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Clonal expansion of community-associated meticillin-resistant Staphylococcus aureus (MRSA) in people who inject drugs (PWID): Prevalence, risk factors and molecular epidemiology, Bristol, United Kingdom, 2012 to 2017

Research output: Contribution to journalArticle

Original languageEnglish
Article number1800124
Issue number13
DateAccepted/In press - 28 Mar 2019
DatePublished (current) - 28 Mar 2019


Background: In 2015, Bristol (South West England) experienced a large increase in cases of meticillin-resistant Staphylococcus aureus (MRSA) infection in people who inject drugs (PWID).

Aim: We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak.

Methods: PWID recruited through an unlinked-anonymous community survey during 2016 completed behavioural questionnaires and were screened for MRSA. Univariable logistic regression examined associations with MRSA colonisation. Whole-genome sequencing used lineage-matched MRSA isolates, comparing PWID (screening and retrospective bacteraemia samples from 2012-2017) with non-PWID (Bristol screening) in Bristol and national reference laboratory database samples.

Results: The MRSA colonisation prevalence was 8.7% (13/149) and was associated with frequently injecting in public places (odds ratio (OR): 5.5; 95% confidence interval (CI):1.34–22.70), recent healthcare contact (OR: 4.3; 95% CI: 1.34–13.80) and injecting in groups of three or more (OR: 15.8; 95% CI: 2.51–99.28). People reporting any one of: injecting in public places, injection site skin and soft tissue infection or hospital contact accounted for 12/13 MRSA positive cases (sensitivity 92.3%; specificity 51.5%). Phylogenetic analysis identified a dominant clade associated with infection and colonisation among PWID in Bristol belonging to ST5-SCCmecIVg.

Conclusions: MRSA colonisation in Bristol PWID is substantially elevated compared with general population estimates and there is evidence of clonal expansion, community-based transmission and increased infection risk related to the colonising strain. Targeted interventions, including community screening and suppression therapy, education and basic infection control are needed to reduce MRSA infections in PWID.

    Research areas

  • Meticillin-Resistant Staphylococcus aureus, staphylococcal epidemiology, Staphylococcal Infections/transmission, MRSA, Sepsis, Injecting drug use, Intravenous, Substance Abuse, Intravenous: complications, Intravenous: microbiology, Drug users, Substance-Related Disorders/complications, Substance-Related Disorders/microbiology, Sequence Analysis, DNA, whole-genome sequencing, United Kingdom, community acquired infections, community acquired infections epidemiology, community acquired infections microbiology

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via EuroSurveillance at . Please refer to any applicable terms of use of the publisher.

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    Licence: CC BY


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