Characterization of oral microbiota and acetaldehyde production

Metagenomic shotgun sequencing reveals the enrichment of Salmonella and Mycobacterium in larynx due to prolonged ethanol exposure

The exposure of ethanol increases the risk of head and neck inflammation and tumor progression. However, limited studies have investigated the composition and functionality of laryngeal microbiota under ethanol exposure. We established an ethanol-exposed mouse model to investigate the changes in composition and function of laryngeal microbiota using Metagenomic shotgun sequencing. In the middle and late stages of the experiment, the laryngeal microbiota of mice exposed to ethanol exhibited obvious distinguished from that of the control group on principal-coordinate analysis (PCoA) plots. Among the highly abundant species, Salmonella enterica and Mycobacterium marinum were likely to be most impacted. Our findings indicated that the exposure to ethanol significantly increased their abundance in larynxes in mice of the same age, which has been confirmed through FISH experiments. Among the species-related functions and genes, metabolism is most severely affected by ethanol. The difference was most obvious in the second month of the experiment, which may be alleviated later because the animal established tolerance. Notable enrichments concerning energy, amino acid, and carbohydrate metabolic pathways occurred during the second month under ethanol exposure. Finally, based on the correlation between species and functional variations, a network was established to investigate relationships among microbiota, functional pathways, and related genes affected by ethanol. Our data first demonstrated the continuous changes of abundance, function and their interrelationship of laryngeal microbiota under ethanol exposure by Metagenomic shotgun sequencing.

Importance

Ethanol may participate in the inflammation and tumor progression by affecting the composition of the laryngeal microbiota. Here, we applied the metagenomic shotgun sequencing instead of 16 S rRNA sequencing method to identify the laryngeal microbiota under ethanol exposure. Salmonella enterica and Mycobacterium marinum are two dominant species that may play a role in the reconstruction of the laryngeal microenvironment, as their local abundance increases following exposure to ethanol. The metabolic function is most evidently impacted, and several potential metabolic pathways could be associated with alterations in microbiota composition. These findings could help us better understand the impact of prolonged ethanol exposure on the microbial composition and functionality in the larynx.

Oral microbial dysbiosis in patients with oral cavity cancers

OBJECTIVES

The pathogenesis of oral cavity cancers is complex. We tested the hypothesis that oral microbiota dysbiosis is associated with oral cavity cancer.

MATERIALS AND METHODS

Patients with primary oral cavity cancer who met the inclusion and exclusion criteria were included in the study. Matching healthy individuals were recruited as controls. Data on socio-demographic and behavioral factors, self-reported periodontal measures and habits, and current dental status were collected using a structured questionnaire and periodontal chartings. In addition to self-reported oral health measures, each participant received a standard and detailed clinical examination. DNA was extracted from saliva samples from patients and healthy controls. Next-generation sequencing was performed by targeting V3-V4 gene regions of the 16 S rRNA with subsequent bioinformatic analyses.

RESULTS

Patients with oral cavity cancers had a lower quality of oral health than healthy controls. Proteobacteria, Aggregatibacter, Haemophilus, and Neisseria decreased, while Firmicutes, Bacteroidetes, Actinobacteria, Lactobacillus, Gemella, and Fusobacteria increased in oral cancer patients. At the species level, C. durum, L. umeaens, N. subflava, A. massiliensis, and V. dispar were significantly lower, while G. haemolysans was significantly increased (p < 0.05). Major periodontopathogens associated with periodontal disease (P. gingivalis and F.nucleatum) increased 6.5- and 2.8-fold, respectively.

CONCLUSION

These data suggested that patients with oral cancer had worse oral health conditions and a distinct oral microbiome composition that is affected by personal daily habits and may be associated with the pathogenicity of the disease and interspecies interactions.

CLINICAL RELEVANCE

This paper demonstrates the link between oral bacteria and oral cancers, identifying mechanistic interactions between species of oral microbiome.

Salivary Metabolites Produced by Oral Microbes in Oral Diseases and Oral Squamous Cell Carcinoma: A Review

In recent years, salivary metabolome studies have provided new biological information and salivary biomarkers to diagnose different diseases at early stages. The saliva in the oral cavity is influenced by many factors that are reflected in the salivary metabolite profile. Oral microbes can alter the salivary metabolite profile and may express oral inflammation or oral diseases. The released microbial metabolites in the saliva represent the altered biochemical pathways in the oral cavity. This review highlights the oral microbial profile and microbial metabolites released in saliva and its use as a diagnostic biofluid for different oral diseases. The importance of salivary metabolites produced by oral microbes as risk factors for oral diseases and their possible relationship in oral carcinogenesis is discussed.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune and clinical markers of microbiomes from four body sites in 86 participants over six years. We found that microbiome stability and individuality are body-site-specific and heavily influenced by the host. The stool and oral microbiome were more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. Also, we identified individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlated across body sites, suggesting systemic coordination influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals showed altered microbial stability and associations between microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Study Highlights

The stability of the human microbiome varies among individuals and body sites.Highly individualized microbial genera are more stable over time.At each of the four body sites, systematic interactions between the environment, the host and bacteria can be detected.Individuals with insulin resistance have lower microbiome stability, a more diversified skin microbiome, and significantly altered host-microbiome interactions.

Alcohol consumption and oral microbiome composition in a sample of healthy young adults

The oral microbiomes of 24 healthy adults (50% female; mean age = 24.3) were examined using 16 s ribosomal RNA sequencing and compared between light and heavy drinkers. Beta diversity was related at the trend level to drinking group, and light drinkers had significantly higher abundances of key oral taxa such as Lactobacillales. These preliminary results may offer insight into early effects of heavy drinking on the composition of the oral microbiome.

The Influence of the Oral Microbiome on Oral Cancer: A Literature Review and a New Approach

In our recent article (Smędra et al.: Oral form of auto-brewery syndrome. J Forensic Leg Med. 2022; 87: 102333), we showed that alcohol production can occur in the oral cavity (oral auto-brewery syndrome) due to a disruption in the microbiota (dysbiosis). An intermediate step on the path leading to the formation of alcohol is acetaldehyde. Typically, acetic aldehyde is transformed into acetate particles inside the human body via acetaldehyde dehydrogenase. Unfortunately, acetaldehyde dehydrogenase activity is low in the oral cavity, and acetaldehyde remains there for a long time. Since acetaldehyde is a recognised risk factor for squamous cell carcinoma arising from the oral cavity, we decided to analyse the relationship linking the oral microbiome, alcohol, and oral cancer using the narrative review method, based on browsing articles in the PubMed database. In conclusion, enough evidence supports the speculation that oral alcohol metabolism must be assessed as an independent carcinogenic risk. We also hypothesise that dysbiosis and the production of acetaldehyde from non-alcoholic food and drinks should be treated as a new factor for the development of cancer.

Differences in the subgingival microbial composition associated with alcohol intake: A systematic review

Objectives

This study aimed to conduct a systematic evaluation of the literature on whether individuals exposed to alcohol intake present differences in the subgingival microbial composition compared to those unexposed.

Methods

Five databases (MEDLINE, EMBASE, LILACS, SCOPUS and Web of Science) and one source of grey literature (Google Scholar) were searched by two independent reviewers up to December 2022 according to pre-specified eligibility criteria. No restrictions were imposed regarding the date and language of publication and the periodontal status of the participants. The Newcastle-Ottawa Scale was used for methodological quality appraisal and a narrative synthesis was performed.

Results

Eight cross-sectional studies and one cross-sectional analysis nested in a cohort were considered for qualitative analysis, including data of 4636 individuals. Overall, the studies exhibited considerable heterogeneity in terms of characteristics of the participants and microbiological methods. Four studies have high methodological quality. Exposed individuals have higher overall quantity of periodontal pathogens in shallow and moderate to deep pockets. Findings on richness, relative abundance, alpha- and beta-diversity were limited and inconclusive.

Conclusion

The subgingival microbiota of individuals exposed to alcohol intake has higher overall quantity of red (i.e., P. gingivalis) and orange-complex (i.e., F. nucleatum) bacteria when compared to those unexposed.

The interplay between oral microbes and immune responses

Oral microbes play a critical role in maintaining oral homeostasis. Microbial dysbiosis promotes disease pathogenesis through several mechanisms. Recent studies have revealed that microbial imbalance and sustained inflammation are involved in disease progression. The adverse interaction triggered by a host immune response to microorganisms can lead to oral and systemic diseases. Here, we reviewed how oral microbes communicate with hosts during the development of local and distant inflammation. Elucidation of these processes may reveal future directions in this field and the potential targets of novel biological therapies for oral and systemic diseases.

Yogurt product intake and reduction of tooth loss risk in a Japanese community

Aim

To evaluate the longitudinal association between yogurt product intake and oral health in a population‐based study.

Materials and Methods

This study included 1967 Japanese residents aged 40–79 years who underwent dental examinations in 2012. Among them, 1469 participants were followed up in 2017 for the incidence of tooth loss, which was defined as two or more teeth lost over 5 years. The intake of yogurt products, defined as yogurt and lactic acid beverages, was estimated using a semi‐quantitative food frequency questionnaire. The composition of the salivary microbiota was evaluated.

Results

The Poisson regression model showed that a higher intake of yogurt products was negatively associated with the incidence of tooth loss (p for trend = .020), adjusted for potential confounding factors. Mediation analysis confirmed that periodontal condition partly mediated the effect of yogurt product intake on tooth loss, while dental caries experience did not. Additionally, we confirmed the association of a high intake of yogurt products with a low percentage of the salivary microbiota pattern, which was associated with poor oral health.

Conclusion

These findings suggest that the intake of yogurt products is associated with a lower risk of tooth loss resulting from periodontal disease, probably via modulation of the oral microbiome composition.

A Fresh Look at Mouthwashes-What Is Inside and What Is It For?

Mouthwashes are a very popular additional oral hygiene element and there are plenty of individual products, whose compositions are in a state of flux. The aim of our study was to investigate the compositions of mouthwashes and their functions, as well as to discuss their effectiveness in preventing and curing oral diseases and side effects. We searched for mouthwashes available on the market in Poland. We identified 241 individual mouthwash products. The extraction of compositions was performed and functions of the ingredients were assessed. Then, analysis was performed. The evaluation revealed that there are plenty of ingredients, but a typical mouthwash is a water–glycerine mixture and consists of additional sweetener, surfactant, preservative, and some colourant and flavouring agent, as well as usually having two oral health substances, anticaries sodium fluoride and antimicrobial essential oils. The effectiveness or side effects of several substances of mouthwashes were thoroughly discussed. We recommend not multiplying individual mouthwash products and their ingredients beyond medical or pharmaceutical necessity, especially without scientific proof.

Alcohol and Head and Neck Cancer: Updates on the Role of Oxidative Stress, Genetic, Epigenetics, Oral Microbiota, Antioxidants, and Alkylating Agents

Head and neck cancer (HNC) concerns more than 890,000 patients worldwide annually and is associated with the advanced stage at presentation and heavy outcomes. Alcohol drinking, together with tobacco smoking, and human papillomavirus infection are the main recognized risk factors. The tumorigenesis of HNC represents an intricate sequential process that implicates a gradual acquisition of genetic and epigenetics alterations targeting crucial pathways regulating cell growth, motility, and stromal interactions. Tumor microenvironment and growth factors also play a major role in HNC. Alcohol toxicity is caused both directly by ethanol and indirectly by its metabolic products, with the involvement of the oral microbiota and oxidative stress; alcohol might enhance the exposure of epithelial cells to carcinogens, causing epigenetic modifications, DNA damage, and inaccurate DNA repair with the formation of DNA adducts. Long-term markers of alcohol consumption, especially those detected in the hair, may provide crucial information on the real alcohol drinking of HNC patients. Strategies for prevention could include food supplements as polyphenols, and alkylating drugs as therapy that play a key role in HNC management. Indeed, polyphenols throughout their antioxidant and anti-inflammatory actions may counteract or limit the toxic effect of alcohol whereas alkylating agents inhibiting cancer cells’ growth could reduce the carcinogenic damage induced by alcohol. Despite the established association between alcohol and HNC, a concerning pattern of alcohol consumption in survivors of HNC has been shown. It is of primary importance to increase the awareness of cancer risks associated with alcohol consumption, both in oncologic patients and the general population, to provide advice for reducing HNC prevalence and complications.

The Role of Periodontopathogens and Oral Microbiome in the Progression of Oral Cancer. A Review

Chronic periodontal disease and oral bacteria dysbiosis can lead to the accumulation of genetic mutations that eventually stimulate Oral Squamous Cell Cancer (OSCC). The annual incidence of OSCC is increasing significantly, and almost half of the cases are diagnosed in an advanced stage. Worldwide there are more than 380,000 new cases diagnosed every year, and a topic of extensive research in the last few years is the alteration of oral bacteria, their compositional changes and microbiome. This review aims to establish the relationship between bacterial dysbiosis and OSCC. Several bacteria implicated in periodontal disease, including Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and some Streptococcus species, promote angiogenesis, cell proliferation, and alteration in the host defense process; these same bacteria have been present in different stages of OSCC. Our review showed that genes involved in bacterial chemotaxis, the lipopolysaccharide (LPS) of the cell wall membrane of gram negatives bacteria, were significantly increased in patients with OSCC. Additionally, some bacterial diversity, particularly with Firmicutes, and Actinobacteria species, has been identified in pre-cancerous stage samples. This review suggests the importance of an early diagnosis and more comprehensive periodontal therapy for patients by the dental care professional.

Oral microbiota and vitamin D impact on oropharyngeal squamous cell carcinogenesis: a narrative literature review

An emerging body of research is revealing the microbiota pivotal involvement in determining the health or disease state of several human niches, and that of vitamin D also in extra-skeletal regions. Nevertheless, much of the oral microbiota and vitamin D reciprocal impact in oropharyngeal squamous cell carcinogenesis (OPSCC) is still mostly unknown. On this premise, starting from an in-depth scientific bibliographic analysis, this narrative literature review aims to show a detailed view of the state of the art on their contribution in the pathogenesis of this cancer type. Significant differences in the oral microbiota species quantity and quality have been detected in OPSCC-affected patients; in particular, mainly high-risk human papillomaviruses (HR-HPVs), Fusobacterium nucleatum, Porphyromonas gingivalis, Pseudomonas aeruginosa, and Candida spp. seem to be highly represented. Vitamin D prevents and fights infections promoted by the above identified pathogens, thus confirming its homeostatic function on the microbiota balance. However, its antimicrobial and antitumoral actions, well-described for the gut, have not been fully documented for the oropharynx yet. Deeper investigations of the mechanisms that link vitamin D levels, oral microbial diversity and inflammatory processes will lead to a better definition of OPSCC risk factors for the optimization of specific prevention and treatment strategies.

Dysbiosis of Oral Microbiota Associated with Palmoplantar Pustulosis

BACKGROUND

Dysbiosis of oral microbiota is implicated not only in oral inflammatory lesions, but also in a variety of extraoral diseases. The etiology of palmoplantar pustulosis (PPP) remains unclear; however, it has been suggested that chronic inflammation caused by periodontopathic bacterial infection may play a role.

OBJECTIVES/METHODS

To determine whether patients with PPP have altered diversity and composition of oral microbiota, we conducted the 16S rDNA analysis using saliva samples collected from 21 outpatients with PPP and 10 healthy individuals.

RESULTS

We found that the proportion of bacteria in the phylum Proteobacteria was significantly lower in PPP patients (p = 0.025). At the genus level, patients with PPP had a significantly lower abundance of Neisseria (p = 0.014), which best accounted for the observed decrease in Proteobacteria. We also identified multiple minor genera and species that were represented at a significantly higher level in the PPP group, several of which have been associated with periodontal diseases.

CONCLUSION

Our results suggest a possible link between PPP and dysbiosis of oral microbiota, particularly the lower abundance of Neisseria, the most predominant genus of Proteobacteria in healthy oral microbiota. Probiotics that improves oral dysbiosis may be beneficial for patients with PPP as an adjunctive therapy.

The interplay of the oral microbiome and alcohol consumption in oral squamous cell carcinomas

Oral cancer (OC) is among the top twenty occurring cancers in the world, with a mortality rate of 50%. A shift to a functionally inflammatory or a 'disease state' oral microbiome composition has been observed amongst patients with premalignant disorders and OC, with evidence suggesting alcohol could be exacerbating the inflammatory influence of the oral microorganisms. Alcohol dehydrogenase (ADH, EC 1.1.1.1) converts alcohol into a known carcinogenic metabolite, acetaldehyde and while ADH levels in oral mucosa are low, several oral commensal species possess ADH and could produce genotoxic levels of acetaldehyde. With a direct association between oral microbiome status, alcohol and poor oral health status combining to induce chronic inflammation with increased acetaldehyde levels - this leads to a tumour promoting environment. This new disease state increases the production of reactive oxygen species (ROS), while impairing anti-oxidant systems thus activating the redox signalling required for the promotion and survival of tumours. This review aims to highlight the evidence linking these processes in the progression of oral cancer.

Local Acetaldehyde: Its Key Role in Alcohol-Related Oropharyngeal Cancer

Background

Alcohol consumption and ethanol in alcoholic beverages are group 1 carcinogens, that is, carcinogenic to humans. However, ethanol itself is neither genotoxic nor mutagenic. Based on unique gene-epidemiologic and gene-biochemical evidence, the first metabolite of ethanol oxidation - acetaldehyde (ACH) - acts as a local carcinogen in the oropharynx. This review is focused on those facts, which highlight the importance of the oropharynx and local ACH in the pathogenesis of alcohol-related oropharyngeal cancer.

Summary

The strongest evidence for the local carcinogenicity of ACH in man provides a point mutation in the aldehyde dehydrogenase 2 (ALDH2) gene, which has randomized millions of alcohol consumers to markedly increased ACH exposure via saliva. This novel human cancer model is associated with manifold risk for oropharyngeal cancer and most importantly it is free from confounding factors markedly hampering epidemiological studies on alcohol-related cancer. The oropharynx is an ideal target organ for the cancer risk assessment of ACH. There is substantial epidemiological data on alcohol-related oropharyngeal cancer risk and also on salivary ACH concentrations among major risk groups for oropharyngeal cancer. Normal human saliva does not contain measurable levels of ACH. However, alcohol ingestion results within seconds in a concentration-dependent accumulation of ACH in saliva, which continues for up to 10-15 min after each sip of alcoholic beverage. This instant ACH exposure phase is followed by a long-term phase derived from ethanol diffused back to saliva from blood circulation. Microbes representing normal oral flora play a major role in local ACH formation from ethanol. In ALDH2-deficient subjects excess ACH during the long-term ACH exposure phase is most probably derived from salivary glands.

Key Message

ALDH2 gene mutation proves the causal relationship between local ACH exposure via saliva and oropharyngeal cancer and provides new means for the quantitative assessment of local ACH exposure in relation to oropharyngeal cancer risk. Instant ACH formation from ethanol represents approximately 70-100% of total local ACH exposure. Ethanol present in "non-alcoholic" beverages and food forms an epidemiological bias in studies on alcohol-related upper digestive tract cancer.

Responses

One should quit smoking, adopt sensible drinking habits, and maintain good oral hygiene. Genetic risk groups could be screened and educated. Consumption of beverages and foodstuffs containing low ethanol levels as well as alcoholic beverages containing high ACH levels should be minimized. To that aim, labelling of alcohol and ACH concentrations of all beverages and foodstuffs should be mandatory.

sMETASeq: Combined Profiling of Microbiota and Host Small RNAs

Understanding microbial communities' roles in human health and disease requires methods that accurately characterize the microbial composition and their activity and effects within human biological samples. We present sMETASeq (small RNA Metagenomics by Sequencing), a novel method that uses sequencing of small RNAs to jointly measure host small RNA expression and create metagenomic profiles and detect small bacterial RNAs. We evaluated the performance of sMETASeq on a mock bacterial community and demonstrated its use on different human samples, including colon cancer, oral leukoplakia, cervix cancer, and a panel of human biofluids. In all datasets, the detected microbes reflected the biology of the different sample types.

Acetaldehyde production by Rothia mucilaginosa isolates from patients with oral leukoplakia

Rothia mucilaginosa has been found at high abundance on oral leukoplakia (OLK). The ability of clinical isolates to produce acetaldehyde (ACH) from ethanol has not been investigated. The objective of the current study was to determine the capacity of R. mucilaginosa isolates recovered from OLK to generate ACH. Analysis of R. mucilaginosa genomes (n = 70) shows that this species does not normally encode acetaldehyde dehydrogenase (ALDH) required for detoxification of ACH. The predicted OLK metagenome also exhibited reduced ALDH coding capacity. We analysed ACH production in 8 isolates of R. mucilaginosa and showed that this species is capable of generating ACH in the presence of ethanol. The levels of ACH produced (mean = 53 µM) were comparable to those produced by Neisseria mucosa and Candida albicans in parallel assays. These levels were demonstrated to induce oxidative stress in cultured oral keratinocytes. This study shows that R. mucilaginosa can generate ACH from ethanol in vitro at levels which can induce oxidative stress. This organism likely contributes to oral ACH levels following alcohol consumption and the significance of the increased abundance of R. mucilaginosa in patients with potentially malignant disorders requires further investigation.

Oropharyngeal Squamous Cell Carcinoma: Human Papilloma Virus Coinfection with Streptococcus anginosus

Abstract Introduction: Human papilloma virus (HPV) and oral bacteria capable of acetaldehyde production from ethanol, such as Streptococcus anginosus, Prevotella melaninogenica, and Fusobacterium naviforme are among oropharyngeal squamous cell carcinoma (OSCC) infectious risk factors. Objective: Determine associations with HPV and S. anginosus, P. melaninogenica, and F. naviforme in patients with and without OSCC. Methods: Presence of HPV and HPV-16 was determined in 26 patients with OSCC and 26 without OSCC by conventional PCR and simultaneous presence of S. anginosus, P. melaninogenica, and F. naviforme quantification through q-PCR. Statistical analysis was carried out using Pearson’s X² and Student’s-t test. Results: Patients with OSCC had HPV and HPV-16 frequencies of 84% and 61.5%, respectively, in contrast for patients without OSCC frequencies were 34.6 and 30.7%. P. melaninogenica, and F. naviforme microorganisms were not present in any participant in this study. S. anginosus frequency in patients with OSC was 38.4% and in patients without OSCC was 30.7%. Patients with OSCC had S. anginosus + HPV co-infection at a 38.4% frequency and S. anginosus + HPV-16 at a 23.1% frequency. For individuals without OSCC S. anginosus + HPV co-infection was 3.8% and S. anginosus + HPV-16 3.8%. A greater frequency of S. anginosus + HPV co-infection and S. anginosus + HPV-16 was observed in patients with OSCC in comparison with individuals without OSCC, suggesting the importance of detecting HPV/HPV-16 and S. anginosus simultaneously in individuals at risk of developing OSCC

Contributing Roles of CYP2E1 and Other Cytochrome P450 Isoforms in Alcohol-Related Tissue Injury and Carcinogenesis

The purpose of this review is to briefly summarize the roles of alcohol (ethanol) and related compounds in promoting cancer and inflammatory injury in many tissues. Long-term chronic heavy alcohol exposure is known to increase the chances of inflammation, oxidative DNA damage, and cancer development in many organs. The rates of alcohol-mediated organ damage and cancer risks are significantly elevated in the presence of co-morbidity factors such as poor nutrition, unhealthy diets, smoking, infection with bacteria or viruses, and exposure to pro-carcinogens. Chronic ingestion of alcohol and its metabolite acetaldehyde may initiate and/or promote the development of cancer in the liver, oral cavity, esophagus, stomach, gastrointestinal tract, pancreas, prostate, and female breast. In this chapter, we summarize the important roles of ethanol/acetaldehyde in promoting inflammatory injury and carcinogenesis in several tissues. We also review the updated roles of the ethanol-inducible cytochrome P450-2E1 (CYP2E1) and other cytochrome P450 isozymes in the metabolism of various potentially toxic substrates, and consequent toxicities, including carcinogenesis in different tissues. We also briefly describe the potential implications of endogenous ethanol produced by gut bacteria, as frequently observed in the experimental models and patients of nonalcoholic fatty liver disease, in promoting DNA mutation and cancer development in the liver and other tissues, including the gastrointestinal tract.

Significance of oral health in adult patients with congenital heart disease

Due to improved diagnosis and treatment life expectancy of patients with congenital heart disease is steadily increasing resulting in a growing portion of adult patients. When entering, adulthood patients commonly show a shift in their specific needs for medical care. Since the treatment is mostly not curative many patients have life-long cardiovascular anomalies, among others, entailing high risk for the development of infective endocarditis. Several oral diseases, i.e., caries, apical periodontitis and periodontitis show a very high overall prevalence. These entities are primarily initiated by bacterial infections. Hence, they cause an inherent risk for bacteremia and subsequently for infective endocarditis in patients with congenital heart disease during professional dental care and various daily activities. Conversely congenital heart disease seems to be inevitably associated with considerable impairment of oral health resulting in a tight interrelation between both entities. Different preventive strategies are available to address the elevated risk for infective endocarditis due to oral diseases in patients with congenital heart disease during professional dental care and routine daily activities. This review delineates the current evidence regarding the issue of oral health in adult patients with congenital heart disease.

Characteristics of the Salivary Microbiota in Patients With Various Digestive Tract Cancers

The salivary microbiota is constantly swallowed and delivered to the digestive tract. These bacteria may be associated with gastrointestinal diseases. This case-control study examined the salivary microbiota in patients with digestive tract cancer (DTC) and evaluated their differential distribution based on the cancer sites. We collected saliva samples from 59 patients with cancer in any part of the digestive tract (tongue/pharynx, esophagus, stomach, and large intestine) and from 118 age- and sex-matched control subjects. There was no significant difference in periodontal status between DTC patients and control subjects (P = 0.72). We examined the bacterial diversity and composition in saliva by 16S ribosomal RNA gene sequencing. Salivary bacterial diversity in DTC patients was significantly higher than that in control subjects [number of operational taxonomic units (OTUs), P = 0.02; Shannon index, P < 0.01; Chao1, P = 0.04]. Eleven differentially abundant OTUs in DTC patients were identified using the linear discriminant analysis effect size (LEfSe) method. Based on the cancer sites, the diversity of salivary bacteria was especially higher in tongue/pharyngeal or esophageal cancer patients than in control subjects. Among the 11 differentially abundant OTUs in DTC patients, an OTU corresponding to Porphyromonas gingivalis was more abundant in the saliva of all groups of DTC patients compared to that in control subjects, and an OTU corresponding to Corynebacterium species was more abundant in all groups other than gastric cancer patients (P < 0.01). In addition, the relative abundances of OTUs corresponding to Fusobacterium nucleatum, Streptococcus parasanguinis II, and Neisseria species were significantly higher in tongue/pharyngeal cancer patients compared to their abundances in control subjects (P < 0.01). The relative abundance of an OTU corresponding to the Neisseria species was also significantly higher in gastric cancer patients and that of an OTU corresponding to Actinomyces odontolyticus was significantly higher in colorectal cancer patients (P < 0.01). These results suggest that the salivary microbiota might be associated with various digestive tract cancers.

Relationship between acetaldehyde concentration in mouth air and characteristics of microbiota of tongue dorsum in Japanese healthy adults: a cross-sectional study

Acetaldehyde, associated with consumption of alcoholic beverages, is known to be a carcinogen and to be related to the tongue dorsum.