[1] Karolinska Univ Hosp, Dept Pediat Surg, SE-17176 Stockholm, Sweden
[2] Karolinska Inst, Dept Womens & Childrens Hlth, Unit Pediat Surg, Stockholm, Sweden
[3] Karolinska Univ Hosp, Dept Clin Microbiol, SE-17176 Stockholm, Sweden
[4] Karolinska Univ Hosp, Dept Med Phys, SE-17176 Stockholm, Sweden
[5] Karolinska Inst, Dept Womens & Childrens Hlth, Childhood Canc Res Unit, Stockholm, Sweden