Clinical characteristics of infants in this study.

Matched samples are indicated by the letters in the label; for example, samples 11A, 11B, and 11C were derived from the same patient. Unknown data is indicated by the abbreviation UNK; NA, not applicable; DOL, day of life.Abbreviations for tissue types: J, jejunum; I, ileum; C, cecum; RC, right colon; TC, transverse colon; LC, left colon.Abbreviations for mode of delivery are CS, Cesarean section; V, vaginal delivery.Feeding refers to enteral nutrition received in the week prior to sample collection, and the abbreviations for feeding are: BM, breast milk; FF, formula feed; C, combination breast and formula; NPO, no feeds.Perinatal antibiotics refers to the initial course of antibiotics consecutively administered to the baby after delivery. Abbreviations for antibiotics: A, ampicillin; G, gentamycin; V, vancomycin, Cl, clindamycin; Cf, cefotaxime.Preoperative antibiotic days refer to the number of consecutive days on which antibiotics were administered immediately preceding sample collection. This excludes antibiotics administered at time of surgery.Clinical characteristics of infants in this study.