Quantitative insights into effects of intrapartum antibiotics and birth mode on infant gut microbiota in relation to well-being during the first year of life

Early-life gut microbiota associates with allergic rhinitis during 13-year follow-up in a Finnish probiotic intervention cohort

Perinatal and early-life factors reported to affect risk of allergic diseases may be mediated by changes in the gut microbiota. Here, we explored the associations between the infant gut microbiota and allergic morbidity in childhood until 13 years of age in a subgroup of the FLORA probiotic intervention cohort. A mixture of four probiotic strains with galacto-oligosaccharides was administrated to the mothers from the 36th week of the pregnancy and later to their infants until 6 months of age. The infants were monitored for the manifestations of atopic eczema, food allergy, allergic rhinitis, and asthma by a pediatrician at 2 and 5 years of age; the allergic status was subsequently verified by a questionnaire at 10 and 13 years of age. The fecal microbiota at 3 months was profiled by 16S rRNA amplicon sequencing targeting the V3-V4 region, with and without adjusting for potentially important early-life factors. Overall, the positive diagnosis for allergic rhinitis between 2 and 13 years was associated with microbiota composition both in non-adjusted and adjusted models. This association was more pronounced in children born to one parent with confirmed atopic diseases compared to those who had two atopic parents and was characterized by a lower relative abundance of Bifidobacterium and Escherichia/Shigella spp. and a higher proportion of Bacteroides. While the probiotic and galacto-oligosaccharides intervention in the entire cohort was previously shown to reduce the prevalence of eczema to a certain extent, no associations were found between the 3-month gut microbiota and childhood eczema in the studied sub-cohort.IMPORTANCEAllergic diseases have increased in prevalence during the past decades globally. Although probiotics have been considered a promising strategy for preventing certain allergy related symptoms, studies connecting the infant gut microbiota and later life allergic morbidity in various populations remain limited. The present study supports an association between the infant microbiota and allergic morbidity after first years of life, which has been rarely examined.CLINICAL TRIALSRegistered at ClinicalTrials.gov (NCT00298337).

Bowel function in a prospective cohort of 1052 healthy term infants up to 4 months of age

The purpose of this study is to describe the defecation pattern of healthy infants up to 17 weeks of age. We included 1052 healthy term infants from the prospective HELMi cohort (NCT03996304). Parents filled in recurring online questionnaires on feeding, gastrointestinal function, and crying weekly for the first 17 weeks of life. Defecation frequency was highest at the age of 3 weeks (a median of 4 times/day, interquartile range (IQR) 2.9-5). At each time point, the median defecation frequency of breastfed infants was higher than that of infants receiving formula (e.g., at week 17 a median of 2 times/day, IQR 0.9-3.6, and a median of 1.1, IQR 0.6-1.4, respectively). The dominant color of the stool was most often yellow or light brown. Nearly black stools were reported in the first week of life in 3.4%. Nearly half (47.4%) of the infants had green stool color dominating for at least 1 week, with comparable frequency among breastfed (47.7%) and formula-fed (45.2%) infants. Green stools were associated with a higher defecation frequency (linear mixed-effect model p < 0.0001). Occasional blood in stool was reported in 9.3% and recurrent blood in 5.2% of the infants with no difference in stool consistency. Hard stools were rare (≤ 1%).     Conclusion: This study enlightens the spectrum of defecation patterns in healthy term infants during the first 17 weeks of life. A better understanding of bowel function helps healthcare professionals distinguish normal from abnormal when addressing defecation, the color of stools, and the type of feeding. What is Known: • Breastfed infants have more frequent and more yellow-colored stools than formula-fed infants. • Stools with green color are often suggested by the parents or even by medical professionals to indicate disease or discomfort in early life. What is New: • Nearly half of the healthy term infants had green stool dominating for at least one week during the first 17 weeks and occasional blood was reported in almost 10% of the infants during this period. • Data on normal variation in bowel function and stool may serve primary health care professionals when educating the families and caretakers of infants.

Early-life exposures and the microbiome: implications for IBD prevention

The early-life period is one of microbiome establishment and immune maturation. Early-life exposures are increasingly being recognised to play an important role in IBD risk. The composition of functions of the gut microbiome in the prenatal, perinatal, and postnatal period may be crucial towards development of health or disease, including IBD, later in life. We herein present a comprehensive summary of the interplay between early-life factors and microbiome perturbations, and their association with risk of IBD. In addition, we provide an overview of host and external factors in early life that are known to impact gut microbiome maturation and exposures implicated in IBD risk. Considering the emerging concept of IBD prevention, we propose strategies to minimise maternal and offspring exposure to potentially harmful variables and recommend protective measures during pregnancy and the postpartum period. This holistic view of early-life factors and microbiome signatures among mothers and their offspring will help frame our current understanding of their importance towards IBD pathogenesis and frame the roadmap for preventive strategies.

The infant gut microbiota as the cornerstone for future gastrointestinal health

The early postnatal period represents a critical window of time for the establishment and maturation of the human gut microbiota. The gut microbiota undergoes dramatic developmental changes during the first year of life, being influenced by a variety of external factors, with diet being a major player. Indeed, the introduction of complementary feeding provides novel nutritive substrates and triggers a shift from milk-adapted gut microbiota toward an adult-like bacterial composition, which is characterized by an enhancement in diversity and proportions of fiber-degrading bacterial genera like Ruminococcus, Prevotella, Eubacterium, and Bacteroides genera. Inadequate gut microbiota development in early life is frequently associated with concomitant and future adverse health conditions. Thus, understanding the processes that govern initial colonization and establishment of microbes in the gastrointestinal tract is of great importance. This review summarizes the actual understanding of the assembly and development of the microbial community associated with the infant gut, emphasizing the importance of mother-to-infant vertical transmission events as a fundamental arrival route for the first colonizers.

Effects of maternal type 1 diabetes and confounding factors on neonatal microbiomes

AIMS/HYPOTHESIS

Body niche-specific microbiota in maternal-neonatal dyads from gravidae with type 1 diabetes have not been quantitatively and functionally examined. Similarly, the impact of pregnancy-specific factors, such as the presence of comorbidities known to occur more frequently among gravidae with type 1 diabetes, including Caesarean delivery, as well as antibiotic prophylaxis, level of glycaemic control during each trimester of pregnancy and insulin administration, has not been adequately considered. The aims of this study were to characterise the maternal and neonatal microbiomes, assess aspects of microbiota transfer from the maternal microbiomes to the neonatal microbiome and explore the impact of type 1 diabetes and confounding factors on the microbiomes.

METHODS

In this observational case-control study, we characterised microbiome community composition and function using 16S rRNA amplicon sequencing in a total of 514 vaginal, rectal and ear-skin swabs and stool samples derived from 92 maternal-neonatal dyads (including 50 gravidae with type 1 diabetes) and in-depth clinical metadata from throughout pregnancy and delivery.

RESULTS

Type 1 diabetes-specific microbiota were identified among gravidae with type 1 diabetes and their neonates. Neonatal microbiome profiles of ear-skin swabs and stool samples were established, indicating the taxa more prevalent among neonates born to mothers with type 1 diabetes compared with neonates born to control mothers. Without taking into account the type 1 diabetes status of mothers, both delivery mode and intrapartum antibiotic prophylaxis were found to have an influence on neonatal microbiota composition (both p=0.001). In the logistic regression analysis involving all confounding variables, neonatal ear-skin microbiome variation was explained by maternal type 1 diabetes status (p=0.020) and small for gestational age birthweight (p=0.050). Moreover, in women with type 1 diabetes, a relationship was found between HbA1c levels >55 mmol/mol (>7.2%) measured in the first trimester of pregnancy and neonatal ear-skin microbiota composition (p=0.008). In the PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) assessment, pathways concerning carbohydrate biosynthesis were predicted as key elements of the microbial functional profiles dysregulated in type 1 diabetes. Additionally, in SourceTracker analysis, we found that, on average, 81.0% of neonatal microbiota was attributed to maternal sources. An increase in the contribution of maternal rectum microbiota and decrease in the contribution of maternal cervix microbiota were found in ear-skin samples of vaginally delivered neonates of mothers with type 1 diabetes compared with neonates born to control mothers (83.2% vs 59.5% and 0.7% vs 5.2%, respectively).

CONCLUSIONS/INTERPRETATION

These findings indicate that, in addition to maternal type 1 diabetes, glycaemic dysregulation before/in the first trimester of pregnancy, mode of delivery and intrapartum antibiotic prophylaxis may contribute to the inoculation and formation of the neonatal microbiomes.

DATA AVAILABILITY

The BioProject (PRJNA961636) and associated SRA metadata are available at http://www.ncbi.nlm.nih.gov/bioproject/961636 . Processed data on probiotic supplementation and the PICRUSt analysis are available in the Mendeley Data Repository ( https://doi.org/10.17632/g68rwnnrfk.1 ).

Machine-learning analysis of cross-study samples according to the gut microbiome in 12 infant cohorts

IMPORTANCE

There are challenges in merging microbiome data from diverse research groups due to the intricate and multifaceted nature of such data. To address this, we utilized a combination of machine-learning (ML) models to analyze 16S sequencing data from a substantial set of gut microbiome samples, sourced from 12 distinct infant cohorts that were gathered prospectively. Our initial focus was on the mode of delivery due to its prior association with changes in infant gut microbiomes. Through ML analysis, we demonstrated the effective merging and comparison of various gut microbiome data sets, facilitating the identification of robust microbiome biomarkers applicable across varied study populations.

Perinatal and Other Risk Factors for Common Infections in Infancy: A Prospective Cohort Study

OBJECTIVE

Limited data from prospective cohort studies in high-income countries are available on the perinatal risk factors for common infections in children. Our hypothesis was that perinatal factors may be risk factors for infectious episodes during the first year of life.

METHODS

In this prospective Health and Early Life Microbiota birth cohort study of full-term infants (n = 1052) born in 2016-2018, the number and duration of infection episodes were collected online at weekly to monthly intervals. In a multivariate regression model, the main exposures were perinatal factors such as mode of delivery and intrapartum antibiotics. Environmental factors were additional exposures. The outcomes were the number and duration of infectious episodes in the first year of life.

RESULTS

The mean number of infection episodes was 4.2 (2.9 SD). The mean duration of infection symptoms was 44 days (40 SD). Upper respiratory infections accounted for 83% of the episodes (3674/4455). Perinatal factors were not associated with the number nor the duration of infection episodes, but cesarean section was associated with an increased occurrence of urinary tract infections in infancy [adjusted odds ratio (aOR): 3.6; 95% confidence interval (CI): 1.13-11.1]. Of the additional exposures male sex (aOR: 1.1; 95% CI: 1.0-1.2) and the presence of siblings (aOR: 1.3; 95% CI: 1.2-1.4) were associated with the number of infection episodes.

CONCLUSIONS

This prospective cohort study showed that perinatal factors, mode of delivery and intrapartum antibiotics were not associated with the risk of common infections in infancy, but cesarean delivery was associated with a risk of urinary tract infections.

Development of the early-life gut microbiome and associations with eczema in a prospective Chinese cohort

IMPORTANCE

Eczema is a major allergic disease in children, which is particularly prevalent in Chinese children during their first year of life. In this study, we showed that alterations in the infant gut microbiota precede the development of eczema in a prospective Chinese cohort. In particular, we discovered enrichments of the genera Clostridium sensu stricto 1 and Finegoldia in the cases at 3 and 1 month of age, respectively, which may represent potential targets for intervention to prevent eczema. Besides, we identified a depletion of Bacteroides from 1 to 6 months of age and an enrichment of Clostridium sensu stricto 1 at 3 months in the eczema cases, patterns also observed in C-section-born infants within the same time frames, providing first evidence to support a role of the gut microbiota in previously reported associations between C-section and increased risk of eczema in infancy.

Sources of gut microbiota variation in a large longitudinal Finnish infant cohort

BACKGROUND

Although the infant gut microbiota has been extensively studied, comprehensive assessment on the microbiota determinants including technical variables has not been performed in large infant cohorts.

METHODS

We studied the effect of 109 variables on the 16S rRNA gene amplicon-based gut microbiota profiles of infants sampled longitudinally from three weeks to two years of life in the Finnish HELMi birth cohort. Spot faecal samples from both parents were included for intra-family analyses, totalling to 7657 samples from 985 families that were evaluated for beta-diversity patterns using permutational multivariate analysis on Bray-Curtis distances, and differential abundance testing and alpha-diversity for variables of interest. We also assessed the effect of different taxonomic levels and distance methods.

FINDINGS

In time point-specific models, the largest share of variation explained, up to 2-6%, were seen in decreasing order for the DNA extraction batch, delivery mode and related perinatal exposures, defecation frequency and parity/siblings. Variables describing the infant gastrointestinal function were continuously important during the first two years, reflecting changes in e.g., feeding habits. The effect of parity/siblings on infant microbiota was modified by birth mode and exposure to intrapartum antibiotics, exemplifying the tight interlinkage of perinatal factors relevant for infant microbiota research. In total, up to 19% of the biological microbiota variation in the infant gut could be explained. Our results highlight the need to interpret variance partitioning results in the context of each cohort's characteristics and microbiota processing.

INTERPRETATION

Our study provides a comprehensive report of key factors associated with infant gut microbiota composition across the two first years of life in a homogenous cohort. The study highlights possible important future research areas and confounding factors to be considered.

FUNDING

This research was supported by Business Finland, Academy of Finland, Foundation for Nutrition Research and the Doctoral Program in Microbiology and Biotechnology, University of Helsinki, Finland.

The Detrimental Effects of Peripartum Antibiotics on Gut Proliferation and Formula Feeding Injury in Neonatal Mice Are Alleviated with Lactobacillus rhamnosus GG

Peripartum antibiotics can negatively impact the developing gut microbiome and are associated with necrotizing enterocolitis (NEC). The mechanisms by which peripartum antibiotics increase the risk of NEC and strategies that can help mitigate this risk remain poorly understood. In this study, we determined mechanisms by which peripartum antibiotics increase neonatal gut injury and evaluated whether probiotics protect against gut injury potentiated by peripartum antibiotics. To accomplish this objective, we administered broad-spectrum antibiotics or sterile water to pregnant C57BL6 mice and induced neonatal gut injury to their pups with formula feeding. We found that pups exposed to antibiotics had reduced villus height, crypt depth, and intestinal olfactomedin 4 and proliferating cell nuclear antigen compared to the controls, indicating that peripartum antibiotics impaired intestinal proliferation. When formula feeding was used to induce NEC-like injury, more severe intestinal injury and apoptosis were observed in the pups exposed to antibiotics compared to the controls. Supplementation with the probiotic Lactobacillus rhamnosus GG (LGG) reduced the severity of formula-induced gut injury potentiated by antibiotics. Increased intestinal proliferating cell nuclear antigen and activation of the Gpr81-Wnt pathway were noted in the pups supplemented with LGG, suggesting partial restoration of intestinal proliferation by probiotics. We conclude that peripartum antibiotics potentiate neonatal gut injury by inhibiting intestinal proliferation. LGG supplementation decreases gut injury by activating the Gpr81-Wnt pathway and restoring intestinal proliferation impaired by peripartum antibiotics. Our results suggest that postnatal probiotics may be effective in mitigating the increased risk of NEC associated with peripartum antibiotic exposure in preterm infants.

Programming Factors of Neonatal Intestinal Dysbiosis as a Cause of Disease

The intestinal microbiota consists of trillions of bacteria, viruses, and fungi that achieve a perfect symbiosis with the host. They perform immunological, metabolic, and endocrine functions in the body. The microbiota is formed intrauterine. Dysbiosis is a microbiome disorder characterized by an imbalance in the composition of the microbiota, as well as changes in their functional and metabolic activities. The causes of dysbiosis include improper nutrition in pregnant women, hormone therapy, the use of drugs, especially antibiotics, and a lack of exposure to the mother’s vaginal microbiota during natural birth. Changes in the intestinal microbiota are increasingly being identified in various diseases, starting in the early neonatal period into the adult period. Conclusions: In recent years, it has become more and more obvious that the components of the intestinal microbiota are crucial for the proper development of the immune system, and its disruption leads to disease.

Infant gut microbiota restoration: state of the art

The gut microbiota has a central role in the programming of the host's metabolism and immune function, with both immediate and long-term health consequences. Recent years have witnessed an accumulation of understanding of the process of the colonization and development of the gut microbiota in infants. The natural gut microbiota colonization during birth is frequently disrupted due to C-section birth or intrapartum or postpartum antibiotic exposure, and consequently aberrant gut microbiota development is common. On a positive note, research has shown that restoration of normal gut microbiota development is feasible. We discuss here the current understanding of the infant microbiota, provide an overview of the sources of disturbances, and critically evaluate the evidence on early life gut microbiota restoration for improved health outcomes by analyzing published data from infant gut microbiota restoration studies.