1. Department of Medical microbiology, St. Olavs University Hospital, Trondheim, Norway
2. Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway
3. Department of Infectious Diseases Control, Municipality of Trondheim, Norway
4. Department of Infectious Diseases, St. Olavs University Hospital, Trondheim, Norway
5. Sørbyen Legesenter, Heimdal, Norway
6. Division of Infectious Disease Control, Norwegian Institute of Public Health, Oslo, Norway