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Published on: September 27, 2016
Evolutionary history of Salmonella typhi
Philippe Roumagnac1, François-Xavier Weill, Christiane Dolecek
1Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Charitéplatz 1, 10117 Berlin, Germany.
Science (New York, N.Y.)
|November 25, 2006
Summary
Salmonella Typhi evolution shows neutral changes from carriers and rapid spread of antibiotic resistance, like fluoroquinolones, through infections. Despite resistance, sensitive strains persist.
Area of Science:
- Microbiology
- Evolutionary Biology
- Population Genetics
Background:
- Phylogeographic differentiation is common in microbial pathogens.
- Salmonella enterica serovar Typhi (Typhi) exhibits a neutral population structure with persistent ubiquitous haplotypes.
- Antibiotic resistance, particularly fluoroquinolones, has driven rapid genetic changes in Typhi.
Purpose of the Study:
- To investigate the evolutionary dynamics of Salmonella Typhi.
- To understand the interplay between neutral evolution and adaptive selection in Typhi.
- To analyze the impact of antibiotic use on Typhi's population structure and haplotype distribution.
Main Methods:
- Phylogeographic analysis of Salmonella Typhi populations.
- Genomic analysis to identify mutations (e.g., gyrA mutations).
- Tracking the expansion of specific haplotypes (e.g., H58) in different geographical regions.
Main Results:
- Typhi's neutral population structure is shaped by long-term carrier states.
- Fluoroquinolone use led to rapid emergence of gyrA mutations and H58 haplotype expansion.
- Antibiotic-sensitive strains and non-H58 haplotypes persist despite selection pressures.
Conclusions:
- Neutral evolution in Typhi is linked to asymptomatic carriage.
- Adaptive evolution is driven by rapid transmission of traits during acute infections.
- Typhi's evolution is a complex interplay of neutral processes and strong selective pressures like antibiotic resistance.
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