Abstract

Background Necrotizing enterocolitis (NEC) is one of the most severe gastrointestinal emergencies in preterm infants (PIs), and gut dysbiosis plays an important role in its pathogenesis. This study aimed to investigate the relationship between gut microbiota establishment patterns and the risk of NEC in PIs, analyze risk factors influencing microbiota establishment, and provide scientific evidence for the early prevention of NEC. Methods In this retrospective cohort study, data of 174 PIs admitted between January 2023 and December 2024 were analyzed, including 58 cases in the NEC group and 116 cases in the control group (CG). 16S rRNA high-throughput sequencing was used to analyze the gut microbiota composition at 3, 7, 14, and 21 days after birth. The Shannon index and Simpson index were calculated to assess microbiota diversity. The relative abundance of major genera including Bifidobacterium, Lactobacillus, and Enterobacteriaceae, was analyzed. Clinical data including gestational age, birth weight, feeding method, and antibiotic use were collected. Logistic regression analysis was used to identify the risk factors for NEC. Results The NEC group showed significantly lower gestational age and birth weight than the CG (P<0.05). At 14 days after birth, the NEC group exhibited significantly lower Shannon index and Simpson index than the CG (P<0.05). The relative abundances of Bifidobacterium and Lactobacillus were significantly reduced, while those of Enterobacteriaceae and Klebsiella were significantly increased (P<0.05). Multivariate logistic regression analysis revealed that birth weight, feeding intolerance, duration of antibiotic use, broad-spectrum antibiotic use, and Shannon index were independent risk factors for the occurrence of NEC (P<0.05). Conclusions Reduced gut microbiota diversity, decreased beneficial bacteria, and increased pathogenic bacteria in PIs are closely associated with the occurrence of NEC.