[1] Childrens Hosp, Dept Pathol, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Childrens Hosp, Combined Program Pediat Gastroenterol, Boston, MA 02115 USA
[4] Harvard Univ, Sch Med, Dept Pediat, Boston, MA 02115 USA
[5] Brigham & Womens Hosp, Div Gastroenterol, Boston, MA 02115 USA
[6] Harvard Univ, Sch Med, Dept Med, Boston, MA 02115 USA
[7] Univ Colorado, Hlth Sci Ctr, Dept Microbiol, Denver, CO 80262 USA
[8] Harvard Digest Dis Ctr, Boston, MA 02115 USA