The Influence of Different Maternal Microbial Communities on the Development of Infant Gut and Oral Microbiota.

Very few studies have analyzed how the composition of mother's microbiota affects the development of infant's gut and oral microbiota during the first months of life. Here, microbiota present in the mothers' gut, vagina, breast milk, oral cavity, and mammary areola were compared with the gut and oral microbiota of their infants over the first six months following birth. Samples were collected from the aforementioned body sites from seven mothers and nine infants at three different time points over a 6-month period. Each sample was analyzed with 16S rRNA gene sequencing. The gut microbiota of the infants harbored distinct microbial communities that had low similarity with the various maternal microbiota communities. In contrast, the oral microbiota of the infants exhibited high similarity with the microbiota of the mothers' breast milk, mammary areola and mouth. These results demonstrate that constant contact between microbial communities increases their similarity. A majority of the operational taxonomic units in infant gut and oral microbiota were also shared with the mothers' gut and oral communities, respectively. The disparity between the similarity and the proportion of the OTUs shared between infants' and mothers' gut microbiota might be related to lower diversity and therefore competition in infants' gut microbiota.

Differences in Gut Microbiota Between Atopic and Healthy Children.

Although gut microbiota has been studied relatively extensively in the context of allergic diseases, there have been several contradictions between these studies. By applying high-throughput sequencing, we aimed to analyze the differences in gut microbiota between atopic and healthy children at 5 and 12 years of age. 51 stool samples were collected from 14 atopic and 15 healthy children and analyzed with 454 pyrosequencing of the 16S rRNA gene. At the ages of 5 and 12 years, Bacteroides, Prevotella, and Dialister dominated gut microbiota in both atopic and healthy groups of children. Children in the atopic group had lower abundance and prevalence of Akkermansia in gut microbiota than their healthy counterparts. Thus, the composition of gut microbiota does not seem to be significantly different between atopic and healthy children, but lower abundance and prevalence of Akkermansia indicate that this bacterium may accompany or play a role in IgE-mediated atopic diseases.

The development of gut microbiota in critically ill extremely low birth weight infants assessed with 16S rRNA gene based sequencing.

OBJECTIVE: An increasing number of studies that are using high-throughput molecular methods are rapidly extending our knowledge of gut microbial colonization in preterm infants whose immaturity and requirement for extensive treatment may result in altered colonization process. We aimed to describe the profile of gut microbiota in 50 extremely low birth weight (<1200 g) critically ill infants at three different time points during the first two months of life by using 16S rRNA gene specific sequencing.   PATIENTS AND METHODS: Stool samples were collected at the age of one week, one month and two months. Bacterial community profiling was done using universal amplification of 16S rRNA gene and 454 pyrosequencing. RESULTS: The diversity of gut microbiota in preterm neonates in the first week of life was low but increased significantly over two months. The gut microbiota was dominated by facultative anaerobic bacteria (Staphylococcus spp. and Enterobacteriaceae) and lacked colonization with bacteria known to provide resistance against pathogens (Bacteroides, Bifidobacterium, and Lactobacillus) throughout the study. Colonization of Escherichia coli and uncultured Veillionella was positively correlated with maturity. Infants born to mothers with chorioamnionitis had significantly higher bacterial diversity than those without. CONCLUSIONS: High prevalence and abundance of potentially pathogenic Enterobacteriaceae and Staphylococcaceae with low prevalence and abundance of colonization resistance providing taxa bifidobacteria, Bacteroides and lactobacilli may lead to high infection risk via microbial translocation from the gut. Additionally, our data suggest that maternal chorioamnionitis may have an effect on the diversity of infants' gut microbiota; however, the mechanisms involved remain to be elucidated.

Characterization of the vaginal micro- and mycobiome in asymptomatic reproductive-age Estonian women.

The application of high-throughput sequencing methods has raised doubt in the concept of the uniform healthy vaginal microbiota consisting predominantly of lactobacilli by revealing the existence of more variable bacterial community composition. As this needs to be analyzed more extensively and there is little straightforward data regarding the vaginal mycobiome of asymptomatic women we aimed to define bacterial and fungal communities in vaginal samples from 494 asymptomatic, reproductive-age Estonian women. The composition of the vaginal microbiota was determined by amplifying bacterial 16S rRNA and fungal internal transcribed spacer-1 (ITS-1) regions and subsequently sequencing them using 454 Life Sciences pyrosequencing. We delineated five major bacterial community groups with distinctive diversity and species composition. Lactobacilli were among the most abundant bacteria in all groups, but also members of genus Gardnerella had high relative abundance in some of the groups. Microbial diversity increased with higher vaginal pH values, and was also higher when a malodorous discharge was present, indicating that some of the women who consider themselves healthy may potentially have asymptomatic bacterial vaginosis (BV). Our study is the first of its kind to analyze the mycobiome that colonizes the healthy vaginal environment using barcoded pyrosequencing technology. We observed 196 fungal operational taxonomic units (OTUs), including 16 OTUs of Candida spp., which is more diverse than previously recognized. However, assessing true fungal diversity was complicated because of the problems regarding the possible air-borne contamination and bioinformatics used for identification of fungal taxons as significant proportion of fungal sequences were assigned to unspecified OTUs.