Science 24 November 2006:
Vol. 314. no. 5803, pp. 1301 - 1304
DOI: 10.1126/science.1134933

Reports
Evolutionary History of Salmonella Typhi
Philippe Roumagnac,1 François-Xavier Weill,2 Christiane Dolecek,3 Stephen Baker,4 Sylvain Brisse,2 Nguyen Tran Chinh,5 Thi Anh Hong Le,6 Camilo J. Acosta,7* Jeremy Farrar,3 Gordon Dougan,4 Mark Achtman1

For microbial pathogens, phylogeographic differentiation seems to be relatively common. However, the neutral population structure of Salmonella enterica serovar Typhi reflects the continued existence of ubiquitous haplotypes over millennia. In contrast, clinical use of fluoroquinolones has yielded at least 15 independent gyrA mutations within a decade and stimulated clonal expansion of haplotype H58 in Asia and Africa. Yet, antibiotic-sensitive strains and haplotypes other than H58 still persist despite selection for antibiotic resistance. Neutral evolution in Typhi appears to reflect the asymptomatic carrier state, and adaptive evolution depends on the rapid transmission of phenotypic changes through acute infections.

1 Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Charitéplatz 1, 10117 Berlin, Germany.
2 Institut Pasteur, Unité Biodiversité des Bactéries Pathogènes Emergentes, 28 rue du Docteur Roux, 75724 Paris cedex 15, France.
3 Oxford University Clinical Research Unit, Hospital for Tropical Diseases, 190 Ben Ham Tu, District 5, Ho Chi Minh City, Vietnam.
4 The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK.
5 Hospital for Tropical Diseases, 190 Ben Ham Tu, District 5, Ho Chi Minh City, Vietnam.
6 Institut National d'Hygiène et d'Épidémiologie, Hanoi 1000, Vietnam.
7 International Vaccine Institute (IVI), Kwanak Post Office Box 14, Seoul 151-600, Korea.

* Present address: GlaxoSmithKline, King of Prussia, PA 19406–2772, USA.

To whom correspondence should be addressed. E-mail: achtman@mpiib-berlin.mpg.de