[1] Alfa Inst Biomed Sci, Athens 15123, Greece
[2] PA Kyriakou Childrens Hosp, Pediat Intens Care Unit, Athens, Greece
[3] Henry Dunant Hosp, Dept Med, Athens, Greece
[4] Tufts Univ, Sch Med, Dept Med, Boston, MA 02111 USA
[5] PA Kyriakou Childrens Hosp, Dept Microbiol, Athens, Greece
[6] Univ Athens, P&A Kyriakou Childrens Hosp, Dept Pediat 2, Athens, Greece