Multi-locus sequence typing of Salmonella enterica serovar Typhimurium isolates from wild birds in northern England suggests host-adapted strain
Article first published online: 31 AUG 2010
© 2010 The Authors. Journal compilation © 2010 The Society for Applied Microbiology
Letters in Applied Microbiology
Volume 51, Issue 4, pages 477–479, October 2010
How to Cite
Hughes, L.A., Wigley, P., Bennett, M., Chantrey, J. and Williams, N. (2010), Multi-locus sequence typing of Salmonella enterica serovar Typhimurium isolates from wild birds in northern England suggests host-adapted strain. Letters in Applied Microbiology, 51: 477–479. doi: 10.1111/j.1472-765X.2010.02918.x
- Issue published online: 14 SEP 2010
- Article first published online: 31 AUG 2010
- Accepted manuscript online: 12 AUG 2010 12:00AM EST
- 2010/0324: received 24 February 2010, revised 29 July 2010 and accepted 29 July 2010
- host adaptation;
- molecular epidemiology;
- wild birds
Aims: Recent studies have suggested that Salmonella Typhimurium strains associated with mortality in UK garden birds are significantly different from strains that cause disease in humans and livestock and that wild bird strains may be host adapted. However, without further genomic characterization of these strains, it is not possible to determine whether they are host adapted. The aim of this study was to characterize a representative sample of Salm. Typhimurium strains detected in wild garden birds using multi-locus sequence typing (MLST) to investigate evolutionary relationships between them.
Methods and Results: Multi-locus sequence typing was performed on nine Salm. Typhimurium strains isolated from wild garden birds. Two sequence types were identified, the most common of which was ST568. Examination of the public Salmonella enterica MLST database revealed that only three other ST568 isolates had been cultured from a human in Scotland. Two further isolates of Salm. Typhimurium were determined to be ST19.
Conclusions: Results of MLST analysis suggest that there is a predominant strain of Salm. Typhimurium circulating among garden bird populations in the United Kingdom, which is rarely detected in other species, supporting the hypothesis that this strain is host adapted.
Significance and Impact of the Study: Host–pathogen evolution is often assumed to lead to pathogens becoming less virulent to avoid the death of their host; however, infection with ST568 led to high mortality rates among the wild birds examined, which were all found dead at wild bird-feeding stations. We hypothesize that by attracting unnaturally high densities of birds, wild bird-feeding stations may facilitate the transmission of ST568 between wild birds, therefore reducing the evolutionary cost of this pathogen killing its host, resulting in a host-adapted strain with increased virulence.