Nutritional strategies and gut microbiota composition as risk factors for necrotizing enterocolitis in very-preterm infants

Abstract

Background: The pathophysiology of necrotizing enterocolitis (NEC) remains poorly understood.Objective: We assessed the relation between feeding strategies, intestinal microbiota composition, and the development of NEC.Design: We performed a prospective nationwide population-based study, EPIPAGE 2 (Etude Epidémiologique sur les Petits Ages Gestationnels), including preterm infants born at <32 wk of gestation in France in 2011. From individual characteristics observed during the first week of life, we calculated a propensity score for the risk of NEC (Bell's stage 2 or 3) after day 7 of life. We analyzed the relation between neonatal intensive care unit (NICU) strategies concerning the rate of progression of enteral feeding, the direct-breastfeeding policy, and the onset of NEC using general linear mixed models to account for clustering by the NICU. An ancillary propensity-matched case-control study, EPIFLORE (Etude Epidémiologique de la flore), in 20 of the 64 NICUs, analyzed the intestinal microbiota by culture and 16S ribosomal RNA gene sequencing.Results: Among the 3161 enrolled preterm infants, 106 (3.4%; 95% CI: 2.8%, 4.0%) developed NEC. Individual characteristics were significantly associated with NEC. Slower and intermediate rates of progression of enteral feeding strategies were associated with a higher risk of NEC, with an adjusted OR of 2.3 (95% CI: 1.2, 4.5; P = 0.01) and 2.0 (95% CI: 1.1, 3.5; P = 0.02), respectively. Less favorable and intermediate direct-breastfeeding policies were associated with higher NEC risk as well, with an adjusted OR of 2.5 (95% CI: 1.1, 5.8; P = 0.03) and 2.3 (95% CI: 1.1, 4.8; P = 0.02), respectively. Microbiota analysis performed in 16 cases and 78 controls showed an association between Clostridium neonatale and Staphylococcus aureus with NEC (P = 0.001 and P = 0.002).Conclusions: A slow rate of progression of enteral feeding and a less favorable direct-breastfeeding policy are associated with an increased risk of developing NEC. For a given level of risk assessed by propensity score, colonization by C. neonatale and/or S. aureus is significantly associated with NEC. This trial (EPIFLORE study) was registered at clinicaltrials.gov as NCT01127698.

Keywords: breastfeeding; clostridia; necrotizing enterocolitis; preterm infant; speed of increasing enteral nutrition.

FIGURE 1

Flowchart of infants enrolled in the study. NEC, necrotizing enterocolitis; NICU, neonatal intensive care unit.

FIGURE 2

Nutritional NICU profiles concerning the rate of progression of enteral feeding policy (A). Each NICU was classified as slower, intermediate, or faster according to the difference between the observed and the expected rate of infants receiving a low enteral volume at day 7. The volume of enteral feeding at day 3 and day 7 and the age at onset of enteral feeding and at the end of parenteral feeding were compared between NICU profiles according to gestational age. Nutritional NICU profiles concerning direct-breastfeeding policy (B). Each NICU was classified as less favorable, intermediate, or more favorable to direct-breastfeeding according to the difference between the observed and the expected rate of partially direct-breastfed infants at day 28. The rate of infants in contact with the mother's breast during the first week and the rate of breastfed infants at day 28 (partial direct-breastfeeding) and at discharge (total direct-breastfeeding) were compared between NICU profiles according to gestational age. ¹P assessed by ANOVA for comparison among infants of 24–26 wk of gestation. ²P assessed by ANOVA for comparison among infants of 27–29 wk of gestation. ³P assessed by ANOVA for comparison among infants of 30–31 wk of gestation. ⁴P assessed by chi-square test for comparison among infants of 24–26 wk of gestation. ⁵P assessed by chi-square test for comparison among infants of 27–29 wk of gestation. ⁶P assessed by chi-square test for comparison among infants of 30–31 wk of gestation. NICU, neonatal intensive care units.

FIGURE 3

Gut microbiota associated with NEC by culture-based analyses in preterm infants enrolled in the ancillary propensity score–matched case-control study. (A) At the genus level, Clostridium is more often observed in NEC cases than in controls (P < 0.001 by chi-square test). (B) At the species level, C. neonatale is more often observed in cases than in controls (P < 0.01 by Fisher's exact test). C., Clostridium; Cl.7, other Clostridium species; NEC, necrotizing enterocolitis; NICU, neonatal intensive care unit.