1. From the Department of Paediatrics, Allergology, Gastroenterology and Nutrition, Medical University of Lodz, Poland, Lodz
2. Department of Paediatrics, Allergology and Gastroenterology, Ludwik Rydygier Collegium Medicum Bydgoszcz, Nicolaus Copernicus University of Torun, Poland, Bydgoszcz