In the current study, researchers examined the relationships between microbial exposure and the composition of the fecal microbiome and atopic outcomes in the cohort of infants born and raised during the social exclusion caused by the coronavirus illness 2019 (COVID-19) (CORAL). The majority of newborns in this cohort were males (55%), Caucasian (96%), and vaginally delivered (65%).

The group sequenced 16S ribosomal RNA (rRNA) from samples of newborn feces. They discovered a significant correlation between age and microbiota composition and the manner of birth. 33% of the bacterial families that were found had an age component.

At the order level, Bacteroidales, Erysipelotrichales, Coriobacteriales, Verrucomicrobiales, and Clostridiales rose from six months to one year, while Veillonellales, Enterobacteriales, Lactobacillales, and Bifidobacteriales dropped.

A higher relative abundance was linked to either intrapartum antibiotic exposure or cesarean section (CS) birthThe effects of CS delivery, intrapartum antibiotics, and medical interventions were higher at six months, while the impact of environmental factors and exposure to human contacts increased at one year. In addition, the intake frequency of beans, grains, sesame seeds, and vegetable oil was significantly associated with microbiota composition at six months.

Additionally, walnuts, soy, cow’s milk, and pecan ingestion significantly contributed at 12 months. The effect of beans, nuts, and oil was similar to that of vaginal delivery and breastfeeding, with higher relative abundances of Bifidobacterium, Collinsella, Bacteroides, and Lactobacillus at either time point. However, consuming cow’s milk formula had the reverse effect at 12 months, with the microbiota composition shifting away from the Bacteroides/Bifidobacterium-dominated one.

The impact of human exposure-linked factors increased by one year, shifting the infant-type microbial composition to a more mature one with higher abundances of Lachnospiraceae and Ruminococcaceae.

The scientists next looked at how much the microbiome mediated the effects of epidemiologic factors as environmental factors (such as diet, nursing, etc.) have been identified as epidemiologic factors impacting food allergen sensitivity and atopic dermatitis.

In order to compare how exposure affected disease outcomes, they used logistic regression models. Atopic dermatitis at 12 months was significantly predicted by the gut microbiota composition at both time periods. Smoking and daycare attendance were positively correlated with atopic dermatitis. It exhibited a bad correlation with living in rural areas and using antibiotics between six and twelve months of age.

Antibiotics and childcare had impacts that were mediated by the microbiome, whereas smoking mostly had direct consequences. The consumption of fish, pistachios, starchy vegetables, and other foods by infants was also positively correlated with atopic dermatitis.