1. Department of Pediatric Oncology, Hematology and Transplantology, Poznan University of Medical Sciences, Poznan, Poland;
2. Department of Paediatric Haematology and Oncology, Medical University, Warszawa, Poland;
3. Department of Paediatric Haematology and Oncology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland;
4. Department of Microbiology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland;
5. Division of Paediatric Haematology and Oncology, Children Hospital, Olsztyn, Poland;
6. Department of Oncology, Children’s Memorial Health Institute, Warszawa, Poland;
7. Department of Microbiology, Children’s Memorial Health Institute, Warszawa, Poland;
8. Department of Pediatrics Hematology/Oncology and Gastroenterology, Pomeranian Medical University, Szczecin, Poland;
9. Department of Paediatric Oncology and Haematology, University Children’s Hospital, Jagiellonian University Collegium Medicum, Krakow, Poland;
10. University Children’s Hospital, Jagiellonian University Collegium Medicum, Krakow, Poland;
11. Department of Microbiology, Jagiellonian University Collegium Medicum, Krakow, Poland;
12. Department of Paediatrics, Haematology and Oncology, Medical University, Gdansk, Poland;
13. Department of Pediatric Haematology, Gdansk Medical University, Gdansk, Poland;
14. Division of Paediatric Haematology and Oncology, Children Hospital, Kielce, Poland;
15. Children Hospital, Kielce, Poland;
16. Department of Paediatric Oncology Haematology and Diabetology, Medical University, Lodz, Poland;
17. Department of Paediatric Oncology and Haematology, Medical University, Bialystok, Poland;
18. Division of Paediatric Oncology, Haematology and Chemotherapy, Department of Paediatric, Silesian Medical University, Katowice, Katowice, Poland;
19. Department of Pediatric Hematology and Oncology, Medical University of Silesia, Katowice, Zabrze, Poland;
20. Department of Pediatric Hematology and Oncology, Medical University of Silesia, Zabrze, Poland;
21. Division of Paediatric Haematology and Oncology, Chorzow Paediatric and Oncology Center, Chorzow, Poland;
22. Department of Pediatric Hematology and Oncology, Medical University, Lublin, Poland