumococcal C polysaccharide was demonstrated in some strains of Streptococcus mitior. Therefore, we conclude that pneumococci cannot be identified serologically from mixed samples without culture. Streptococcal group C antiserum was found to cross-react with pneumococcal F antigen.
Insights
Serological identification of Streptococcus pneumoniae is challenging due to cross-reactions. Pneumococci share C polysaccharide and F antigens with other streptococci, necessitating culture for accurate identification.
Area of Science:
- Microbiology
- Immunology
- Bacteriology
Background:
- Streptococcus pneumoniae is a significant human pathogen.
- Serological methods are commonly used for bacterial identification.
- Pneumococci possess specific antigens, including C polysaccharide and F antigen.
Purpose of the Study:
- To investigate serological cross-reactions between Streptococcus pneumoniae and other streptococci.
- To evaluate the utility of C polysaccharide and F antigen for pneumococcal identification.
- To determine the necessity of culture for accurate pneumococcal identification in mixed samples.
Main Methods:
- Serological testing was employed to analyze all 83 known types of Streptococcus pneumoniae.
- Cross-reactivity of C polysaccharide and F antigen was examined against a wide range of streptococcal strains.
- Antigenic similarity between pneumococci and Streptococcus mitior was specifically investigated.
Main Results:
- All 83 Streptococcus pneumoniae types possess C polysaccharide and F antigen.
- Cross-reactions were observed between pneumococcal antigens and other streptococci, notably Streptococcus mitior.
- Streptococcal group C antiserum cross-reacted with pneumococcal F antigen.
Conclusions:
- The presence of shared antigens (C polysaccharide, F antigen) complicates serological identification of pneumococci.
- Pneumococcal C polysaccharide antigen is also found in some Streptococcus mitior strains.
- Accurate serological identification of Streptococcus pneumoniae in mixed samples requires prior bacterial culture.