Evolution of Streptococcus pneumoniae and Its Close Commensal Relatives
Author Information
Author(s): Kilian Mogens, Poulsen Knud, Blomqvist Trinelise, Håvarstein Leiv S., Bek-Thomsen Malene, Tettelin Hervé, Sørensen Uffe B. S.
Primary Institution: Institute of Medical Microbiology and Immunology, Aarhus University
Hypothesis
The study aims to investigate the evolutionary history of the pneumococcus and its close commensal relatives using a polyphasic phylogenetic strategy.
Conclusion
The study suggests that Streptococcus pneumoniae evolved from a common ancestor with commensal streptococci, with significant gene loss leading to its pathogenic potential.
Supporting Evidence
- Phylogenetic analysis revealed a distinct clustering of S. pneumoniae and its close relatives.
- Random distribution of virulence genes among S. mitis lineages was observed.
- Genome size analysis indicated a reduction in S. mitis compared to S. pneumoniae.
Takeaway
Scientists studied how a germ called Streptococcus pneumoniae changed over time from being a harmful germ to a friendlier one, showing that some germs can lose their bad traits.
Methodology
The study used phylogenetic analysis based on 16S rRNA sequences and housekeeping genes from 118 strains of streptococci.
Potential Biases
Potential bias may arise from overrepresentation of disease-associated strains compared to commensal strains.
Limitations
The study's findings are based on a limited number of strains and may not represent all lineages of Streptococcus.
Participant Demographics
The strains included isolates from healthy individuals and clinical microbiology laboratories, with some from Japanese individuals and others from Caucasians.
Statistical Information
P-Value
p<0.0001
Statistical Significance
p<0.0001
Digital Object Identifier (DOI)
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