1. Department of Clinical Microbiology, Nottingham University Hospitals NHS Trust, Queen's Medical Centre, Nottingham NG7 2UH, UK
2. Laboratory of HealthCare Associated Infection, Centre for Infections, Health Protection Agency, Colindale, London, UK
3. Institute of Infections, Immunity and Inflammation, School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK