Gut colonization by aerobic microorganisms is associated with route and type of nutrition in premature neonates

We hypothesized that the beneficial effects of early enteral compared with parenteral feeding are related to the increased variety of aerobic microorganisms that colonize the gut. Our aim was to describe the relationship, first, between the type of feeding and mucosal colonization and, second, between the type of feeding and the development of late-onset sepsis (LOS) and necrotizing enterocolitis (NEC) in preterm neonates. In total, 159 neonates aged 72 hours or less with risk factors for early-onset sepsis were recruited to a prospective 2-center study. Rectal swabs were collected on admission and twice per week thereafter. The feeding regimen was recorded for the first 7 days and categorized into total parenteral nutrition (TPN) and 2 regimens of enteral nutrition, that is, breast milk containing regimen (BMCR), for which breast milk constituted at least 11% of the enteral diet, or formula. Herein, 70 neonates received formula, 48 received BMCR, and 41 received TPN; 69 cases of LOS and 15 cases of NEC were observed in 50 neonates. A multiple logistic regression analysis indicated that formula and BMCR were associated with 4- to 5-fold increases in colonization by Gram-negative bacteria (odds ratio [OR], 4.52; 1.87-10.95, and OR, 4.95; 1.90-12.87, respectively) and 5 to 9 times higher odds of colonization by Gram-positive microorganisms (OR, 5.75; 1.89-16.72, and OR, 8.61; 2.52-29.36, respectively) compared with TPN. The only difference between BMCR and the other feeding groups was the higher colonization with Staphylococcus haemolyticus in the latter (formula-OR, 6.24; 1.73-22.50; TPN-OR, 2.75; 1.08-6.97). Compared with BMCR, TPN was associated with an increased odds of LOS (OR, 3.04; 1.02-9.07) and an increased odds of death (19.75; 3.64-107.12) compared with formula. Although early enteral feeding is associated with a higher odds of colonization with opportunistic microorganisms, it should be preferred over TPN whenever feasible, due to the favorable effect on the prevention of LOS.