Open Access
Peer-reviewed
Research Article
Oral microbiome test as an alternative diagnostic tool for gastric alterations: A prospective, bicentric cross-sectional study
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The human microbiome plays a pivotal role in influencing various physiological processes and maintaining overall well-being, including the gastric system. Current diagnostic tests for gastric diseases often involve invasive procedures, sampling limitations, and medication effects, leading to potential diagnostic errors and discomfort to patients. Considering the connection between oral and gastric microbiomes, this cross-sectional study aimed to assess the diagnostic potential of the oral bacterial profile in patients undergoing upper digestive endoscopy. Oral samples from 266 participants across two Brazilian sites (Belterra and Sao Paulo) were sequenced and subjected to bioinformatic analysis to identify microbiome composition across endoscopy outcome groups, exploring alpha and beta-diversity, richness, and differential abundance and prevalence. _Prevotella_, _Haemophilus_, _Fusobacterium_, _Neisseria_, and _Streptococcus_ were the most abundant genera observed. No significant associations were found between alpha diversity profiles and endoscopy outcomes; beta diversity analyses similarly showed no correlations. Overall, the study did not establish the oral microbiome as a reliable marker for gastric health, underscoring the necessity for broader studies in the development of non-invasive diagnostic tests.
Citation:Martins FP, Andrade-Silva J, Teixeira BL, Ferrari A, Christoff AP, Cruz GNF, et al. (2024) Oral microbiome test as an alternative diagnostic tool for gastric alterations: A prospective, bicentric cross-sectional study. PLoS ONE 19(12): e0314660.
Editor:Baochuan Lin, Defense Threat Reduction Agency, UNITED STATES OF AMERICA
Received:January 12, 2024; Accepted:November 13, 2024; Published: December 2, 2024
Copyright: © 2024 Martins et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability:All sequence data have been deposited in the NCBI BioProject under the accession number PRJNA604445. All data and code are available from GitHub database.
Funding:The funders BiomeHub and Albert Einstein Israelite Hospital (HIAE) provided support in form of salaries for the authors and were responsible for the project experimental design approval. HIAE have an additional role in defining sample collection points, but the analysis, the decision to publish and the manuscript preparation was independently performed by the researchers. The specific roles of each author are included in the ‘author contributions’ section.
Competing interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Bianca Luise Teixeira, Ana Paula Christoff, Giuliano Netto Flores and Luiz Felipe Valter de Oliveira are currently fulltime employees of BiomehHub Biotechnologies. All other authors declare no conflict of interest. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
Various regions of the body harbor distinct microbial populations, each contributing to specific functions and interactions. The balance of bacterial composition, metabolic activities, and distribution within the gut plays a crucial role in determining overall health and susceptibility to illness. The relationship between oral and gastric microbiota is intricate, dynamic, and interconnected, with a complex interplay between these microbial communities that can influence oral and gastric health.
The global prevalence of upper digestive system disease cases was 780.59 million in 2019, representing about 10% of the world’s population; changes in the structure and function of the stomach can be caused by the presence of microorganisms or the imbalance of the local microbiota. _Helicobacter pylori_, a gram-negative pathogen, is the predominant microorganism associated with gastric infections, with approximately half of the world’s population being colonized. _H_. _pylori_ significantly increases the risk of chronic gastritis, ulcers, and various forms of cancer, including adenocarcinoma, as established by World Health Organization’s International Agency for Research on Cancer (IARC). Other microbes than _H_. _pylori_ also play a role in the development of gastric cancer, such as _Peptostreptococcus_, _Desulfovibrio_, and _Fusobacterium_. Changes in the gastric microbial structure could be seen in different precancerous stages, from superficial gastritis to atrophic gastritis, and gastric intraepithelial neoplasia to gastric cancer. In that sense, the gastric microbiota might play different roles in carcinogenesis.
Multiple invasive and non-invasive diagnostic tests are available to detect pathogenic microorganisms that can potentially influence human health. The selection of a suitable test depends on factors such as test availability, the patient’s clinical condition, and the diagnostic accuracy observed in different clinical scenarios. Invasive procedures, like upper digestive endoscopy, are commonly employed to diagnose _H_. _pylori_ infection. Additional invasive tests can be performed on the mucosal tissue by obtaining a gastric biopsy, including urease testing, histology, culture, and molecular methods. However, since the distribution of infection within the gastric mucosa is not uniform, there is a possibility of diagnostic errors due to sampling limitations. Furthermore, certain medications like proton pump inhibitors and antibiotics can decrease the sensitivity of those tests.
Considering the vital link between the oral and gastric microbiome, previous studies have shown that changes in the richness, evenness, and/or number of bacterial species inside the oral cavity could be a diagnostic biomarker for chronic gastritis and gastric cancer.
Therefore, developing a non-invasive method that evaluates the oral microbiome from a buccal sample seems important for gastric disease screening and diagnosis. In this study, we aimed to evaluate the oral bacterial profile in patients referred for upper digestive endoscopy to assess its diagnostic potential related to gastric alterations.
The study was approved by the Research Ethics Committee of Hospital Israelita Albert Einstein (approval numbers 2.392.780 and 4.333.608) and was conducted according to the principles expressed in the Declaration of Helsinki. All subjects provided written informed consent.
A prospective cross-sectional survey was carried out at two centers in Brazil, located in Belterra (Cohort 1) and São Paulo (Hospital Israelita Albert Einstein—Cohort 2) from November to December 2017, and from March to September 2021, respectively. The primary outcome was a composite of gastric alterations as detected in endoscopy, including erosive esophagitis and/or gastroduodenal peptic disease. The study is reported according to both the STROBE statement for cross-sectional investigations and the STORMS statement for human microbiome studies.
Participants with an indication of upper digestive endoscopy to detect gastric alterations were recruited consecutively based on predefined inclusion and exclusion criteria. The study inclusion criteria were age > 18 years old, referral to upper digestive endoscopy for detection of gastric alterations, even when the participants were using proton pump inhibitors and/or antibiotics. Participants who had eaten or brushed their teeth in the 4 hours before the sample collection were excluded. Also, we excluded participants with esophagus, stomach, or duodenum surgery history since this factor can change the endoscopic findings regardless of the presence of microorganisms. Those who did not sign the informed consent form were not included.
After consent, all eligible participants answered a specific questionnaire used for sociodemographic, lifestyle, and clinical data collection. Sociodemographic variables included age, sex, and education; lifestyle habits data included smoking and alcohol use. Clinical variables consisted of symptoms, use of proton pump inhibitors, use of antibiotics in the last 30 days, and the upper digestive endoscopy results.
For oral microbiome analysis, sampling was performed using sterile nylon flocked swabs (Copan Inc., Italy or Puritan, USA) and stored in a stabilizing solution (BiomeHub, Brazil) for transport at room temperature. Samples were collected with a swab from the posterior region of the oral cavity (which includes teeth (molars and premolars), plaque regions, oral mucosa, and dorsal tongue). This approach covers multiple oral sites and comprehensively represents the oral microbiota, reducing potential bias from specific areas. The swabs were transported to the laboratory facilities at room temperature and processed within a maximum of 30 days after sample collection. Bacterial DNA from the samples was obtained using the DNeasy Qiaamp DNA Blood Mini Kit (QIAGEN) according to the manufacturer’s instructions.
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