Affiliation: | From the Department of Otorhinolaryngology (Koskenkorva, Koivunen, Kristo, Alho), Institute of Clinical Medicine, University of Oulu and Oulu University Hospital; the Department of Medical Microbiology (Koskela), Oulu University Hospital, Oulu, Finland; and the Medical Research Unit (Niemela), Seinajoki Central Hospital and University of Tampere, Tampere, Finland |