1. Pediatric Oncology and Hematology Unit “Lalla Seràgnoli,” Pediatric Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy;
2. Unit of Microbial Ecology of Health, Department of Pharmacy and Biotechnology, and
3. Department of Medical and Surgical Sciences (DIMEC), University of Bologna, Bologna, Italy; and
4. Pediatric Clinic, Pietro Barilla Children's Hospital, University of Parma, Parma, Italy