Does Intestinal Microbiota Affect Weight Gain in Preterm Neonates?

Presenter: G. Solís (e-mail: [e-mail])

Introduction: The early neonatal period represents the most important moment for the microbiota-induced maturation of the host, being a key determinant factor for later health. The neonatal gut colonization, which begins with facultative anaerobes and continues with anaerobic genera, is affected by several factors. Different studies have demonstrated the involvement of the gut microbiota on weight-gain and obesity. More recently, different animal studies have suggested a relationship between the microbiota and childhood undernutrition and growth. Thus, the modulation of the gut microbiota could be a potential therapeutic target for promoting growth and preventing growth impairment. However, little is known about the potential relationship among microbiota establishment, growth and development in preterm infants. The aim of the present study was to evaluate such potential relationship between early microbiota development in the preterm infant and weight gain.

Materials and Methods: Sixty-three preterm infants (gestational ages ranging from 28 to 33 weeks) were recruited at the Neonatology Units of Cabueñes Hospital and the University Central Hospital (HUCA) of Asturias (northern Spain). Fecal samples were collected at 2, 10 and 30 days of age and weights were determined monthly up to 3 months of age. Quantification of the different bacterial populations assessed (Bifidobacteriaceae, Streptococcaceae, Staphylococcaceae, Enterococcaceae, Bacteriodaceae, Enterobacteriaceae, Lactobacillaceae, Weissella and total bacteria) was performed by quantitative PCR and the concentration of the main short chain fatty acids (SCFA) in feces was achieved by gas chromatography. The data obtained were submitted to multiple mixed linear models analyses to investigate the relationship between microbial levels (and fecal SCFA) and weight-gain adjusted by possible confounders. Besides, backward stepwise based on the Akaike Information Criterion (AIC) were included to determine whether the observed associations were included in predictive models. A forest plot was used to show the effect sizes in both the so-labeled univariate and the multivariate models (always adjusting by infant and gestational ages).

Results: The generalized mixed linear effects model showed a large effect of infant age and gestational age. Therefore, to further assess the associations the model was adjusted for these two variables and analyzed by multivariate regression models to determine the effects of the microbiota-related variables used. The results obtained indicate an influence of the intestinal microbiota in weight-gain in preterm infants as shown in the forest plot represented in Fig. 1. To evaluate the ability of the early microbiota-related variables for predicting weight-gain in preterm infants, the association of the microbiota parameters at 2 and 10 days of age with the weight gained at 30 days of age was studied. After adjusting for gestation age, the levels of Enterobacteriaceae at 2 and 10 days of age, Streptococcaceae and total bacteria levels at 2 days and those of Bacteroides at 10 days of age were found to have a significant effect upon weight gain.

Conclusion: Our results suggest an effect of the gut microbiota in weight-gain of preterm infants at the early ages of life. These observations point out at the microbiota as a potential target for favoring growth and maturation in preterm infants, which may have further consequences in reducing disease risk.

Keywords: microbiota, preterm newborn, growth