Investigating prenatal and perinatal factors on meconium microbiota: a systematic review and cohort study.

BACKGROUND: The first-pass meconium has been suggested as a proxy for the fetal gut microbiota because it is formed in utero. This systematic review and cohort study investigated how pre- and perinatal factors influence the composition of the meconium microbiota. METHODS: We performed the systematic review using Covidence by searching PubMed, Scopus, and Web of Science databases with the search terms "meconium microbiome" and "meconium microbiota". In the cohort study, we performed 16 S rRNA gene sequencing on 393 meconium samples and analyzed the sequencing data using QIIME2. RESULTS: Our systematic review identified 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition in relation to subsequent health of infants but gave only limited comparative evidence regarding factors related to the composition of the meconium microbiota. The cohort study pointed to a low-biomass microbiota consisting of the phyla Firmicutes, Proteobacteria and Actinobacteriota and the genera Staphylococcus, Escherichia-Shigella and Lactobacillus, and indicated that immediate perinatal factors affected the composition of the meconium microbiota more than did prenatal factors. CONCLUSIONS: This finding supports the idea that the meconium microbiota mostly starts developing during delivery. IMPACT: It is unclear when the first-pass meconium microbiota develops, and what are the sources of the colonization. In this systematic review, we found 69 studies exploring prenatal factors, immediate perinatal factors, and microbial composition relative to subsequent health of infants, but there was no consensus on the factors affecting the meconium microbiota development. In this cohort study, immediate perinatal factors markedly affected the meconium microbiota development while prenatal factors had little effect on it. As the meconium microbiota composition was influenced by immediate perinatal factors, the present study supports the idea that the initial gut microbiota develops mainly during delivery.

Maternal microbiota communicates with the fetus through microbiota-derived extracellular vesicles.

BACKGROUND: Reports regarding the presence of bacteria in the fetal environment remain limited and controversial. Recently, extracellular vesicles secreted by the human gut microbiota have emerged as a novel mechanism for host-microbiota interaction. We aimed to investigate the presence of bacterial extracellular vesicles in the fetal environment during healthy pregnancies and determine whether extracellular vesicles derived from the gut microbiota can cross biological barriers to reach the fetus. RESULTS: Bacterial extracellular vesicles were detectable in the amniotic fluid of healthy pregnant women, exhibiting similarities to extracellular vesicles found in the maternal gut microbiota. In pregnant mice, extracellular vesicles derived from human maternal gut microbiota were found to reach the intra-amniotic space. CONCLUSIONS: Our findings reveal maternal microbiota-derived extracellular vesicles as an interaction mechanism between the maternal microbiota and fetus, potentially playing a pivotal role in priming the prenatal immune system for gut colonization after birth. Video Abstract.

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.

Delivery Mode and Perinatal Antibiotics Influence the Infant Gut Bacteriome and Mycobiome: A Network Analysis.

Both exposure to antibiotics at birth and delivery via Caesarean section influence the gut bacteriome's development in infants. Using 16S rRNA and internal transcribed spacer sequencing on the Ion Torrent platform, we employed network analysis to investigate the bacterial and fungal interkingdom relationships in the gut microbiome from birth to age 18 months in a prospective cohort study of 140 infants. The gut microbiome at ages six and 18 months revealed distinctive microbial interactions, including both positive and negative associations between bacterial and fungal genera in the gut ecosystem. Perinatal factors, delivery mode and intrapartum antibiotic exposure affected the associations between bacterial and fungal species. In infants exposed and unexposed to perinatal antibiotics, the gut microbiome formed distinct networks for the bacteriome and mycobiome. The fungi Saccharomyces, Trichosporon, Pezoloma, Cystofilobasidium, Rigidoporus and Fomitopsis were strongly associated with exposure to antibiotics at birth. Hyaloscypha, Trichosporon, Fomitopsis and Vishniacozyma were strongly associated with the control group that was not exposed to antibiotics. Five distinct networks were formed according to delivery mode. The present study confirms that bacteria and fungi clearly interact in the infant gut ecosystem. Furthermore, perinatal factors appear to influence the relationships between bacteria and fungi in the developing gut microbiome.

Development of gut mycobiome in infants and young children: a prospective cohort study.

BACKGROUND: The composition of the gut fungal microbiome, mycobiome, is likely associated with human health. Yet, the development of gut mycobiome is poorly understood in infants and children. Here we investigate how perinatal events influence the development of gut mycobiome. METHODS: In this prospective cohort study of 140 infants, we used ITS gene sequencing of fecal samples from birth to the age of 18 months. We compared gut mycobiome composition according to delivery mode and exposure to intrapartum antibiotics during vaginal delivery. RESULTS: At birth, gut mycobiome were dominated by the genus Candida, at 6-month stool samples by Malassezia and Cystofilobasidium, and the 18-month stool samples by Trichosporon and unidentified fungi. Perinatal factors altered mycobiome. At 18 months, gut mycobiome of infants born vaginally consisted mostly of Trichosporon (32%) and unidentified fungi (31%), while those born via Cesarean section delivery samples had mycobiome dominated by Saccharomyces (50%). At the age of 18 months, those exposed to intrapartum antibiotics had mycobiome dominated by Trichosporon (66%) not seen in those unexposed to antibiotics. CONCLUSIONS: Delivery mode and exposure to intrapartum antibiotic prophylaxis were markedly associated with gut mycobiome composition from birth to 18 months of age. IMPACT: The composition of the gut mycobiome is likely associated with human health. Yet, the development of gut mycobiome is poorly understood in infants and children. In this prospective cohort study, delivery mode and exposure to intrapartum antibiotic prophylaxis were markedly associated with gut mycobiome composition from birth to 18 months of age. The impact of intrapartum antibiotic prophylaxis on fungal microbiome in vaginally born infants, previously shown to influence gut bacteriome composition, may be explained by the interaction between bacteria and fungi. Gut mycobiome composition likely deserves further investigation in relation to gut microbiome and health in children.

Cranberry-lingonberry juice affects the gut and urinary microbiome in children - a randomized controlled trial.

The mechanism by which cranberry-lingonberry juice (CLJ) prevents urinary tract infections (UTI) in children remains unknown. We hypothesized that it alters the composition of the gut or urinary microbiome. Altogether, 113 children with UTIs were randomly allocated to drink either CLJ or a placebo juice for 6 months. We collected urinary samples at 3 months and fecal samples at 3, 6 and 12 months and used next-generation sequencing of the bacterial 16S gene. The children who consumed CLJ had a lower abundance of Proteobacteria (p = 0.03) and a higher abundance of Firmicutes phylum (p = 0.04) in their urinary microbiome at 3 months than did those in the placebo group. The abundance of Escherichia coli in the urinary microbiome was 6% in the CLJ group and 13% in the placebo group (p = 0.42). In the gut microbiome the abundance of Actinobacteria at 3 and 12 months was higher in the children receiving CLJ. The diversity of the urinary and gut microbiome did not differ between the groups. The children drinking CLJ had a different urinary and gut microbiome from those receiving a placebo juice. A healthy urinary microbiome may be important in preventing UTIs in children.

Bacterial extracellular vesicles in the microbiome of first-pass meconium in newborn infants.

BACKGROUND: Bacterial extracellular vesicles (EVs) are more likely to cross biological barriers than whole-cell bacteria. We previously observed EV-sized particles by electron microscopy in the first-pass meconium of newborn infants. We hypothesized that EVs may be of bacterial origin and represent a novel entity in the human microbiome during fetal and perinatal periods. METHODS: We extracted EVs from first-pass meconium samples of 17 newborn infants and performed bacterial 16S rRNA gene sequencing of the vesicles. We compared the EV content from the meconium samples of infants based on the delivery mode, and in vaginal delivery samples, based on the usage of intrapartum antibiotics. RESULTS: We found bacterial EVs in all first-pass meconium samples. All EV samples had bacterial RNA. Most of the phyla present in the samples were Firmicutes (62%), Actinobacteriota (18%), Proteobacteria (10%), and Bacteroidota (7.3%). The most abundant genera were Streptococcus (21%) and Staphylococcus (17%). The differences between the delivery mode and exposure to antibiotics were not statistically significant. CONCLUSIONS: Bacterial EVs were present in the first-pass meconium of newborn infants. Bacterial EVs may represent an important novel feature of the gut microbiome during fetal and perinatal periods. IMPACT: We show that bacterial extracellular vesicles are present in the microbiome of first-pass meconium in newborn infants. This is a novel finding. To our knowledge, this is the first study to report the presence of bacterial extracellular vesicles in the gut microbiome during fetal and perinatal periods. This finding is important because bacterial extracellular vesicles are more likely to cross biological barriers than whole-cell bacteria. Thus, the early gut microbiome may potentially interact with the host through bacterial EVs.

Microbiota of the first-pass meconium and subsequent atopic and allergic disorders in children.

BACKGROUND: Some cohort studies have suggested that gut microbiota composition is associated with allergic diseases in children. The microbiota of the first-pass meconium, which forms before birth, represents the first gut microbiota that is easily available for research and little is known about any relationship with allergic disease development. OBJECTIVE: We investigated whether the bacterial composition of the first-pass meconium is associated with the development of allergic diseases before 4 years of age. METHODS: Prospective birth cohort study. Bacterial composition of first-pass meconium was analysed using bacterial 16S rRNA gene amplicon sequencing. Atopic and allergic diseases were evaluated via online survey or telephone to age 4 years, based on the International Study of Asthma and Allergies in Childhood questionnaire. RESULTS: During a 6-week period in 2014, 312 children were born at the Central Finland Central Hospital. Meconium was collected from 212 at a mean of 8-hour age. Outcome data at 4 years were available for 177 (83%) children, and 159 of these had sufficient amplification of bacterial DNA in meconium. Meconium microbiota composition, including diversity indices and relative abundances of the main phyla and genera, was not associated with subsequent atopic eczema, wheezing or cow's milk allergy. Principal components analysis did not identify any clustering of the meconium microbiomes of children with respect to wheezing or cow's milk allergy. CONCLUSIONS: We found no evidence that gut microbiota composition of first-pass meconium is associated with atopic manifestations to age 4 years. However, larger studies are needed to fully exclude a relationship.

Antibiotics at birth and later antibiotic courses: effects on gut microbiota.

BACKGROUND: Intrapartum antibiotic prophylaxis (IAP) is widely used, but the evidence of the long-term effects on the gut microbiota and subsequent health of children is limited. Here, we compared the impacts of perinatal antibiotic exposure and later courses of antibiotic courses on gut microbiota. METHODS: This was a prospective, controlled cohort study among 100 vaginally delivered infants with different perinatal antibiotic exposures: control (27), IAP (27), postnatal antibiotics (24), and IAP and postnatal antibiotics (22). At 1 year of age, we performed next-generation sequencing of the bacterial 16S ribosomal RNA gene of fecal samples. RESULTS: Exposure to the perinatal antibiotics had a clear impact on the gut microbiota. The abundance of the Bacteroidetes phylum was significantly higher in the control group, whereas the relative abundance of Escherichia coli was significantly lower in the control group. The impact of the perinatal antibiotics on the gut microbiota composition was greater than exposure to later courses of antibiotics (28% of participants). CONCLUSIONS: Perinatal antibiotic exposure had a marked impact on the gut microbiota at the age of 1 year. The timing of the antibiotic exposure appears to be the critical factor for the changes observed in the gut microbiota. IMPACT: Infants are commonly exposed to IAP and postnatal antibiotics, and later to courses of antibiotics during the first year of life. Perinatal antibiotics have been associated with an altered gut microbiota during the first months of life, whereas the evidence regarding the long-term impact is more limited. Perinatal antibiotic exposure had a marked impact on the infant's gut microbiota at 1 year of age. Impact of the perinatal antibiotics on the gut microbiota composition was greater than that of the later courses of antibiotics at the age of 1 year.

Presence of distinctive microbiome in the first-pass meconium of newborn infants.

We critically evaluated the fetal microbiome concept in 44 neonates with placenta, amniotic fluid, and first-pass meconium samples. Placental histology showed no signs of inflammation. Meconium samples were more often bacterial culture positive after vaginal delivery. In next-generation sequencing of the bacterial 16S gene, before and after removal of extracellular and PCR contaminant DNA, the median number of reads was low in placenta (48) and amniotic fluid (46) and high in meconium samples (14,556 C-section, 24,860 vaginal). In electron microscopy, meconium samples showed extracellular vesicles. Utilizing the analysis of composition of microbiomes (ANCOM) against water, meconium samples had a higher relative abundance of Firmicutes, Lactobacillus, Streptococcus, and Escherichia-Shigella. Our results did not support the existence of the placenta and amniotic fluid microbiota in healthy pregnancies. The first-pass meconium samples, formed in utero, appeared to harbor a microbiome that may be explained by perinatal colonization or intrauterine colonization via bacterial extracellular vesicles.

Delivery mode and perinatal antibiotics influence the predicted metabolic pathways of the gut microbiome.

Delivery mode and perinatal antibiotics influence gut microbiome composition in children. Most microbiome studies have used the sequencing of the bacterial 16S marker gene but have not reported the metabolic function of the gut microbiome, which may mediate biological effects on the host. Here, we used the PICRUSt2 bioinformatics tool to predict the functional profiles of the gut microbiome based on 16S sequencing in two child cohorts. Both Caesarean section and perinatal antibiotics markedly influenced the functional profiles of the gut microbiome at the age of 1 year. In machine learning analysis, bacterial fatty acid, phospholipid, and biotin biosynthesis were the most important pathways that differed according to delivery mode. Proteinogenic amino acid biosynthesis, carbohydrate degradation, pyrimidine deoxyribonucleotide and biotin biosynthesis were the most important pathways differing according to antibiotic exposure. Our study shows that both Caesarean section and perinatal antibiotics markedly influence the predicted metabolic profiles of the gut microbiome at the age of 1 year.

Vertical Transmission of Gut Microbiome and Antimicrobial Resistance Genes in Infants Exposed to Antibiotics at Birth.

Vertical transmission of maternal microbes is a major route for establishing the gut microbiome in newborns. The impact of perinatal antibiotics on vertical transmission of microbes and antimicrobial resistance is not well understood. Using a metagenomic approach, we analyzed the fecal samples from mothers and vaginally delivered infants from a control group (10 pairs) and a treatment group (10 pairs) receiving perinatal antibiotics. Antibiotic-usage had a significant impact on the main source of inoculum in the gut microbiome of newborns. The control group had significantly more species transmitted from mothers to infants (P = .03) than the antibiotic-treated group. Approximately 72% of the gut microbial population of infants at 3-7 days after birth in the control group was transmitted from their mothers, versus only 25% in the antibiotic-treated group. In conclusion, perinatal antibiotics markedly disturbed vertical transmission and changed the source of gut colonization towards horizontal transfer from the environment to the infants.

Impact of Streptococcus salivarius K12 on Nasopharyngeal and Saliva Microbiome: A Randomized Controlled Trial.

BACKGROUND: Probiotic lactobacilli have been ineffective in preventing acute otitis media. In contrast to lactobacilli, alpha-hemolytic streptococci belong to the core microbiome of nasopharynx. METHODS: We investigated the effects of Streptococcus salivarius K12 probiotic on the saliva and nasopharyngeal microbiome in 121 children attending daycare. Children were randomly allocated to receive oral K12 product for 1 month or no treatment. We obtained saliva and nasopharyngeal samples at study entry, at 1 and 2 months. The next-generation sequencing of the bacterial 16S gene was performed. RESULTS: After the intervention, the diversity of saliva or nasopharyngeal microbiome did not differ between groups. The proportion of children with any otopathogen did not differ between the groups. At 1 month, the abundance of otopathogens in nasopharynx was lower in K12 group compared with that in control children (34% vs. 55%, P = 0.037). When we compared each otopathogen separately, Moraxella was the only group lower in the treatment group. We could not verify the reduction of Moraxella when an alternative Human Oral Microbiome Database taxonomy database was used. In children receiving K12 product, the mean abundance of S. salivarius was greater in saliva after the intervention (0.9% vs. 2.0%, P = 0.009). CONCLUSIONS: The use of S. salivarius K12 probiotic appeared to be safe because it did not disrupt the normal microbiome in young children. Even though a short-term colonization of S. salivarius was observed in the saliva, the impact of S. salivarius K12 probiotic on the otopathogens in nasopharyngeal microbiome remained uncertain.

Microbiome of the first stool and overweight at age 3 years: A prospective cohort study.

BACKGROUND: Several reports have revealed that the first-pass meconium hosts a diverse microbiome, but its clinical significance is not known. OBJECTIVE: We designed a prospective population-based cohort study to evaluate whether the meconium microbiome predicts subsequent growth in children. METHODS: The study comprised 212 consecutive newborns with a meconium sample and a follow-up sample at 1 year of age. Trained nurses measured the children for weight and length using standardized techniques. We used next-generation sequencing of bacterial 16S rRNA gene and machine-learning approach for the analysis. RESULTS: The children with overweight at 3 years of age differed in their meconium microbiome from those with normal weight, having a higher proportion of Bacteroidetes phylum (29% vs 15%, P = .013). Using the machine-learning approach, the gut microbiome at birth predicted subsequent overweight with area under the curve 0.70 (SD 0.04). A lower proportion of Staphylococcus at birth was associated with greater length/height at 1 year (ß = -.68, P = .029) and 2 years of age (ß = -.74, P = .030). CONCLUSIONS: The microbiome of the first-pass meconium predicted subsequent overweight at the age of 3 years. The association between the gut microbiome and overweight appears to start already during pregnancy and at birth.

Tonsil Mycobiome in PFAPA (Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis) Syndrome: A Case-Control Study.

Periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome (PFAPA) is the most common periodic fever syndrome in children with unknown etiology, effectively treated with tonsillectomy. Earlier we have shown that tonsil microbiome is different in patients with PFAPA as compared to that in controls. Recently, fungal microbiome, mycobiome, has been linked to the pathogenesis of inflammatory diseases. We now investigated the role of mycobiome of tonsils in PFAPA. Random forest classification, a machine learning approach, was used for the analysis of mycobiome data. We examined tonsils from 30 children with PFAPA and 22 control children undergoing tonsillectomy for non-infectious reasons. We identified 103 amplicon sequence variants, mainly from two fungal phyla, Ascomycota and Basidiomycota. The mean relative abundance of Candida albicans in the tonsil mycobiome was 11% (95% CI: 19 to 27%) in cases and 3.4 % (95% CI: -0.8% to 8%) in controls, p =0.104. Mycobiome data showed no statistical difference in differentiating between PFAPA cases and controls compared to a random chance classifier (area under the curve (AUC) = 0.47, SD = 0.05, p = 0.809). In conclusion, in this controlled study, tonsillar mycobiome in children with PFAPA syndrome did not differ from that of the controls.

Interfacial Nanoparticle Complexation of Oppositely Charged Nanocelluloses into Functional Filaments with Conductive, Drug Release, or Antimicrobial Property.

Construction of colloidal nanoparticles (NPs) into advanced functional nanocomposites and hybrids with the predesigned hierarchical structure and high-performance is attractive, especially for natural biological nanomaterials, such as proteins and polysaccharides. Herein, a simple and sustainable approach called interfacial NP complexation (INC) was applied to construct diverse functional (conductive, drug-loaded, or antimicrobial) nanocomposite filaments from oppositely charged colloidal nanocelluloses. By incorporating different additives during the INC process, including multiwalled carbon nanotube, an antitumor drug (doxorubicin hydrochloride), and metal (silver) NPs (Ag NPs), high-performance functional continuous filaments were synthesized, and their potential applications in electronics, drug delivery, and antimicrobial materials were investigated, respectively. This novel INC method based on charged colloidal NPs opens new avenues for building various functional filaments for a diversity of end uses.

Impact of intrapartum and postnatal antibiotics on the gut microbiome and emergence of antimicrobial resistance in infants.

Altogether, 20-30% of women receive intrapartum antibiotic prophylaxis (IAP) to prevent sepsis in infants and 2-5% of newborn infants receive antibiotics due to suspected sepsis. Caesarean section has a long-term impact on the intestinal microbiome but the effects of perinatal antibiotics on gut microbiome in vaginally delivered infants are not well known. We compared the impact of IAP, postnatal antibiotics, or their combination on the gut microbiome and emergence of antimicrobial resistance in a controlled study of 149 newborn infants recruited within 24 hours after birth. We collected 659 fecal samples, including 426 daily samples from infants before discharge from the hospital and 111 follow-up samples at six months. Penicillin was mostly used for IAP and the combination of penicillin and aminoglycoside for postnatal treatment. Postnatal antibiotic groups received Lactobacillus reuteri probiotic. Newborn gut colonization differed in both IAP and postnatal antibiotics groups as compared to that in control group. The effect size of IAP was comparable to that caused by postnatal antibiotics. The observed differences were still present at six months and not prevented by lactobacilli consumption. Given the present clinical results, the impact of perinatal antibiotics on the subsequent health of newborn infants should be further evaluated.

Prevention of urinary catheter-associated infections by coating antimicrobial peptides from crowberry endophytes.

Urinary catheters are extensively used in hospitals, being responsible for about 75% of hospital-acquired infections. In this work, a de novo designed antimicrobial peptide (AMP) Chain201D was studied in the context of urinary catheter-associated infections. Chain201D showed excellent antimicrobial activity against relevant ATCC strains and clinical isolates of bacteria and yeast and demonstrated high stability in a wide range of temperatures, pH and salt concentrations. Moreover, the bactericidal activity of Chain201D immobilized on a model surface was studied against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), some of the most prevalent strains found in urinary catheter-associated infections. Chain201D was successfully tethered to ((1-mercapto-11-undecyl)-(tetra(ethylene glycol) (EG4)) terminated self-assembled monolayers (SAMs), (EG4-SAMs), activated by 1,1'-Carbonyldiimidazole (CDI) at different concentrations. Chain201D surfaces can bind and kill by contact a high percentage of adherent bacteria. These achievements are obtained without any peptide modification (for chemoselective conjugation) and without the use of a spacer. Moreover, increased amounts of immobilized AMP lead to higher numbers of adhered/dead bacteria, revealing a concentration-dependent behaviour and demonstrating that Chain201D has excellent potential for developing antimicrobial urinary catheters.

Fungi Originating From Tree Leaves Contribute to Fungal Diversity of Litter in Streams.

Biomass production and decomposition are key processes in ecology, where plants are primarily responsible for production and microbes act in decomposition. Trees harbor foliar microfungi living on and inside leaf tissues, epiphytes, and endophytes, respectively. Early researchers hypothesized that all fungal endophytes are parasites or latent saprophytes, which slowly colonize the leaf tissues for decomposition. While this has been proven for some strains in the terrestrial environment, it is not known whether foliar microfungi from terrestrial origin can survive or perform decomposition in the aquatic environment. On the other hand, aquatic hyphomycetes, fungi which decompose organic material in stream environments, have been suggested to have a plant-associated life phase. Our aim was to study how much the fungal communities of leaves and litter submerged in streams overlap. Ergosterol content on litter, which is an estimator of fungal biomass, was 5-14 times higher in submerged litter than in senescent leaves, indicating active fungal colonization. Leaves generally harbored a different microbiome prior to than after submergence in streams. The Chao1 richness was significantly higher (93.7 vs. 60.7, p = 0.004) and there were more observed operational taxonomic units (OTUs) (78.3 vs. 47.4, p = 0.004) in senescent leaves than in stream-immersed litter. There were more Leotiomycetes (9%, p = 0.014) in the litter. We identified a group of 35 fungi (65%) with both plant- and water-associated lifestyles. Of these, eight taxa had no previous references to water, such as lichenicolous fungi. Six OTUs were classified within Glomeromycota, known as obligate root symbionts with no previous records from leaves. Five members of Basidiomycota, which are rare in aquatic environments, were identified in the stream-immersed litter only. Overall, our study demonstrates that foliar microfungi contribute to fungal diversity in submerged litter.