1 St George's University NHS Foundation Trust, London, UK; Antimicrobial Pharmacodynamics and Therapeutics, Department of Molecular and Clinical Pharmacology, University of Liverpool, Liverpool, L69 3GE, UK; National Institute for Health Research, Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance, Imperial College London, London, UK. Electronic address: s.e.boyd@liverpool.ac.uk.
2 Centre of Defence Pathology, Royal Centre for Defence Medicine, Queen Elizabeth Hospital, Birmingham, UK; Chelsea and Westminster NHS Foundation Trust, London, UK.
3 National Institute for Health Research, Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance, Imperial College London, London, UK; Chelsea and Westminster NHS Foundation Trust, London, UK; North West London Pathology, Imperial College Healthcare NHS Trust, London, UK.