Background. Feeding intolerance (FI) is a common complication that may cause great harm to preterm infants. The mechanism of FI remains unclear, but probiotics may help prevent and alleviate its symptoms. We hypothesized that the alteration in gut microbiota may be associated with the development of FI. Our study aimed to investigate the association between gut microbiota and FI in preterm infants.

Methods. Ninety-seven preterm infants were divided into the FI group (N=42) and the feeding tolerance (FT) group (N=55) depending on whether the infants were diagnosed with FI. The fecal samples of each infant were collected on the 7th day after birth. Fecal microbiota was analyzed by 16S rRNA sequencing. Plasma motilin were detected on day-1, 7, 14, and 21.

Results. The microbial diversity of the FI group was significantly lower than that of the FT group. The abundance levels of phylum Proteobacteria, class Gammaproteobacteria, genera such as Escherichia/Shigella were higher in the FI group than in the FT group. The abundance levels of phylum Firmicutes, class Negativicutes, and genus Veillonella were higher in the FT group than in the FI group. The motilin levels on days 7 and 14 were negatively correlated with the FI-enriched genera Planomicrobium and Vibrio, respectively. Our study also found gut microbiota was correlated with FI clinical characteristics, including gestational age, birth weight, age of FI diagnosis, age of FI disappearance, and FI duration.

Conclusions. Altered gut microbiota is associated with FI in preterm infants. FI cases typically have lower microbial diversity, a decreased abundance of beneficial bacteria, and an increased abundance of pathogenic bacteria. Gut microbiota is correlated with the clinical characteristics of FI. The decrease in motilin secretion caused by some bacteria may lead to the occurrence of FI.

Keywords: 16S rRNA gene, feeding intolerance, gut microbiota, motilin, preterm infant