1. Department of Otorhinolaryngology, Wilhelmina Children's Hospital (Drs Aarts, Aardweg, Rovers, and Schilder), University Medical Center Utrecht, Utrecht, The Netherlands
2. Julius Center for Health Sciences and Primary Care (Drs Rovers, Bonten, and Schilder), University Medical Center Utrecht, Utrecht, The Netherlands
3. Department of Medical Microbiology (Dr Bonten), University Medical Center Utrecht, Utrecht, The Netherlands