1. Nuffield Department of Primary Care Health Sciences, Radcliffe Primary Care Bldg, University of Oxford, Oxford, United Kingdom
2. Centre for Trials Research, Cardiff University, Heath Park, Cardiff, United Kingdom
3. Primary Care and Population Sciences Unit, University of Southampton, Aldermoor Health Centre, Aldermoor Close, Southampton, United Kingdom
4. Specialist Antimicrobial Chemotherapy Unit, Public Health Wales Microbiology, University Hospital of Wales, Heath Park, Cardiff, United Kingdom
5. NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust and University of Southampton, Southampton, United Kingdom
6. Division of Population Medicine, School of Medicine, Neuadd Meirionnydd, Cardiff University, Cardiff, United Kingdom