1. Dept. of Paediatrics, Linköping University, Norrköping Hospital, SE-601 82 Norrköping, Sweden (fax. +46 11 223735, e-mail. lotta.hogberg@lio.se)
2. Dept. of Paediatrics, Norrköping Hospital and Linköping University Hospital, Linköping, Sweden
3. Dept. of Clinical Microbiology, Linköping University, Linköping, Sweden