Abstract
*Hospital for Children and Adolescents, University of Helsinki, Stenbäckinkatu 11, FIN-00290 Helsinki, †Department of Bacteriology and Immunology, Haartman Institute, Haartmaninkatu 3, FIN-00290 Helsinki, ‡Laboratory Diagnostics, Helsinki University Central Hospital, Haartmaninkatu 3, FIN-00290 Helsinki, Department of Otorhinolaryngology, University of Helsinki, 00290 Helsinki, Finland and Professor- Hess-Children's Hospital, Bremen Central Hospital, 28205 Bremen, Germany
Corresponding author: Dr P. Lahdenne (e-mail: pekka.lahdenne{at}hus.fi ).