1. Institute of Medical Microbiology, Rikshospitalet-Radiumhospitalet Medical Center, Oslo
2. Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo
3. Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, and Department of Microbiology, St. Olavs Hospital, University Hospital of Trondheim, Trondheim
4. Department of Microbiology and Immunology, Haukeland University Hospital, Bergen
5. Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø
6. Department of Microbiology, Ullevål University Hospital, Oslo
7. University of Oslo, Oslo, Norway