[1] Stanford Univ, Dept Pediat, Div Pediat Infect Dis, Stanford, CA 94305 USA
[2] Washington Univ, Dept Pediat, Div Infect Dis, St Louis, MO 63130 USA
[3] Univ Washington, Dept Pediat, Div Pediat Infect Dis, Seattle, WA 98195 USA
[4] Univ Utah, Dept Pediat, Div Pediat Infect Dis, Salt Lake City, UT USA
[5] Childrens Hosp Philadelphia, Div Pediat Infect Dis, Philadelphia, PA 19104 USA