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Updated: Jan 26, 2026
Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
Competence in Streptococcus pneumoniae and Close Commensal Relatives: Mechanisms and Implications
Gabriela Salvadori1, Roger Junges1, Donald A Morrison2
1Faculty of Dentistry, Institute of Oral Biology, University of Oslo, Oslo, Norway.
Abstract:
The mitis group of streptococci comprises species that are common colonizers of the naso-oral-pharyngeal tract of humans. Streptococcus pneumoniae and Streptococcus mitis are close relatives and share ~60-80% of orthologous genes, but still present striking differences in pathogenic potential toward the human host. S. mitis has long been recognized as a reservoir of antibiotic resistance genes for S. pneumoniae, as well as a source for capsule polysaccharide variation, leading to resistance and vaccine escape. Both species share the ability to become naturally competent, and in this context, competence-associated killing mechanisms such as fratricide are thought to play an important role in interspecies gene exchange. Here, we explore the general mechanism of natural genetic transformation in the two species and touch upon the fundamental clinical and evolutionary implications of sharing similar competence, fratricide mechanisms, and a large fraction of their genomic DNA.
Insights
Streptococcus mitis and Streptococcus pneumoniae share genes and natural competence, facilitating gene exchange. Their similar mechanisms of competence and fratricide have significant clinical and evolutionary implications.
Area of Science:
- Microbiology
- Genetics
- Evolutionary Biology
Background:
- The mitis group of streptococci are common human colonizers.
- Streptococcus pneumoniae and Streptococcus mitis are closely related but differ in pathogenicity.
- S. mitis is a known reservoir for antibiotic resistance and vaccine escape mechanisms in S. pneumoniae.
Purpose of the Study:
- To explore the mechanism of natural genetic transformation in S. pneumoniae and S. mitis.
- To discuss the clinical and evolutionary implications of shared genetic exchange mechanisms between these species.
Main Methods:
- Comparative genomics to assess shared orthologous genes.
- Investigation of natural genetic transformation processes.
- Analysis of competence-associated killing mechanisms, including fratricide.
Main Results:
- S. pneumoniae and S. mitis share a significant proportion of orthologous genes (~60-80%).
- Both species exhibit natural competence, a key factor in genetic exchange.
- Similarities in competence and fratricide mechanisms facilitate interspecies gene transfer.
Conclusions:
- Shared genetic background and natural competence mechanisms drive interspecies gene exchange between S. pneumoniae and S. mitis.
- Understanding these mechanisms is crucial for addressing antibiotic resistance and vaccine development.
- The evolutionary relationship highlights the dynamic nature of bacterial adaptation and pathogenicity.
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