The first aim of the study was to correlate the occurrence of a blood stream infection (BSI) during the early phase of necrotizing enterocolitis (NEC) with intestinal fatty acid-binding protein (I-FABP) levels, as a marker for loss of gut wall integrity owing to mucosal damage, and Interleukin (IL)-8 levels, as a biomarker for the pro-inflammatory cascade in NEC. The second aim of the study was to investigate the relation between the occurrence of a BSI and disease outcome. Here, CXCL8 is linked to infection.