1 Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK.
2 MRC Biostatistics Unit, School of Clinical Medicine, University of Cambridge, Cambridge, UK.
3 Infection Control, Cambridge University Hospitals, Cambridge, UK.
4 Department of Infectious Diseases, Cambridge University Hospitals, Cambridge, UK.
5 The John Farman ICU, Cambridge University Hospitals, Cambridge, UK; Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK.
6 Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK; Carnegie School of Sport, Headingley Campus, Leeds Beckett University, Leeds, UK.
7 Department of Microbiology, NHS Greater Glasgow and Clyde, Glasgow, UK.
8 Independent Consultant, City, University of London, London, UK.
9 Department of Medicine for the Elderly, Cambridge University Hospitals, Cambridge, UK; Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK. Electronic address: v.keevil@nhs.net.