The gut microbiota is essential for health throughout life, and a recent study published in Cell Host & Microbe investigated the father's role in intestinal seeding in infants and the impact of induced seeding via maternal fecal microbiota transplant (FMT).
Study: Seeding of paternally derived and induced gut microbiota complements maternal-fetal transmission. Image credit: Natalia Deriabina/Shutterstock.com
The impact of caesarean section on a child's health
The fetal gut is sterile and seeding begins after birth. Microbial transmission between mother and child occurs during and after labor and accounts for approximately 50% of the microbial taxa in the infant's gut by 1 year of age. This process can be interrupted by cesarean section, as vaginal delivery also promotes microbial colonization of the infant's gut.
Mothers who undergo Caesarean section are often given antibiotics to reduce the risk of postoperative infection, and antibiotic treatment may alter the composition of the maternal microbiota, reducing the amount of maternal bacteria available to colonize the infant's gut.
Caesarean section currently accounts for over 25% of births worldwide. Breastfeeding, skin-to-skin contact, and antibiotic stewardship can be utilized to reduce the impact of cesarean section on infant gut colonization.
Currently, researchers estimate that approximately half of the strains found in the fetal microbiome are not maternally transmitted. Thus, in addition to the maternal influence on the development of the infant's gut microbiome, individuals in close proximity to the infant may also be a source of health-related microorganisms. However, which species are transmitted from these individuals and their functional role in the infant's gut microbiome remain poorly understood.
What did the study find?
The aim of this study was to investigate the shared gut microbiota between parents and infants and changes in its composition during the first year of life in infants born vaginally and by cesarean section.
The researchers analyzed two metagenomic data sets from 81 infants and 433 samples. A total of 285 and 113 samples were obtained from 53 vaginal deliveries and 21 cesarean sections, respectively. Thirty-five samples from seven infants born by cesarean section in the Finnish SECFLOR study who subsequently underwent maternal FMT were also included in the analysis.
Changes in the gut microbiota of infants
Although initially very different from the adult gut, the infant gut became more similar to that of its parents over time. Infant age and intrapartum antibiotic prophylaxis (IAP) were the strongest predictors of differences in gut microbiota composition compared with mode of delivery.
Infants received a significant amount of microbial inoculum from their mothers by 3 weeks of age, with inoculum rates declining from 61% to 30% at 3 weeks and 12 months, respectively. For fathers, microbial sharing declined to 25% by 3 weeks, but then remained at 20-22% until 12 months. Thus, maternal and paternal contributions were very similar regardless of mode of delivery.
Each parent contributes a different proportion of microbiota diversity to their infant.”
Mothers appear to be vectors of Bacteroides spp., and five of the six species more commonly shared with mothers were relatively more prevalent in infants born vaginally compared with infants born by cesarean section.
FMT and infant gut microbiota richness
Infants who underwent FMT had significantly more gut microbiota than both infants born by cesarean section who did not receive FMT and infants born by vaginal delivery.
Receiving FMT from the mother increases the rate of gut bacterial overgrowth in infants, and although maternal FMT also increases the sharing of bacterial strains with the mother, FMT may introduce bacterial species not normally found in infants.
Babies born by cesarean section showed differences in the relative abundance of 16 species, eight of which were restored by FMT to levels similar to those in vaginally delivered babies, while the remaining species reached higher levels in the FMT group than in vaginally delivered babies.
FMT produced observable and stable seedlings throughout the study period, however, FMT-derived seeds exhibited reduced growth rates over time compared to seeds obtained by natural seeding.
Strict anaerobes and some fiber-degrading species have poor survival rates when introduced by FMT. In contrast, because infants often drink breast milk during the first months of life, the ability to degrade human milk oligosaccharides (HMOs) appears to be advantageous for their growth.
Further studies are needed to compare the outcomes of induced and natural seeding, which will shape future FMT prescriptions and administration.
FMT and pathogen colonization
FMT reduced the likelihood of intestinal pathogen colonization to a similar level to that of vaginally delivered infants not exposed to IAP. Colonization with this type of microorganism was higher in cesarean section infants and similar to that of vaginally delivered infants exposed to IAP.
IAP and the infant gut microbiota
IAP affects the composition of the gut microbiota in both mothers and infants, increasing pathogen colonization.
Taxa such as Clostridium perfringens, Enterococcus fecalis, two Klebsiella species, and Staphylococcus aureus were more common in infants than in adults, although Staphylococcus aureus was more common in infants born by cesarean section than in those born vaginally. In infants born vaginally, E. fecalis and K. pneumoniae were more common if their mothers had undergone IAP.
Conclusion
Regardless of the mode of delivery, fathers make a stable contribution to the gut microbiome throughout the first year of life, and their contribution increases, eventually becoming equal to that of the mother at that point. The contribution of family members to the development of the infant's microbiome is an important area worthy of further study.
Findings have also shown that antibiotics administered after birth have a negative effect on bacterial growth rate and microbiota maturation.Furthermore, FMT is a promising approach to induce seeding when the natural process is interrupted for various reasons.
Journal References:
Dubois, L., Valles-Colomer, M., Ponsero, A., et al. (2024). Paternal and inducible intestinal microbiota seeding complements maternal-fetal transmission. Cell Host & Microbe. doi:10.1016/j.chom.2024.05.004.
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