[1] Hadassah Hebrew Univ, Med Ctr, Dept Pediat, Jerusalem, Israel
[2] Hadassah Hebrew Univ, Med Ctr, CF Ctr, Jerusalem, Israel
[3] Univ Milan, Dept Clin Sci & Community Hlth, Lab Med Stat Biometry & Epidemiol GA Maccacaro, Milan, Italy
[4] Charles Univ Prague, Motol Univ Hosp, Dept Med Microbiol, Prague, Czech Republic
[5] Charles Univ Prague, Motol Univ Hosp, Fac Med 2, Prague CF Ctr, Prague, Czech Republic