1. Department of Infectious Diseases, Danderyd Hospital, Danderyd, and Department of Clinical Microbiology, University Hospital, Linköping, Sweden
2. Department of Clinical Microbiology and Cancerepidemiology, University Hospital, Uppsala, Sweden
3. Department of Medico-Surgical Gastroenterology, University Hospital, Linköping, Sweden
4. Department of Clinical Microbiology, Danderyd Hospital, Danderyd, Sweden
5. Department of Clinical Microbiology, Karolinska Hospital, Stockholm, Sweden