Host remodeling of the gut microbiome and metabolic changes during pregnancy.

Many of the immune and metabolic changes occurring during normal pregnancy also describe metabolic syndrome. Gut microbiota can cause symptoms of metabolic syndrome in nonpregnant hosts. Here, to explore their role in pregnancy, we characterized fecal bacteria of 91 pregnant women of varying prepregnancy BMIs and gestational diabetes status and their infants. Similarities between infant-mother microbiotas increased with children's age, and the infant microbiota was unaffected by mother's health status. Gut microbiota changed dramatically from first (T1) to third (T3) trimesters, with vast expansion of diversity between mothers, an overall increase in Proteobacteria and Actinobacteria, and reduced richness. T3 stool showed strongest signs of inflammation and energy loss; however, microbiome gene repertoires were constant between trimesters. When transferred to germ-free mice, T3 microbiota induced greater adiposity and insulin insensitivity compared to T1. Our findings indicate that host-microbial interactions that impact host metabolism can occur and may be beneficial in pregnancy.

Gestational diabetes is driven by microbiota-induced inflammation months before diagnosis.

OBJECTIVE: Gestational diabetes mellitus (GDM) is a condition in which women without diabetes are diagnosed with glucose intolerance during pregnancy, typically in the second or third trimester. Early diagnosis, along with a better understanding of its pathophysiology during the first trimester of pregnancy, may be effective in reducing incidence and associated short-term and long-term morbidities. DESIGN: We comprehensively profiled the gut microbiome, metabolome, inflammatory cytokines, nutrition and clinical records of 394 women during the first trimester of pregnancy, before GDM diagnosis. We then built a model that can predict GDM onset weeks before it is typically diagnosed. Further, we demonstrated the role of the microbiome in disease using faecal microbiota transplant (FMT) of first trimester samples from pregnant women across three unique cohorts. RESULTS: We found elevated levels of proinflammatory cytokines in women who later developed GDM, decreased faecal short-chain fatty acids and altered microbiome. We next confirmed that differences in GDM-associated microbial composition during the first trimester drove inflammation and insulin resistance more than 10 weeks prior to GDM diagnosis using FMT experiments. Following these observations, we used a machine learning approach to predict GDM based on first trimester clinical, microbial and inflammatory markers with high accuracy. CONCLUSION: GDM onset can be identified in the first trimester of pregnancy, earlier than currently accepted. Furthermore, the gut microbiome appears to play a role in inflammation-induced GDM pathogenesis, with interleukin-6 as a potential contributor to pathogenesis. Potential GDM markers, including microbiota, can serve as targets for early diagnostics and therapeutic intervention leading to prevention.

Evidence on postbiotics in infants and children.

PURPOSE OF REVIEW: The aim is to provide updated information on the concept of postbiotics and recent data on the efficacy of postbiotics for the prevention and treatment of childhood diseases. RECENT FINDINGS: In line with a recently proposed consensus definition, a postbiotic is 'a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host'. Although inanimate, postbiotics may exert health benefits. There are only limited data on infant formulas containing postbiotics, but they are well tolerated, support adequate growth and demonstrate no potential identifiable risks, although clinical benefits remain limited. Currently, there is only limited support for postbiotic use for treating diarrhoea and preventing common paediatric infectious diseases in young children. Given the limited evidence, sometimes with a high risk of bias, caution is justified. No data in older children and adolescents are available. SUMMARY: The consensus definition of postbiotics facilitates further research. As not all postbiotics are the same, the type of disease and specific postbiotic studied should be considered when choosing postbiotics for the prevention or treatment of childhood diseases. Additional studies are needed to assess disease conditions responsive to postbiotics. Mechanisms of action of postbiotics need to be evaluated and characterized.

Spontaneous preterm delivery is reflected in both early neonatal and maternal gut microbiota.

BACKGROUND: Aberrant gut microbiota composition in preterm neonates is linked to adverse health consequences. Little is known about the impact of perinatal factors or maternal gut microbiota on initial preterm gut colonization. METHODS: Fecal samples were collected from 55 preterm neonates (<35 gestational weeks), 51 mothers, and 25 full-term neonates during the first 3-4 postpartum days. Gut microbiota composition was assessed using 16S ribosomal RNA gene sequencing. RESULTS: Preterm neonates exhibited significantly lower gut microbiota alpha diversity and distinct beta diversity clustering compared to term neonates. Spontaneous preterm birth was associated with distinct initial gut microbiota beta diversity as compared to iatrogenic delivery. Gestational age or delivery mode had no impact on the preterm gut microbiota composition. The cause of preterm delivery was also reflected in the maternal gut microbiota composition. The contribution of maternal gut microbiota to initial preterm gut colonization was more pronounced after spontaneous delivery than iatrogenic delivery and not dependent on delivery mode. CONCLUSIONS: The initial preterm gut microbiota is distinct from term microbiota. Spontaneous preterm birth is reflected in the early neonatal and maternal gut microbiota. Transmission of gut microbes from mother to neonate is determined by spontaneous preterm delivery, but not by mode of birth. IMPACT: The initial gut microbiota in preterm neonates is distinct from those born full term. Spontaneous preterm birth is associated with changes in the gut microbiota composition of both preterm neonates and their mothers. The contribution of the maternal gut microbiota to initial neonatal gut colonization was more pronounced after spontaneous preterm delivery as compared to iatrogenic preterm delivery and not dependent on delivery mode. Our study provides new evidence regarding the early gut colonization patterns in preterm infants. Altered preterm gut microbiota has been linked to adverse health consequences and may provide a target for early intervention.

The Microbiota and Malnutrition: Impact of Nutritional Status During Early Life.

According to the developmental origins of health and disease hypothesis, our health is determined by events experienced in utero and during early infancy. Indeed, both our prenatal and postnatal nutrition conditions have an impact on the initial architecture and activity of our microbiota. Recent evidence has underlined the importance of the composition of the early gut microbiota in relation to malnutrition, whether it be undernutrition or overnutrition, that is, in terms of both stunted and overweight development. It remains unclear how early microbial contact is linked to the risk of disease, as well as whether alterations in the microbiome underlie the pathogenesis of malnutrition or are merely the end result of it, which indicates that thequestion of causality must urgently be answered. This review provides information on the complex interaction between the microbiota and nutrition during the first 1,000 days of life, taking into account the impact of both undernutrition and overnutrition on the microbiota and on infants' health outcomes in the short- and long-term.

Mycobiome Profiles in Breast Milk from Healthy Women Depend on Mode of Delivery, Geographic Location, and Interaction with Bacteria.

Recent studies report the presence of fungal species in breast milk of healthy mothers, suggesting a potential role in infant mycobiome development. In the present work, we aimed to determine whether the healthy human breast milk mycobiota is influenced by geographical location and mode of delivery, as well as to investigate its interaction with bacterial profiles in the same samples. A total of 80 mature breast milk samples from 4 different countries were analyzed by Illumina sequencing of the internal transcribed spacer 1 (ITS1) region, joining the 18S and 5.8S regions of the fungal rRNA region. Basidiomycota and Ascomycota were found to be the dominant phyla, with Malassezia and Davidiella being the most prevalent genera across countries. A core formed by Malassezia, Davidiella, Sistotrema, and Penicillium was shared in the milk samples from the different origins, although specific shifts in mycobiome composition were associated with geographic location and delivery mode. The presence of fungi in the breast milk samples was further confirmed by culture and isolate characterization, and fungal loads were estimated by quantitative PCR (qPCR) targeting the fungal ITS1 region. Cooccurrence network analysis of bacteria and fungi showed complex interactions that were influenced by geographical location, mode of delivery, maternal age, and pregestational body mass index. The presence of a breast milk mycobiome was confirmed in all samples analyzed, regardless of the geographic origin.IMPORTANCE During recent years, human breast milk has been documented as a potential source of bacteria for the newborn. Recently, we have reported the presence of fungi in breast milk from healthy mothers. It is well known that environmental and perinatal factors can affect milk bacteria; however, the impact on milk fungi is still unknown. The current report describes fungal communities (mycobiota) in breast milk samples across different geographic locations and the influence of the mode of delivery. We also provide novel insights on bacterium-fungus interactions, taking into account environmental and perinatal factors. We identified a core of four genera shared across locations, consisting of Malassezia, Davidiella, Sistotrema, and Penicillium, which have been reported to be present in the infant gut. Our data confirm the presence of fungi in breast milk across continents and support the potential role of breast milk in the initial seeding of fungal species in the infant gut.

IL-10 suppresses TNF-α-induced expression of human aromatase gene in mammary adipose tissue.

White adipose tissue inflammation is linked with increased aromatase gene expression and estrogen production, a major risk factor for breast cancer in obese postmenopausal women. TNF-α, a proinflammatory cytokine, is a key driver of aromatase promoter I.4-mediated expression in adipose tissue. In this study, we have shown that IL-10, an anti-inflammatory cytokine, suppressed both TNF-α-stimulated human aromatase reporter-luciferase (hARO-Luc) expression in mouse bone marrow mesenchymal stromal cells and aromatase gene expression in human breast adipose stromal cells (ASCs). IL-10 blocked TNF-α-stimulated ERK1/2 activation in ASCs, suggesting an inhibitory effect through the MAPK signaling pathway. The links among obesity, IL-10, and aromatase were confirmed in ovariectomized (OVX) hARO-Luc mice, where increased adiposity was associated with upregulation of aromatase reporter activity and reduced IL-10 level in the mammary fat pad. OVX mice also exhibited changes in gut microbiota, similar to that in obese women, indicating altered immune function. In summary, our results suggest that increased adiposity, induced by the lack of ovarian hormones, results in enhanced expression of aromatase in mammary adipose tissue, mediated by reduction in local IL-10. These findings may bring new insights into the mechanisms involved in the development of postmenopausal breast cancer, as well as novel approaches for prevention.-Martínez-Chacón, G., Brown, K. A., Docanto, M. M., Kumar, H., Salminen, S., Saarinen, N., Mäkelä, S. IL-10 suppresses TNF-α-induced expression of human aromatase gene in mammary adipose tissue.

The impact of probiotic supplementation during pregnancy on DNA methylation of obesity-related genes in mothers and their children.

PURPOSE: Dietary supplementation with probiotics during pregnancy has been suggested to decrease the risk for obesity in women after delivery and to minimize excessive weight gain in their children. Epigenetic DNA methylation has been proposed to impact on gene activity, thereby providing a plausible molecular mechanism for a broad range of biological processes and diseases. This pilot study aimed to evaluate whether probiotic supplementation during pregnancy could modify the DNA methylation status of the promoters of obesity and weight gain-related genes in mothers and their children. METHODS: A sample of 15 pregnant women was taken from a prospective, randomized mother and infant nutrition and probiotic study. Seven women received the probiotic supplementation and eight served as controls. The women's and their children's DNA methylation status of obesity (623 genes) and weight gain-related (433) gene promoters were analyzed from blood samples at the mean of 9.8 months (range 6.1-12.7 months) postpartum. RESULTS: Probiotic supplementation led to significantly decreased levels of DNA methylation in 37 gene promoters and increased levels of DNA methylation in one gene promoter in women. In their children, 68 gene promoters were significantly affected consistently with a lower level of DNA methylation in the probiotic group. CONCLUSIONS: On the basis of our pilot study, we suggest that probiotic supplementation during pregnancy may affect the DNA methylation status of certain promoters of obesity and weight gain-related genes both in mothers and their children, thereby providing a potential mechanism for long-lasting health effects.

Dysbiosis in Snoring Children: An Interlink to Comorbidities?

BACKGROUND AND OBJECTIVES: Early microbial colonization has a key impact on infant health through nutritional, immunological, and metabolic programming. The origin of child snoring is multifactorial and complex, and may thereby also generate long-term health problems. The link between child snoring and gut microbes remains unclear, although indirect evidence exists regarding this relationship. This study aimed to characterize the connection between gut microbiota and child snoring. METHODS: In a prospective, observational CHILD-SLEEP birth cohort study, gut microbiota in a subcohort of 43 of these children at 2 years of life was profiled with 16S ribosomal RNA gene amplicon sequencing. RESULTS: A higher abundance of the Proteobacteria phylum, the Enterobacteriaceae family, and Erysipelotrichaceae family, as well as a higher ratio of Firmicutes to Bacteroidetes were detected in snorers as compared to controls. Furthermore, snorers showed significantly lower microbial diversity and richness than non-snorers. CONCLUSIONS: The snoring children manifest different gut microbiota as compared with healthy children. Considering that snoring and sleep disorders can be a source of long-term consequences, including cardiovascular, metabolic, immunological, neurocognitive and behavioral consequences, our results proposes early microbiota as a new treatment target.

Shaping Microbiota During the First 1000 Days of Life.

The data obtained in prior studies suggest that early microbial exposition begins prior to conception and gestation. Given that the host-microbe interaction is shaped by the immune system response, it is important to understand the key immune system-microbiota relationship during the period from conception to the first years of life. The present work summarizes the available evidence concerning early microbiota exposure within the male and the female reproductive tracts at the point of conception and during gestation, focusing on the potential impact on infant development during the first 1000 days of life. Furthermore, we conclude that some dietary strategies including specific probiotics could become potentially valuable tools to modulate the gut microbiota during this early critical window of opportunity for targeted health outcomes throughout the entire lifespan.

Fructophilic Lactic Acid Bacteria, a Unique Group of Fructose-Fermenting Microbes.

Fructophilic lactic acid bacteria (FLAB) are a recently discovered group, consisting of a few Fructobacillus and Lactobacillus species. Because of their unique characteristics, including poor growth on glucose and preference of oxygen, they are regarded as "unconventional" lactic acid bacteria (LAB). Their unusual growth characteristics are due to an incomplete gene encoding a bifunctional alcohol/acetaldehyde dehydrogenase (adhE). This results in the imbalance of NAD/NADH and the requirement of additional electron acceptors to metabolize glucose. Oxygen, fructose, and pyruvate are used as electron acceptors. FLAB have significantly fewer genes for carbohydrate metabolism than other LAB, especially due to the lack of complete phosphotransferase system (PTS) transporters. They have been isolated from fructose-rich environments, including flowers, fruits, fermented fruits, and the guts of insects that feed on plants rich in fructose, and are separated into two groups on the basis of their habitats. One group is associated with flowers, grapes, wines, and insects, and the second group is associated with ripe fruits and fruit fermentations. Species associated with insects may play a role in the health of their host and are regarded as suitable vectors for paratransgenesis in honey bees. Besides their impact on insect health, FLAB may be promising candidates for the promotion of human health. Further studies are required to explore their beneficial properties in animals and humans and their applications in the food industry.

Increase in serum Interleukin-10 does not alleviate pro-inflammatory MCP-1 production in obese pregnancies.

Maternal cytokine profiles during pregnancy are characterized by significant deviations, varying substantially between gestational time points and tissues. Obesity, in turn, is linked with low-grade inflammation in adipose tissue and increased concentrations of systemic inflammatory mediators. However, the balance of pro- and anti-inflammatory cytokines in obese pregnancy has remained elusive. In view of the demonstrations that the obesity is a global epidemic in the population at reproductive age with a strong intergenerational impact, we investigated the relation of gestational immune adaptations and obesity-induced inflammation. We found a significant decrease in systemic IL-1ß and MCP-1 concentration from 1st to 3rd trimester of pregnancy while IL-10 concentration increased, respectively. However, in obese pregnancies this reduction of pro-inflammatory mediators was not detected. This may constitute an additional risk factor in obese pregnancies in which the concentration of MCP-1 is already upregulated compared to normal weight mothers.

The ability of human intestinal anaerobes to metabolize different oligosaccharides: Novel means for microbiota modulation?

Prebiotic oligosaccharides are known to have significant impacts on gut microbiota and are thus widely used to program healthy microbiota composition and activity from infants to the elderly. Bifidobacteria and lactobacilli are among the major target microorganisms of oligosaccharides, but the metabolic properties of oligosaccharides in other predominant gut microbes have not been well characterized. In the present study, we demonstrated the metabolic properties of six oligosaccharides in 31 key gut anaerobes. Bifidobacteria readily metabolized fructooligosaccharide (FOSs) with degree of polymerization (DP) 3, i.e. 1-kestose, but several strains used did not actively metabolize FOSs with DP4 and DP5, i.e. nystose and fructosylnystose. Akkermansia muciniphila, a potential new probiotic against obesity, did not show significant growth with any of the oligosaccharides tested. The butyrate producer Anaerostipes caccae grew well on 1-kestose but poorly on FOS mixtures, whereas it contained 1-kestose at 30%. Bacteroides-Parabacteroides group species were separated into two groups based on oligosaccharide metabolic properties. One group metabolized well most of the oligosaccharides tested, but the others metabolized only 1 or 2 selected oligosaccharides. Oligosaccharide profiles after culturing revealed that Bifidobacterium spp. preferentially metabolized shorter oligosaccharides (DP3) in the mixtures, whereas Bacteroides-Parabacteroides spp. did not show oligosaccharide selectivity for metabolism or rather preferred longer oligosaccharides (>DP4). The fermentation profiles indicated specific links between the microbial end-products and specific gut microbes. Available carbohydrates had a significant impact on the accumulation of amino acid-derived bacterial metabolites (i.e. phenol, p-cresol, indole and skatole) and short chain fatty acids. The results assist in predicting the impact of oligosaccharides in human intervention and gut microbiota modulation.

Long-term safety and efficacy of perinatal probiotic intervention: Evidence from a follow-up study of four randomized, double-blind, placebo-controlled trials.

BACKGROUND: Societies worldwide are faced with a progressive increase in immune-mediated health problems such as allergic, autoimmune, and inflammatory diseases, as well as obesity. Perinatal administration of specific probiotic bacteria is an attractive approach in reducing the risk of these conditions, but long-term efficacy and safety data are lacking. The aim here was to evaluate the clinical benefit and long-term safety of specific probiotics administered during the perinatal period. METHODS: The probiotic strains used were Lactobacillus rhamnosus GG, Bifidobacterium lactis Bb-12, Lactobacillus paracasei ST11, and Bifidobacterium longum BL999. The children involved have subsequently undergone prospective long-term follow-up. In addition to physical examination, data were collected by structured questionnaires on non-communicable diseases and continued probiotic use, and growth data from welfare clinics and school nurses. RESULTS: Altogether 303 mother-infant pairs were included in the analysis. Seventy-six of 163 (47%) children receiving perinatal probiotics had developed allergic disease compared with 79 of 140 (56%) receiving placebo (OR 0.67, 95% confidence intervals [CI] 0.43-1.06, p = 0.09). Fifty-nine of 133 (44%) children receiving L. rhamnosus GG perinatally had developed allergic disease, OR 0.62, 95% CI 0.38-0.99, p = 0.047, as compared to placebo. We found no differences in growth or non-communicable disease prevalence between children receiving perinatally probiotics or placebo. CONCLUSIONS: Perinatal probiotic administration is safe in long-term follow-up. Children receiving L. rhamnosus GG perinatally tended to have decreased allergy prevalence.

Probiotics modulate gut microbiota and health status in Japanese cedar pollinosis patients during the pollen season.

BACKGROUND: Japanese cedar pollinosis (JCP) is a challenging public health problem in Japan. Altered gut microbiota is associated with several diseases, including allergic diseases. However, only a few studies have focused on JCP and the underlying mechanisms for probiotic effects remain unclear. In addition, this study is the first observation of the correlation between the gut microbiota and blood lipid in JCP. METHODS: Faecal samples from JCP subjects were collected before and after treatment with (n = 14) and without (n = 11) LGG-TMC0356-fermented milk for 10 weeks. Gut microbiota composition was characterized from faecal DNA using sequencing of 16S rRNA genes. RESULTS: 16S rRNA-based operational taxonomic unit clustering of the microbiota revealed that LGG-TMC0356-fermented milk significantly altered gut microbiota after 10 weeks of milk consumption, and eight dominant genera of microbes were detected. During the JCP season, the Bacteroidetes/Firmicutes ratio, when compared to baseline, was significantly decreased in subjects at end of the study. Bacteroidetes showed positive correlation with LDL- and HDL-cholesterol levels, whereas Firmicutes showed negative correlation with total cholesterol, LDL- and HDL- cholesterol. CONCLUSIONS: The altered gut microbiota through supplementation of fermented milk containing the study probiotics may be a prospective target for protection against JCP, with beneficial effects on blood lipid levels.

Infantile Colic Is Associated With Low-grade Systemic Inflammation.

OBJECTIVES: Dysbiosis, an imbalance in the taxonomic composition of the gut bacteria occurring during the critical stages of development, induces lasting shifts in the immunological and metabolic phenotype if accompanied by an inflammatory response. Because altered gut microbiota and successful treatment with probiotics have both been demonstrated in cases of colic, we hypothesized here that infants with colic might have low-grade inflammation. METHODS: In 28 infants with colic and in 12 healthy controls at the age of 1 month, we measured the following serum immunological biomarkers: cytokines interleukin 1ß (IL-1ß); IL-6; IL-10; tumor necrosis factor α; interferon γ (IFN-γ); chemokines IL-8; monocyte chemotactic protein-1 (MCP-1); macrophage inflammatory protein 1ß (MIP-1ß) and chemokine (C-X-C motif) ligand 16; and intestinal fatty acid-binding protein, a biomarker of enterocyte damage and zonulin, a biomarker of intestinal permeability. In addition, intestinal microbiota composition was correlated with immunological biomarkers. RESULTS: Infants with colic had increased concentrations of IL-8, MCP-1, and MIP-1ß in serum as compared with healthy children. All the other immunological biomarkers were comparable between the groups. Fecal levels of Clostridium leptum correlated negatively with the proinflammatory markers MCP-1 (r = -0.44, P = 0.02), MIP-1ß (r = -0.43, P = 0.02), and tumor necrosis factor α (r = -0.38, P = 0.04). In addition, C coccoides group levels correlated negatively with MCP-1 (r = -0.43, P = 0.02) and Bifidobacterium breve levels positively with chemokine (C-X-C motif) ligand 16 (r = 0.38, P = 0.04). CONCLUSIONS: In addition to gut microbiota alterations, colic in infants is associated with low-grade systemic inflammation. Specific bacterial species beyond conventional probiotics may have anti-inflammatory properties that may help to modulate microbiota and alleviate colic-related inflammation.

Lipid-based Nutrient Supplements Do Not Affect Gut Bifidobacterium Microbiota in Malawian Infants: A Randomized Trial.

OBJECTIVES: The aim of the study was to assess the effect of nutritional supplementation with lipid-based nutrient supplements (LNS) and corn-soy blend flour on Bifidobacterium and Staphylococcus aureus gut microbiota composition in Malawian infants. In addition, the microbiota changes over time were characterized in the study infants. METHODS: Healthy 6-month-old Malawian infants were randomly assigned to 1 of 4 intervention schemes for a 6-month period. Infants in the control group were not provided with any supplementary food. Infants in other 3 groups received either micronutrient-fortified corn-soy blend, micronutrient-fortified LNS with milk protein base, or micronutrient-fortified LNS with soy protein base between 6 and 12 months of age. Fecal bifidobacteria and S aureus gut microbiota at 6 and 12 months of age were analyzed by quantitative real-time polymerase chain reaction method. RESULTS: There was no difference in change in bacterial prevalence or counts between the intervention groups during the 6-month study period. When looking at the total study population, higher counts of total bacteria (P = 0.028), Bifidobacterium genus (P = 0.027), B catenulatum (P = 0.031), and lower counts of B infantis (P < 0.001), B lactis (P < 0.001), B longum (P < 0.001), and S aureus (P < 0.001) were detected in the children's stools at 12 months rather than at 6 months of age. CONCLUSIONS: The dietary supplementation did not have an effect on the Bifidobacterium and S aureus microbiota composition of the study infants. The fecal bifidobacterial diversity of the infants, however, changed toward a more adult-like microbiota profile within the observed time.

Breast Milk Polyamines and Microbiota Interactions: Impact of Mode of Delivery and Geographical Location.

BACKGROUND/AIMS: The aim of the present study was to identify and quantify the polyamine levels in human milk obtained from different countries and through different modes of delivery, and to investigate their association with breast milk microbes. METHODS: Mature breast milk samples were obtained from 78 healthy mothers after 1 month of lactation from 4 different geographical locations: Finland, Spain (Europe); South Africa (Africa); and China (Asia). Polyamines were determined using HPLC after dansyl derivatization and milk microbiota was obtained by 16S rRNA gene sequencing. RESULTS: The mean values of polyamines in breast milk were 70.0, 424.2, and 610.0 nmol/dL for putrescine, spermidine and spermine, respectively, and 1,170.9 nmol/dL of total polyamines. The levels of putrescine were significantly higher in Spain (p < 0.05) and spermidine levels were significantly higher in Finland (p < 0.05) compared with other countries. Cesarean delivery had an impact on polyamine levels and it was related to an increase in the putrescine concentration being significant in Spanish samples (p < 0.01). Furthermore, putrescine levels were correlated positively with Gammaproteobacteria (r = 0.46, p < 0.001), especially with Pseudomonas fragi (r = 0.40, p < 0.001). CONCLUSIONS: The results demonstrate significant effect of geographical variations in human milk polyamine concentrations, being correlated with human milk microbiota composition. These differences may have an impact on infant development during lactation.