[1] Univ Turin, Regina Margherita Childrens Hosp, Dept Pediat, Infect Dis Unit, I-10126 Turin, Italy
[2] Regina Margherita Childrens Hosp, Pediat Oncohematol Stem Cell Transplantat & Cellu, Turin, Italy
[3] Regina Margherita Childrens Hosp, Dept Bacteriol, Turin, Italy
[4] St Anna Hosp, Turin, Italy