Journal of Oral Microbiology最新文献

Background: Nitrite (NO₂ ^-) is produced through enzymatic reduction of dietary nitrate (NO₃ ^-) by oral bacteria: a process contributing to cardiovascular - and possibly oral - health. NO₂ ^- quantitation in biological samples is a complex exercise, and available methods are not well-adapted for chairside use. Therefore, we aimed to develop and evaluate a semi-quantitative chairside test for NO₂ ^- in oral samples. We also evaluated NO₂ ^- generation in several bacterial species in vitro.

Materials and methods: From 12 healthy individuals, tongue, saliva and plaque samples were collected and evaluated chairside across 4 weeks, using the rapid Griess assay (RGA). The RGA was further used to test bacterial species for NO₂ ^- production.

Results: In saliva, plaque and tongue samples, low, variable and high NO₂ ^- levels, respectively, were found. Tongue samples were the most stable over time. High and medium NO₂ ^- production capacities were shown by Actinomyces spp. (including Schaalia odontolytica), Veillonella parvula, and Rothia spp. RGA results were reproducible.

Conclusion: The RGA provided stable and reliable results for chairside NO₂ ^- semi-quantitation, and revealed elevated and stable NO₂ ^- levels on the tongue. In vitro, bacterial NO₂ ^- production was consistent with the available literature, but uncertainty remains regarding Neisseria spp. Our results showed promise for clinical and research applications of the RGA.

Objectives: To investigate the oral microbiome and metabolome longitudinal changes associated with orthodontic treatment-induced gingival enlargement (OT-GE).

Methods: Twenty-six subjects were divided into case and control groups based on the gingival overgrowth index (GOi). The OT-GE group was divided into the no gingival enlargement (OT-GE0, n = 5) and persistent gingival enlargement (OT-GE1, n = 11). The control group included orthodontic treatment periodontal health (OT-GH, n = 5), and no orthodontic treatment periodontal health (NOT-GH, n = 5). Microbial composition and metabolites in saliva were investigated using cross-omics.

Results: Longitudinal analysis linked orthodontic treatment-induced gingival enlargement to distinct oral microbiome and metabolome shifts. The OT-GE group showed significantly higher bleeding on probing (BOP), plaque scores (p < 0.001), probing depth, GOi, and ligature wire differences (p < 0.05) versus controls. Microbial diversity and species richness were elevated in OT-GE (p < 0.05), though no differences emerged between OT-GE0 and OT-GE1) subgroup (p > 0.05). Cross-omics identified specific periodontal pathogens and metabolites linked to gingival enlargement. Disrupted amino acid biosynthesis pathways, particularly citrulline metabolism, correlated with functional gene dysregulation and microbial imbalance. Aberrant citrulline intake appeared to drive dysbiosis, potentially contributing to gingival overgrowth.

Conclusions: OT-GE pathogenesis involves functional gene-regulated metabolite metabolism influencing periodontal pathogens.

Introduction: Coaggregation may reduce the abundance of bacteria in physiological fluids, such as saliva, as aggregated bacteria are cleared more easily than planktonic cells. This study aimed to identify Lactobacillus strains that coaggregate with oral pathogens with the perspective of using this approach to improve oral health.

Material and methods: Coaggregation of 719 postbiotic Lactobacillus strains with target pathogens Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia was quantified by absorbance. Coaggregation efficacy of selected strains with clinical isolates and in the presence of other salivary bacteria was determined by flow cytometry. Brightfield and confocal microscopy were applied to characterize the size and structure of coaggregates. Pangenome analysis was used to identify genomic regions potentially involved in the coaggregation activity.

Results: Two strains, Lacticaseibacillus rhamnosus 1B06 and Lacticaseibacillus paracasei 8A12, coaggregated efficiently with all three target pathogens and clinical isolates of the same species even in the presence of other salivary bacteria. The coaggregation capability of the selected Lactobacillus strains was unique and could not be reproduced with other genetically similar lactic acid bacteria of the same species.

Conclusion: Lactobacillus strains capable of coaggregating oral pathogens were identified as promising candidates for the development of new postbiotic ingredients for oral hygiene products.

Background: Although touted as a safer alternative to cigarette smoking, electronic cigarette usage has been increasingly linked to a myriad of health issues and appears to impact the oral microbiome. Meanwhile, nitrate supplementation has shown promise as a prebiotic that induces positive effects on the oral microbiome.

Methods: In this pilot study, the impact of nitrate supplementation as a countermeasure to e-cigarette usage was explored using in vitro growth and 16S rRNA analysis of microcosms derived from e-cigarette users and nonusers and supplementation with nitrate-rich beetroot juice extract.

Results: The impacts of e-cigarette usage and beetroot supplementation were somewhat limited, with beetroot juice extract supplementation having a significant impact on diversity according to some, but not all, diversity metrics examined. The saliva of the e-cigarette users was depleted in nitrate-reducing Neisseria spp. In terms of differentially abundant individual taxa, the addition of beetroot juice extract to the saliva-derived microcosms had a larger impact on the communities derived from the e-cigarette users compared to that of the nonusers.

Conclusions: Overall, this limited pilot study suggests that beetroot juice extract supplementation may impact the microbiota of e-cigarette users and adds to contemporary research paving the way for more in-depth studies examining the role of nitrate-rich supplements as prebiotics to promote oral health.

Background: Antibiotics are used in periodontal therapy in selected cases, but therapy is rarely guided by antimicrobial susceptibility testing (AST). Direct AST of the oral microbiota using a combination disk with different antibiotics could provide a new way of AST to guide treatment planning.

Methods: We performed AST of 46 strains of Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum complex, Prevotella species, and Porphyromonas gingivalis, with a combination disk of amoxicillin (AMX) and metronidazole (MET). The AMX-MET was compared to the largest inhibition zone diameter (IZD) obtained with AMX or MET disks, using an ordinary least square linear regression model.

Results: The IZD of the AMX-MET correlated with the AMX for A. actinomycetemcomitans (interception 0.3) and with the MET for Fusobacterium (interceptions -1.25). For Prevotella, the AMX-MET was compared to AMX and MET after 20 and 44 h resulting in a superior correlation after 20 h (interception 0.06 vs 6.61 after 44 h). For P. gingivalis, the AMX-MET was compared to MET after 44 h resulting in an inferior correlation (interception 16.65).

Conclusion: The IZD of AMX-MET was comparable to that of AMX and MET for important periodontal pathogens, which opens for studies on direct AST of oral samples with a mixed microbiota.

Key message: The amoxicillin-metronidazole disk for antimicrobial susceptibility testing results in comparable inhibition zone diameters to that of AMX and MET for important periodontal pathogens.

Objective: Postoperative infection is one of the most common complications in dental procedures. During local anesthesia in dental treatments, the risk of postoperative infections increases if the oral mucosa is infected, the anesthesia injection site is inadequately disinfected, or the injection needle and anesthetic drugs are contaminated. Thus, developing new oral local anesthetics that offer superior anesthesia, enhanced safety, and antimicrobial properties could greatly enhance their clinical value.

Methods: The anesthetic effects and antibacterial properties of articaine derivatives were screened using membrane chromatography techniques, animal experiments, and cellular molecular assays. Safety assessments were conducted on the selected target compounds. Additionally, the antibacterial mechanisms of the compounds were investigated through molecular dynamics simulations and cryo-electron microscopy.

Results: Through the screening of articaine derivatives, a novel local anesthetic, AT-15, was identified, which combines effective anesthetic properties with antibacterial activity. This compound exhibits strong pharmacological activity and high safety. Its antibacterial effect is believed to result from the disruption of bacterial cell membranes and the inhibition of topoisomerase, an enzyme essential for bacterial DNA synthesis.

Conclusion: AT-15 discovered in this study is a promising candidate for further development in clinical settings.

Objectives: Animal studies suggest that periodontopathic bacteria induce gut dysbiosis and related pathology, possibly connecting periodontitis to non-oral diseases. However, the effects on the gut ecosystem in periodontitis patients are not fully understood.

Methods: We conducted a comprehensive analysis of the salivary and gut microbiota using 16S rRNA sequencing in periodontitis patients before and after treatment, comparing them to healthy participants. Serum metabolites were also analyzed.

Results: Periodontitis patients showed high alpha diversity in both salivary and gut microbiota with a strong correlation. Significant differences were also observed in the gut microbiota composition between patients before treatment and healthy participants, irrespective of the ectopic colonization of periodontitis-associated bacteria in the gut. Co-abundance group analysis demonstrated that the gut microbiota of healthy participants was enriched with short-chain fatty acid producers. Changes in the gut microbiota coincided with alterations in the serum metabolite profile. While periodontal therapy improved salivary microbiota, it did not significantly affect gut microbiota.

Conclusions: Gut dysbiosis of periodontitis patients may impact systemic metabolite profiles. Given that periodontal therapy alone did not substantially improve the gut microbiota, adjunctive strategies targeting the gut microbiome may be effective in reducing the risk of periodontitis-associated diseases.

Objective: A heavy infection in a primary molar tooth can impair the enamel formation of the underlying permanent successor. Helicobacter pylori colonizes primarily the stomach, but it has also been detected in oral samples, including in the dental pulp of infected primary teeth. Here, we aim to test if H. pylori can disturb enamel and dentin formation.

Methods: Mandibular molar explants of E18.5 mice were grown for 12 days in media containing 10% of H. pylori cell lysates. The presence and extent of enamel and dentin on the mesial surface of the first molar explants were evaluated from stereomicroscopic photographs and histologically.

Results: The statistical analyses revealed that less enamel was formed in the test (N = 47) than in the control first molars (N = 28, p < 0.001). Most severe disturbances were seen in explants grown in media containing H. pylori cell lysates, which were made from stationary growth-phase cultures, with high optical density. Histological findings showed that dentin mineralization was also impaired.

Conclusion: The results suggest that H. pylori disturbs enamel and dentin development in cultured mouse embryonic molar teeth. This provides new insight into the etiology of enamel disturbances in permanent teeth.

Aim: This study investigated the correlation between tongue coating thickness (TCT), micro-inflammatory state (MIS), and oral microbiome in maintenance hemodialysis (MHD) patients.

Methods: Forty MHD patients (20 thin-tongue coating [BTZ], 20 thick-tongue coating [HTZ]) and 15 healthy controls (DZZ) were enrolled. Blood microinflammatory markers were analyzed in all patients. Saliva samples from 15 HTZ, 15 BTZ, and 15 DZZ underwent 16S rRNA sequencing.

Results: HTZ patients exhibited higher microinflammatory marker levels than BTZ. Oral microbiome species richness in DZZ surpassed that of the MHD groups, with distinct structural differences, particularly between HTZ and DZZ. HTZ showed higher abundances of Actinobacillus, Peptostreptococcus, and Lachnospiraceae NK4A136 group than BTZ. Correlation analysis revealed a positive correlation between the levels of IL-6 and TNF-α and the abundance of Fusobacterium, but a negative correlation with Streptococcus. Additionally, the TNF-α level positively correlated with Campylobacter.

Conclusion: Thick tongue coating in MHD patients is associated with elevated microinflammation and altered oral microbiome, suggesting a link between inflammation and microbial dysbiosis.

Background: The presence of viruses in healthy teeth has not been extensively studied, although some viral traces have been detected in both healthy and diseased dental pulps in previous studies focusing primarily on a single species. The aim of this study is to clarify the persistence of DNA viruses in dental tissues and their impact on tissue composition.

Materials and methods: Here, the prevalence of persistent DNA viruses in intact third molars (n = 17) was assessed via quantitative PCR to detect human parvovirus B19 (B19V), torque teno virus (TTV) and nine human herpesviruses. Also, H&E-stained tissue sections of the samples were analyzed for any potential inflammatory process. RNAscope in-situ hybridization was performed for B19V, TTV and HHV7 subsequently.

Results: Viral DNA of five different viruses was detected in 5 of the 17 samples (29.4%) including B19V (n = 2), TTV (n = 2), HHV7 (n = 2), HCMV (n = 1) or EBV (n = 1) in dental pulps with no signs of cytopathic effect, inflammatory cell accumulations or necrosis. RNAscope in-situ hybridization confirmed the presence of B19V and TTV in non-inflamed pulp tissue.

Conclusions: These findings emphasized that even in the absence of a disease evaluated by histology, dental pulp can harbor DNA viruses and be an anatomical site of virus tropism, suggesting viral persistence rather than direct pathogenic activity.