Preterm infants are usually at a higher risk of necrotizing enterocolitis (NEC), which has been linked to an altered gut microbiota composition and metabolome. For instance, an overgrowth of pathobionts including Enterobacter, Escherichia and Klebsiella spp. has been associated with NEC, nosocomial infections and late-onset sepsis.
New findings led by Dr. Lindsay Hall from Quadram Institute Bioscience in Norwich (United Kingdom) reveal that supplementation with Bifidobacterium bifidum and Lactobacillus acidophilus can shift the preterm gut microbiota towards that of a healthy full-term breastfed infant.
In an attempt to explore whether members of the early-life gut microbiota can aid in shaping the preterm infant’s gut microbiota, the authors compared fecal samples collected at four time points from two matched cohorts of preterm infants from different neonatal intensive care units. The first cohort (n= 101) received oral supplementation of a probiotic containing B. bifidum and L. acidophilus with the first enteral feed, while the second cohort (control group; n = 133) did not.
An analysis of gut microbiota composition using 16S ribosomal ribonucleic acid gene profiling showed that the fecal microbiota of preterm infants supplemented with the probiotic had a predominance of Bifidobacterium and a lower abundance of pathobionts. Preterm infants with low birth weight (less than 1,000g) showed the lowest abundance of Bifidobacterium. Levels were subsequently enhanced after supplementation, providing a potential strategy for consideration for that vulnerable group of infants.
At metabolomic level, the preterm infants who received the probiotic showed higher fecal acetate and lactate levels and a lower fecal pH. In addition, fecal acetate positively correlated with relative abundance of Bifidobacterium, which the authors attributed to the supplemented Bifidobacterium strain’s capacity to metabolize human milk oligosaccharides into acetate, coupled with acetate and lactate generated as major products of said gut commensal.
Whole-genome sequencing revealed that supplemented strains were capable of metabolizing breast milk and human milk oligosaccharides, while also persisting within the preterm gut microbiota after supplementation.
Parallel studies also allowed the authors to define factors that may impact supplemented strains and their persistence within the preterm gut microbiota. Major drivers of gut microbiota diversity included diet and antibiotic prescription. In contrast, delivery method did not affect Bifidobacterium abundance.
The new study shows that supplementing preterm infants with probiotic strains of Bifidobacterium and Lactobacillus alter gut microbiota and gut metabolites composition toward a state that resembles the gut microbiota of full-term infants. Those findings support the acknowledged role of probiotic supplementation in reducing the risk of NEC in preterm neonates compiled in some clinical guidelines, although not all the probiotics preparations tested have been shown to be effective.
Alcon-Giner C, Dalby MJ, Caim S, et al. Microbiota supplementation with Bifidobacterium and Lactobacillus modifies the preterm infant gut microbiota and metabolome: an observational study. Cell Rep Med. 2020; 1:100077. doi: 10.1016/j.xcrm.2020.100077.