1. Department of Medical Microbiology, Leiden University Medical Centre, Leiden, the Netherlands
2. National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
3. Institut für Hygiene und Umweltmedizin, Charité Universitätsmedizin Berlin, Berlin, Germany
4. National Institute for Health and Welfare (THL), Helsinki, Finland
5. Institute of Clinical Microbiology, University of Szeged, Szeged, Hungary
6. Istituto Superiore di Sanità, Rome, Italy
7. National Centre of Infectious and Parasitic Diseases, Sofia, Bulgaria
8. Health Protection Surveillance Centre and Beaumont Hospital, Dublin, Ireland
9. National Reference Laboratory for C. difficile, Paris, France
10. Public Health Wales, UK Anaerobe Reference Laboratory, Cardiff, United Kingdom
11. Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
12. European Centre for Disease Prevention and Control, Stockholm, Sweden