1. 1Department of Respiratory Medicine, Peterborough and Stamford Hospitals NHS Foundation Trust, Peterborough City Hospital, Bretton Gate, Peterborough, PE3 9GZ, UK
2. 2Snowdon Neurorehabilitation Unit, Western Community Hospital Solent NHS Trust, William Macleod Way, Southampton, SO16 4XE, UK
3. 3Clinical Microbiology and Public Health Laboratory, National Infection Service, Public Health England, Addenbrookes Hospital, Cambridge, CB2 2QW, UK
4. 4Department of Trauma and Orthopaedic Surgery, Peterborough and Stamford Hospitals NHS Foundation Trust, Peterborough City Hospital, Bretton Gate, Peterborough, PE3 9GZ, UK