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
Packer S1, Pichon B2, Thompson S3, Neale J4, Njoroge J5, Kwiatkowska RM6,1, Oliver I6,1, Telfer M4, Doumith M7,8,2, Buunaaisie C9, Heinsbroek E5, Hopewell-Kelly N9, Desai M5, Hope V10,5, Williams OM3, Kearns A11,2, Hickman M11,12,6, Gobin M11,1
1 Field Epidemiology Service, Public Health England, Bristol, United Kingdom.
2 Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, National Infection Service, Public Health England, London, United Kingdom.
3 Public health laboratory Bristol, Public Health England, Bristol, United Kingdom.
4 Bristol Drugs Project, Bristol, United Kingdom.
5 Blood Borne Virus Section, HIV & STI Department, National Infection Service, Public Health England, London, United Kingdom.
6 NIHR Health Protection Research Unit in Evaluation of Interventions at University of Bristol, Bristol, United Kingdom.
7 King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
8 Infectious Diseases Research Department, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia.
9 University of West England, Bristol, United Kingdom.
10 Public Health Institute, Liverpool John Moores University, Liverpool, United Kingdom.
11 Authors contributed equally to the work and share last authorship.
12 School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Year of Publication:
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).
We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak.
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.
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.
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.