1. Department of Clinical Medicine; Faculty of Medicine and Dentistry; University of Bergen; Bergen Norway
2. Department of Otolaryngology/Head and Neck Surgery; Haukeland University Hospital; Bergen Norway
3. Department of Pathology; Haukeland University Hospital; Bergen Norway
4. Department of Microbiology; Haukeland University Hospital; Bergen Norway
5. Department of Clinical Sciences; Faculty of Medicine and Dentistry; University of Bergen; Bergen Norway
6. Department of Otolaryngology/Head and Neck Surgery; Maastricht University Medical Centre; Maastricht The Netherlands