Profile of the oral microbiota from preconception to the third trimester of pregnancy and its association with oral hygiene practices

Consensus approach to differential abundance analysis detects few differences in the oral microbiome of pregnant women due to pre-existing type 2 diabetes mellitus

Oral microbiome dysbiosis has been proposed as a potential contributing factor to rising rates of diabetes in pregnancy, with oral health previously associated with an increased risk of numerous chronic diseases and complications in pregnancy, including gestational diabetes mellitus (GDM). However, whilst most studies examining the relationship between GDM and the oral microbiome identify significant differences, these differences are highly variable between studies. Additionally, no previous research has examined the oral microbiome of women with pre-existing type 2 diabetes mellitus (T2DM), which has greater risks of complications to both mother and baby. In this study, we compared the oral microbiome of 11 pregnant women with pre-existing T2DM with 28 pregnant normoglycaemic controls. We used shotgun metagenomic sequencing to examine buccal swab and saliva rinse samples at two time points between 26 and 38 weeks of gestation. To reduce variation caused by the choice of differential abundance analysis tool, we employed a consensus approach to identify differential taxa and pathways due to diabetes status. Differences were identified at the late time point only. In swab samples, there was increased Flavobacteriaceae, Capnocytophaga, Capnocytophaga gingivalis SGB2479, Capnocytophaga leadbetteri SGB2492 and Neisseria elongata SGB9447 abundance in T2DM as well as increased Shannon diversity and richness. In rinse samples, there was an increased abundance of Haemophilus, Pasteurellaceae, Pasteurellales and Proteobacteria. In contrast to studies of the oral microbiome in T2DM or GDM that use a single differential abundance analysis tool, our consensus approach identified few differences between pregnant women with and without T2DM.

Altered oral health and microbiota in drug-free patients with schizophrenia

BACKGROUND

The oral microbiota is associated with neuro-psychiatric disorders. However, there is presently inadequate comprehension regarding the correlation between schizophrenia and the oral microbiota. Moreover, patients with schizophrenia frequently exhibit poor oral health, potentially influencing research outcomes. Therefore, this study aims to investigate changes in the oral microbiota and oral health status in drug-free schizophrenia patients.

METHODS

Oral microbiota samples were collected from 50 drug-free patients with schizophrenia and 50 healthy controls (HCs). The downstream microbiota analysis was based on Illumina sequencing of the V3-V4 hypervariable region of the 16 S rRNA gene.

RESULTS

The alpha diversity of SCZ group is increased, such as the Shannon index (p < 0.001) and Simpson index (p = 0.004), while the community structure also displays variance compared to the HC group (p < 0.001). Key discriminative taxa were found in LEfSe analysis, including the phyla Fusobacteriota, Firmicutes, and Actinobacteriota. The differential taxa and microbial functions showed a strong correlation with clinical oral conditions. Further analysis demonstrated that models based on the entire oral microbiota effectively distinguished SCZ patients from HC (AUC = 0.97).

CONCLUSIONS

The significant changes in the microbiota of Drug-free SCZ patients appear to be closely associated with the poor oral environment.

The oral microbiota and its relationship to dental calculus and caries

OBJECTIVES

In this review, we provide an overview of the composition of the microbiota associated with these two dental pathologies, caries and tartar, highlighting the microbial profiles associated with each pathology.

DESIGN

This literature review was carried out by a manual search of two electronic databases, PubMed and Web of Science (WOS), using specific keywords to the two oral pathologies dental caries and calculus.

RESULTS

The oral microbial community is known for its complexity, and comprises hundreds of species of different micro-organisms. Many of them, under the influence of endogenous and exogenous factors, can play a role in the onset and development of oral pathologies. Analysis of the microbial profiles of caries and dental calculus revealed that Streptococcus mutans and Lactobacillus species are abundant in the oral microbiota associated with caries whereas their presence is less reported in dental calculus. However, the three pathogens known as the "red complex", namely Porphyromonas, Tannarella and Treponema, which are associated with the development of periodontal pathology, are strongly present in the dental calculus microbiome.

CONCLUSION

The microbiota composition associated with dental caries and calculus highlights specific microbial signatures for each of the two oral pathologies, underscoring their differences and microbiological complexity, while the possible relationship between the formation of dental calculus and the development of caries remains unclear.

Metabarcoding analysis of oral microbiome during pregnancy

Pregnancy is a dynamic physiological process involving significant hormonal, immune, and metabolic changes to support fetal growth and development. This study investigates the changes in salivary microbiome and biochemical markers from the second to the third trimester of pregnancy. Saliva samples were collected from 45 pregnant women enrolled in the Qatar Birth Cohort study at two time points (second and third trimesters). DNA was extracted and subjected to 16S rRNA gene sequencing using Oxford Nanopore Technology. Microbial diversity and taxonomic analyses were performed, along with correlation analyses between microbial abundance and clinical parameters. Biochemically, significant increases in BMI, pulse rate, HbA1c, LDL, total cholesterol, and triglycerides were observed in the third trimester compared to the second. Microbial diversity analysis revealed significant changes in microbial richness and composition. Taxonomy analysis showed a significant 3-fold increase in Bacteroidota. Also, a significant decline in Selenomonas and a significant increase in Veillonella, specifically Veillonella dispar and Veillonella atypica, as well as an increase in Granulicatella were observed in the third trimester, along with a significant decrease in Streptococcus sanguinis. Correlation analysis during the second trimester revealed positive associations between BMI, cholesterol, LDL, and Selenomonas, and negative correlations with Streptococcus and Gemella. In the third trimester, BMI was negatively correlated with Campylobacter, glucose levels were negatively correlated with Neisseria, and triglyceride levels were negatively correlated with Prevotella. These findings highlight significant biochemical and microbial shifts during pregnancy, underscoring the importance of monitoring oral health and metabolic changes in pregnant women.

Association between Salivary Hormones, Dental Caries, and Cariogenic Microorganisms during Pregnancy

Objective: This study aimed to identify the salivary levels of six hormones (progesterone, estradiol, testosterone, cortisol, thyroxine T3, and triiodothyronine T4) in pregnant women, and to assess the association between salivary hormones, dental caries, and cariogenic microorganisms. Methods: This cross-sectional study included 181 low-income US pregnant women who were in their third trimester. Demographic details, oral hygiene practices, and medical backgrounds were obtained via questionnaires and medical records. Calibrated dentists obtained data on plaque index and caries status through comprehensive oral examinations. Unstimulated saliva was collected 2 h before eating and brushing. Salivary hormones were measured with a multiplex assay. Oral Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) were quantified via colony-forming unit (CFU) counts. A latent model was used to generate clusters of pregnant women based on salivary hormone levels, followed by post-clustering analysis. Factors associated with salivary cariogenic microorganisms were further evaluated via multiple regression analyses. Results: Estradiol, progesterone, testosterone, cortisol, T3, and T4 in saliva were detectable at rates of 92%, 97%, 77%, 99%, 71%, and 50%, respectively. Three distinct participant clusters (high, intermediate, and low) were identified based on salivary hormone levels. Intermediate-level and high-level clusters had increased numbers of decayed teeth, decayed surfaces, ICDAS scores, and salivary S. mutans and C. albicans, compared to the low-level cluster (p < 0.05). Covariate analysis demonstrated that the high-level cluster was positively associated with salivary carriage of S. mutans (CFU/mL) (p < 0.05). Participants with higher levels of progesterone, estradiol, testosterone, and cortisol were associated with a high carriage status of S. mutans in saliva (>105 CFU/mL) (p < 0.05). Conclusions: This study demonstrated the feasibility of detecting salivary hormones during pregnancy and revealed the positive association between salivary steroid hormones and cariogenic pathogens.

The Oral Microbiome Throughout Pregnancy: A Scoping Review

INTRODUCTION

Oral health is associated with systemic health, including adverse pregnancy outcomes. Understanding the oral microbiome during pregnancy may lead to targeted interventions for prevention of adverse outcomes. The purpose of this review is to examine the literature on the oral microbiome throughout pregnancy.

METHODS

We conducted a literature search with four electronic databases for original research conducted between 2012 and 2022 that examined the oral microbiome longitudinally using 16s rRNA sequencing during pregnancy.

RESULTS

We identified six studies that examined the oral microbiome longitudinally throughout pregnancy, though comparisons of oral niches, oral microbiome measures, and findings between studies were not consistent. Three studies identified alterations in alpha diversity throughout pregnancy and two studies identified increased pathogenic bacteria during pregnancy. Three studies reported no changes in the oral microbiome throughout pregnancy, and one study identified differences in the composition of the microbiome based on socioeconomic status and antibiotic exposure. Two studies examined adverse pregnancy outcomes in association with the oral microbiome, one reporting no associations and one reported difference in community gene composition in those diagnosed with preeclampsia.

CLINICAL IMPLICATIONS

There is limited research on the composition of the oral microbiome throughout pregnancy. There may be alterations in the oral microbiome during pregnancy such as increased relative abundance of pathogenic bacteria. Socioeconomic status, antibiotic use, and education may contribute to differences in the microbiome composition over time. Clinicians should evaluate oral health and educate on the importance of oral health care during the prenatal and perinatal time period.

Culturing the Human Oral Microbiota, Updating Methodologies and Cultivation Techniques

Recent years have been marked by a paradigm shift in the study of the human microbiota, with a re-emergence of culture-dependent approaches. Numerous studies have been devoted to the human microbiota, while studies on the oral microbiota still remain limited. Indeed, various techniques described in the literature may enable an exhaustive study of the microbial composition of a complex ecosystem. In this article, we report different methodologies and culture media described in the literature that can be applied to study the oral microbiota by culture. We report on specific methodologies for targeted culture and specific culture techniques and selection methodologies for cultivating members of the three kingdoms of life commonly found in the human oral cavity, namely, eukaryota, bacteria and archaea. This bibliographic review aims to bring together the various techniques described in the literature, enabling a comprehensive study of the oral microbiota in order to demonstrate its involvement in oral health and diseases.

Effects of an Ozonated Water Irrigator on the Plaque Index and Bleeding Index of Pregnant Women

Pregnancy causes physiological changes in the woman’s body, which can also affect oral health. Therefore, pregnant women may manifest gingival inflammation that is favored by their hormonal increase. This clinical trial (ClinicalTrials.gov Identifier: NCT04140643) evaluated the variation in the plaque index (PI) or bleeding index (BOP) in pregnant women after daily use of an ozonated water irrigator and proper home oral hygiene, compared to a control group who only performed home oral hygiene. The inclusion criteria were the gestation period from the 14th week to the 30th week, a diagnosis of gingivitis, and a minimum number of teeth equal to 20. The PI and BOP index were evaluated at T0, fifteen days after T0 (T1), and two months after T1 (T2). The PI values systematically decreased over time (F (1.19) = 41.82) in both groups, with a systematic difference in PI values between the two groups (F (1.19) = 6.28, p = 0.021). A statistically significant difference was assessed in the BOP index at T2 between the two groups, with the control group suffering a higher BOP index. The results show that the patients in the study group showed a decrease in the BOP index over the three time points, in contrast to the control group, due to the beneficial properties of ozonated water.