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Genome Biol. 2015 Apr 23;16:81. doi: 10.1186/s13059-015-0643-z.

Evolutionary dynamics of methicillin-resistant Staphylococcus aureus within a healthcare system.

Author information

1
National University Health System, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore. liyang_hsu@yahoo.com.
2
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. liyang_hsu@yahoo.com.
3
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. sh16@sanger.ac.uk.
4
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. monikachlebowicz@gmail.com.
5
University of Groningen, Hanzeplein 1, PO Box 30001, Groningen, 9700 RB, The Netherlands. monikachlebowicz@gmail.com.
6
Institute of Infection and Immunity, St George's, University of London, Cranmer Terrace, London, SW17 0RE, UK. jlindsay@sgul.ac.uk.
7
Singapore General Hospital, Outram Road, Singapore, 169608, Singapore. koh.tse.hsien@sgh.com.sg.
8
Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore. prabha_krishnan@ttsh.com.sg.
9
Changi General Hospital, 2 Simei Street 3, Singapore, 529889, Singapore. thean_yen_tan@cgh.com.sg.
10
National University Health System, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore. peiyunhon@gmail.com.
11
Curtin University of Technology, GPO Box U1987, Perth, WA, 6845, Australia. W.Grubb@curtin.edu.au.
12
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. sdb@sangera.ac.uk.
13
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. parkhill@sanger.ac.uk.
14
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. sjp97@medschl.cam.ac.uk.
15
University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 0QQ, UK. sjp97@medschl.cam.ac.uk.
16
The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 15A, UK. mtgh@st-andrews.ac.uk.
17
School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK. mtgh@st-andrews.ac.uk.

Abstract

BACKGROUND:

In the past decade, several countries have seen gradual replacement of endemic multi-resistant healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) with clones that are more susceptible to antibiotic treatment. One example is Singapore, where MRSA ST239, the dominant clone since molecular profiling of MRSA began in the mid-1980s, has been replaced by ST22 isolates belonging to EMRSA-15, a recently emerged pandemic lineage originating from Europe.

RESULTS:

We investigated the population structure of MRSA in Singaporean hospitals spanning three decades, using whole genome sequencing. Applying Bayesian phylogenetic methods we report that prior to the introduction of ST22, the ST239 MRSA population in Singapore originated from multiple introductions from the surrounding region; it was frequently transferred within the healthcare system resulting in a heterogeneous hospital population. Following the introduction of ST22 around the beginning of the millennium, this clone spread rapidly through Singaporean hospitals, supplanting the endemic ST239 population. Coalescent analysis revealed that although the genetic diversity of ST239 initially decreased as ST22 became more dominant, from 2007 onwards the genetic diversity of ST239 began to increase once more, which was not associated with the emergence of a sub-clone of ST239. Comparative genomic analysis of the accessory genome of the extant ST239 population identified that the Arginine Catabolic Mobile Element arose multiple times, thereby introducing genes associated with enhanced skin colonization into this population.

CONCLUSIONS:

Our results clearly demonstrate that, alongside clinical practice and antibiotic usage, competition between clones also has an important role in driving the evolution of nosocomial pathogen populations.

PMID:
25903077
PMCID:
PMC4407387
DOI:
10.1186/s13059-015-0643-z
[Indexed for MEDLINE]
Free PMC Article

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