Patient Characteristics: HAEC.

aSample ID and site identification: 01—Cedars-Sinai Medical Center, Los Angeles, California; 02- Karolinska Institute, Stockholm, Sweden; 03—Children’s Hospital Los Angeles, Los Angeles, California; 04—Children’s Hospital of Oakland, Oakland, California. # This subject was excluded from analysis because he had active HAEC at the time of stool collection. bLocation of TZ: location of transition zone from normal to aganglionic bowel. RS = rectosigmoid colon; Il = ileum. cDiet: Diet in the first year of life dUnk = unknown eAbx: Antibiotics received within the 2 months prior to stool collection for this analysis. * = Metronidazole; ** = Penicillin prophylaxis daily for sickle cell disease. fProbiotics: LB = lactobacillus sp. and bifidobacterium sp. combined; Lr = Lactobacillus reuteri; LG = Lactobacillus GG. g30-day compl: Complications occurring within 30 days of the pull-through operation. IH = internal hernia requiring surgical intervention requiring intestinal resection and ileostomy creation. HAEC = Hirschsprung-associated enterocolitis. AS = anastomotic stricture requiring dilatation. hChr. Anomalies: Chromosomal or known genetic mutations. Ts 21 = Trisomy 21; SC = Sickle cell disease. Patient Characteristics: HAEC.