Microbial transmission from mother to child: improving infant intestinal microbiota development by identifying the obstacles.

Industrialisation has introduced several lifestyle changes and medical advancements but their impact on intestinal microbiota acquisition is often overlooked. Even though these consequential changes in the microbiota could contribute to the disease burden that accompanies industrialisation, such as obesity and atopic disease. A healthy intestinal microbiota is acquired early in life but its exact origin is not fully elucidated. The maternal microbiota is a likely source because the infant and mother intestinal microbiota share identical strains. Successfully transmitting microbes from mother to child requires microbes in the maternal donor, contact between the maternal source and the infant, and an acquiring infant recipient. Transmission can be altered by changes to any of those three transmission determinants: (1) maternal microbiota sources are shaped by the mother's genotype, diet, health status and perturbing antimicrobial exposure; (2) maternal contact is reduced through C-section and formula feeding and (3) engraftment in the infant recipient is determined by host habitat filtering, the established microbes and antibiotic disruptions. This review gives an overview of the possible maternal transmission routes, the disruptions thereof, and the missing links that should be addressed in future research to investigate the maternal transmissions that are crucial for obtaining a healthy infant microbiota.

Effect of antibiotics in the first week of life on faecal microbiota development.

BACKGROUND: Infants are frequently exposed to antibiotics (AB) in the first week of life for suspected bacterial infections. Little is known about the effect of AB on the developing intestinal microbiota. Therefore, we studied intestinal microbiota development with and without AB exposure in the first week of life in term born infants. METHODS: We analysed the faecal microbiota from birth until 2.5 years of age by 16S rRNA gene amplicon sequencing in a cohort with 56 term born infants, exposed to AB in the first week of life (AB+) (AB for 2-3 days (AB2, n=20), AB for 7 days (AB7, n=36)), compared with 126 healthy controls (AB-). The effects of AB and duration were examined in relation to delivery and feeding mode. RESULTS: AB+ was associated with significantly increased relative abundance of Enterobacteriaceae at 3 weeks and 1 year and a decrease of Bifidobacteriaceae, from 1 week until 3 months of age only in vaginally delivered, but not in C-section born infants. Similar deviations were noted in AB7, but not in AB2. After AB, breastfed infants had lower relative abundance of potentially pathogenic Enterobacteriaceae compared with formula fed infants and recovered 2 weeks faster towards controls. CONCLUSIONS: AB exposure in the first week of life alters faecal microbiota development with deviations in the relative abundance of individual taxa until 1 year of age. These alterations can have long-term health consequences, which emphasises the need for future studies aiming at restoring intestinal microbiota after AB administration.

Early life antibiotics and childhood gastrointestinal disorders: a systematic review.

Background: In adults, there is increasing evidence for an association between antibiotic use and gastrointestinal (GI) disorders but in children, the evidence is scarce. Objective: Assess the association between exposure to antibiotics in the first 2 years of life in term born children and the presence of chronic GI disorders later in childhood. Design: For this systematic review the MEDLINE, Embase, WHO trial register and Web of Science were systematically searched from inception to 8 June 2020. Title and abstract screening (n=12 219), full-text screening (n=132) as well as the quality assessment with the Newcastle-Ottawa Scale were independently performed by two researchers. Main outcome measures: The association between antibiotics and inflammatory bowel disease (IBD) (n=6), eosinophilic oesophagitis (EoE) (n=5), coeliac disease (CeD) (n=6), infantile colics (n=3), functional constipation (n=2), recurrent abdominal pain, regurgitation, functional diarrhoea and infant dyschezia were examined. Results: Twenty-two studies were included, 11 cohort and 11 case-control studies. A best evidence synthesis showed strong evidence for an association between antibiotic exposure in the first 2 years of life and the presence of IBD, and CeD during childhood. Moderate evidence was found for an association with EoE and no association with functional constipation in the first year of life. There was insufficient evidence for the other studied disorders. Conclusions: The use of antibiotics in early life may increase the risk of GI disorders later in life. Further studies are necessary to unravel the underlying mechanisms and determine potential preventive measures. Meanwhile judicious use of antibiotics in early childhood is highly warranted. PROSPERO registration number: PROSPERO CRD42019132631.