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Evolution of the community-onset invasive Staphylococcus argenteus ST2250 clone in northeast Thailand is linked with the acquisition of livestock-associated staphylococcal genes

Published version
Peer-reviewed

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Authors

Moradigaravand, D 
Blane, B 

Abstract

Staphylococcus argenteus is a newly named species previously described as a divergent lineage of Staphylococcus aureus that has recently been shown to have a global distribution. Despite growing evidence of the clinical importance of this species, knowledge about its population epidemiology and genomic architecture is limited. We used whole-genome sequencing to evaluate and compare S. aureus (n 251) and S. argenteus (n 68) isolates from adults with staphylococcal sepsis at several hospitals in northeastern Thailand between 2006 and 2013. The majority (82%) of the S. argenteus isolates were of multilocus sequence type 2250 (ST2250). S. aureus was more diverse, although 43% of the isolates belonged to ST121. Bayesian analysis suggested an S. argenteus ST2250 substitution rate of 4.66 (95% confidence interval [CI], 3.12 to 6.38) mutations per genome per year, which was comparable to the S. aureus ST121 substitution rate of 4.07 (95% CI, 2.61 to 5.55). S. argenteus ST2250 emerged in Thailand an estimated 15 years ago, which contrasts with the S. aureus ST1, ST88, and ST121 clades that emerged around 100 to 150 years ago. Comparison of S. argenteus ST2250 genomes from Thailand and a global collection indicated a single introduction into Thailand, followed by transmission to local and more distant countries in Southeast Asia and further afield. S. argenteus and S. aureus shared around half of their core gene repertoire, indicating a high level of divergence and providing strong support for their classification as separate species. Several gene clusters were present in ST2250 isolates but absent from the other S. argenteus and S. aureus study isolates. These included multiple exotoxins and antibiotic resistance genes that have been linked previously with livestock-associated S. aureus, consistent with a livestock reservoir for S. argenteus. These genes appeared to be associated with plasmids and mobile genetic elements and may have contributed to the biological success of ST2250.

Description

Keywords

genomic epidemiology, Staphylococcus argenteus, Staphylococcus aureus, antibiotic resistance

Journal Title

Microbial Genomics

Conference Name

Journal ISSN

2161-2129
2150-7511

Volume Title

8

Publisher

Microbiology Society
Sponsorship
Wellcome Trust (098600/Z/12/Z)
This publication presents independent research supported by the Health Innovation Challenge Fund (HICF-T5-342 and WT098600), a parallel funding partnership between the UK Department of Health and the Wellcome Trust. This project was also funded by a grant awarded to the Wellcome Trust Sanger Institute (098051). This study was also funded by a Wellcome Trust Career Development award in Public Health and Tropical Medicine (087769/Z/08/Z) to N.C.