[1] Childrens Hosp Philadelphia, Div Infect Dis, Philadelphia, PA 19104 USA
[2] Childrens Hosp Philadelphia, Ctr Pediat Clin Effectiveness, Philadelphia, PA 19104 USA
[3] Univ Penn, Dept Pediat, Perelman Sch Med, Philadelphia, PA 19104 USA
[4] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Philadelphia, PA 19104 USA
[5] Aristotle Univ Thessaloniki, Sch Hlth Sci, Dept Pediat 3, Infect Dis Unit, Thessaloniki, Greece
[6] Hippokrateion Hosp, Thessaloniki, Greece
[7] Baylor Coll Med, Dept Pediat, Infect Dis Sect, Houston, TX 77030 USA
[8] Texas Childrens Hosp, Houston, TX 77030 USA
[9] Univ Colorado, Sch Med, Boulder, CO 80309 USA
[10] Childrens Hosp Colorado, Aurora, CO USA
[11] Univ Southern Calif, Keck Sch Med, Childrens Hosp Los Angeles, Los Angeles, CA USA
[12] All Childrens Hosp, St Petersburg, FL USA
[13] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA 94143 USA
[14] Duke Univ, Med Ctr, Dept Pediat, Div Pediat Infect Dis, Durham, NC 27710 USA
[15] Hippokrateion Hosp, Pediat Intens Care Unit, Thessaloniki, Greece