The prevalence of gestational diabetes mellitus (GDM) is a global public health concern. The mechanism that leads to glucose tolerance beyond normal physiological levels to pathogenic conditions remains incompletely understood, and it is speculated that the maternal microbiome may play an important role. This study analyzes the gut microbiota composition in each trimester of weight-matched women with and without GDM and examines possible bacterial genera associations with GDM. This study followed 56 pregnant women with GDM and 59 without admitted to the outpatient clinic during their first/second or third trimester of gestation. They were submitted to a standardized questionnaire, dietary recalls, clinical examination, biological sample collection, and molecular profiling of fecal microbiota. Women with GDM were older and had a higher number of pregnancies than normal-tolerant ones. There was no difference in alpha diversity, and the groups did not differ regarding the overall microbiota structure. A higher abundance of Bacteroides in the GDM group was found. A positive correlation between Christensenellaceae and Intestinobacter abundances with one-hour post-challenge plasma glucose and a negative correlation between Enterococcus and two-hour plasma glucose levels were observed. Bifidobacterium and Peptococcus abundances were increased in the third gestational trimester for both groups. The gut microbiota composition was not dependent on the presence of GDM weight-matched women throughout gestation. However, some genera abundances showed associations with glucose metabolism. Our findings may therefore encourage a deeper understanding of physiological and pathophysiological changes in the microbiota throughout pregnancy, which could have further implications for diseases prevention.

Very low birth weight (VLBW) infants, mostly preterm, have many barriers to feeding directly from the mother’s breast, and need to be fed alternatively. Feeding is a major influencer in oral microbial colonization, and this colonization in early life is crucial for the promotion of human health. Therefore, this research aimed to observe the establishment of oral microbiome in VLBW infants during their first month of life through hospitalization, and to verify the impact caused by the implementation of oral diet on the colonization of these newborns. We included 23 newborns followed during hospitalization and analyzed saliva samples collected weekly, using 16S rRNA gene sequencing. We observed a significant decrease in richness and diversity and an increase in dominance over time (q-value < 0.05). The oral microbiome is highly dynamic during the first weeks of life, and beta diversity suggests a microbial succession in early life. The introduction of oral diet does not change the community structure, but affects the abundance, especially of Streptococcus. Our results indicate that although time is related to significant changes in the oral microbial profile, oral feeding benefits genera that will remain colonizers throughout the host’s life.

This study aimed to evaluate the intestinal microbiota development in the first week of life of preterm newborns (PTNB) treated at a public hospital in a municipality in the Brazilian Northeast. This is an observational, longitudinal, and descriptive study with 23 PTNBs. Two stool samples were collected from each neonate (fasting/meconium and seventh day of life) for stool microbiota analysis by 16S rRNA gene sequencing. The authors analyzed alpha diversity (Chao1, Shannon, and Simpson indices) and principal coordinates of beta diversity. Forty-six stool samples from 23 PTNBs were analyzed at the taxonomic level. Microbiota's development was dynamic with low diversity. The authors observed a statistical association with the genera Enterobacterales, Streptococcus, Bacteroides, Clostridium_sensu_stricto_1, Enterococcus, and Bifidobacterium in the fasting samples when compared to the day-7 samples. The genus Staphylococcus also dominated at both times. Dynamics were observed in the intestinal microbiota development, with an alpha diversity decrease in the stool samples collected at fasting/meconium and on the seventh day of life.