1. Unit of Microbiology, Department of Hematology and Oncology ‘L. and A. Seràgnoli’, University of Bologna, St Orsola Hospital, 40138 Bologna, Italy
2. Department of Preventive Pediatrics and Neonatology, University of Bologna, St Orsola Hospital, 40138 Bologna, Italy
3. Pediatric Oncology Hematology Unit, University of Bologna, St Orsola Hospital, 40138 Bologna, Italy