Journal of Oral Microbiology最新文献

Background: Chlorhexidine (CHX) is widely used in oral care for its broad-spectrum antimicrobial activity but can cause significant side effects. Sodium DNA has emerged as a potential adjunct capable of modulating cellular responses.

Aim: This study assessed whether sodium DNA enhances the antibacterial and antibiofilm activity of 0.20% and 0.12% CHX mouthwashes against Streptococcus mutans and Escherichia coli, and evaluated their effects on the viability and phagocytic activity of Dictyostelium discoideum, a model for mammalian phagocytes.

Results: All CHX-containing mouthwashes were bactericidal against S.mutans, regardless of sodium DNA, whereas CHX-only formulations were more effective against E.coli in time-kill assays. All formulations inhibited biofilm formation at 50-0.01%. In S. mutans, early biofilms were strongly inhibited (50-0.39%), whereas mature biofilms were less affected. In E. coli, sodium DNA enhanced inhibition of both biofilm formation (50-1.56%) and mature biofilms (50-3.12%). The 0.12% CHX-sodium DNA formulation most effectively modulated D.discoideum viability and phagocytic activity, and metabolomics showed that sodium DNA reduced CHX-induced metabolic stress.

Conclusions: This study integrates antimicrobial, antibiofilm, cellular, and metabolomic analyses to assess CHX with sodium DNA. Sodium DNA reduces CHX-induced cytotoxicity and metabolic stress while maintaining antimicrobial activity, offering insights for optimizing oral hygiene formulations through combined microbial and host-cell evaluation.

Background: The oral cavity is an important yet understudied reservoir of antimicrobial resistance genes (ARGs), potentially shaped by geographic variation in antibiotic usage.

Objective: To compare the oral resistomes of healthy adults from Thailand and Norway, two countries with contrasting antimicrobial use practices, using shotgun metagenomic sequencing.

Design: Stimulated saliva samples were collected from healthy adults in Thailand (n = 43) and Norway (n = 50). ARGs were identified with AMRPlusPlus against the MEGARes database, and microbial taxonomy was profiled with KrakenUniq. Diversity metrics, ordination, and clustering analyses assessed resistome and microbiome structures.

Results: Thai samples exhibited significantly greater ARG richness, evenness, and diversity (p < 0.001), driven by higher abundances of multi-biocide, nucleoside, and copper resistance genes. Norwegian samples were enriched in aminoglycoside, sulfonamide, and quaternary ammonium compound resistance genes. Both cohorts shared core oral genera, but Thai samples showed greater taxonomic richness without differences in overall microbiome diversity. Non-metric multidimensional scaling and PERMANOVA revealed stronger geographic separation for resistomes (R² = 0.639) than microbiomes (R² = 0.382). Co-occurrence networks highlighted structured associations between ARG groups and bacterial genera, suggesting ecological influences beyond taxonomic composition.

Conclusions: These results reveal distinct geographic signatures in the oral resistome that are not fully explained by microbiome structure, reflecting the influence of local ecological and societal factors, including antimicrobial exposure. The findings highlight the oral cavity as a dynamic ARG reservoir and support its inclusion in regional antimicrobial resistance surveillance to inform public health strategies.

Background: The pathogenesis of oral squamous cell carcinoma (OSCC) in never-smoking females remains poorly understood, as these patients lack traditional risk factors. This subgroup accounts for an increasing proportion of OSCC cases and may exhibit distinct tumor biology. Here, we investigated the association between the alterations in the salivary microbiome and OSCC in never-smoking female patients.

Materials and methods: Saliva samples from 72 never-smoking female patients with OSCC and 494 never-smoking healthy female controls were analyzed using 16S rRNA gene sequencing. Microbial community structure and function were compared using statistical analyses, machine learning algorithms, and pathway prediction with PICRUSt2.

Results: Patients with OSCC exhibited significantly different microbial diversity and composition compared to controls. The genera Rhodococcus, Slackia, Lactobacillus, and Enterobacterales_g were enriched in the OSCC group, whereas Corynebacterium was more abundant in the Control group. These taxa were associated with oncogenic pathways, including PI3K-Akt signaling and nicotinate/nicotinamide metabolism. Functional inference also indicated enrichment of cancer-related orthologs such as LKB1, NFKB1, ITGAV, and TRAF4.

Conclusions: Salivary microbiome alterations, both taxonomic and functional, are associated with OSCC in never-smoking females. These findings suggest a potential microbial contribution to carcinogenesis in this unique patient population and offer novel insights into disease mechanisms.

Background: Molecular identification of dental caries microbes is advancing rapidly, yet sampling methods remain outdated and imprecise.

Objective: To refine microbe sample harvesting and preserve taxa pre-harvest spatial positions relative to lesion pulpal depth.

Methods: Refinements included a sterile zone surrounding the dissection site and emphasize asepsis, surgical microscope magnification and lighting, and micro-surgical techniques. Retention of taxa pre-harvest spatial positions relative to lesion pulpal depth used shallow-layered dissection (mean 6 mg/layer, SD 2.65 mg), where each layer became a separate sample for molecular identification before sequential reassembly in a layered lesion diagram. To evaluate the method's robustness, 14 lesions varying in severity and type from private dental practices were dissected using the method (7 pit and fissure and 7 facial lesions; 4 untreated, 3 treated).

Results: Pre-harvest taxa detail, not possible previously, showed taxa location, abundance and diversity relative to lesion pulpal depth, as well as absolute abundance per milligram and taxa transitions and fluctuations from superficial through the deepest dissected layers. The method provides these data regardless of lesion type, stage, or complexity, whether untreated or treated.

Conclusions: This method provides new details and perspectives on dental caries taxa that could help develop diagnostic instruments and treatments to halt dental caries progression.

Background: Tonsillar hypertrophy (TH) and adenotonsillar hypertrophy (ATH) are primary risk factors for paediatric obstructive sleep apnoea (OSA), but their salivary microbiota differ.

Objective: This study aimed to investigate whether the tonsillar surface and core microbiota resemble the salivary microbiota, and whether these microbial profiles are influenced by adenoid hypertrophy and related clinical factors.

Design: Forty-nine children undergoing tonsillectomy were enrolled, including 21 children with TH and 28 with ATH. Saliva and tonsillar surface swabs were collected preoperatively, and core tissues were obtained intraoperatively. Microbiota were profiled via 16S rRNA sequencing, compared across sites and groups, and correlated with preoperative clinical indicators.

Results: The tonsillar core microbiota was relatively stable across all children, whereas the surface and salivary microbiota shifted with adenoid hypertrophy. Prevotella, Neisseria, Veillonella, Alloprevotella, Lancefieldella and Haemophilus were consistently more abundant on the tonsillar surface compared to the core. Gemella was uniquely enriched on the surface and positively correlated with the obstructive apnoea-hypopnoea index and red cell distribution width in the TH group.

Conclusions: This study reveals distinct microbial profiles between the tonsillar surface and core. In TH, surface microbiota was associated with OSA severity and haematological indicators, suggesting potential relevance that warrants further investigation.

Background: Smoking increases mortality risk and alters the oral microbiome, but its mediating role in the smoking-survival relationship remains unclear. This study examined whether oral microbiome diversity mediates the association between smoking and all-cause mortality.

Methods: We included 8,223 participants from the National Health and Nutrition Examination Survey with linked mortality data through 2019. Oral microbiome diversity was assessed using alpha and beta diversity metrics. Associations between smoking, diversity, and mortality were assessed using Weibull Accelerated Failure Time models. Multivariable linear regression evaluated the relationship between smoking and oral microbiome diversity. Mediation analysis estimated the Natural Direct Effect (NDE) and Natural Indirect Effect (NIE). Sensitivity analyses assessed effect heterogeneity.

Results: Among participants, 429 were deceased. Current smoking was associated with a 42.3% shorter survival time (TR = 0.577). Greater ln-transformed observed Operational Taxonomic Units (OTU) richness was associated with 33.2% longer survival time (TR = 1.332). Smoking was associated with survival time through NIE = 1.013 (95% CI: 1.003, 1.033) and NDE = 0.577 (95% CI: 0.474, 0.697). Sensitivity analyses supported the findings.

Discussion: Oral microbiome diversity partially mediated the association between smoking and mortality. Although smoking shortened survival, its effect on increasing OTU richness modestly suppressed this risk. These results highlight a complex microbial pathway and support further investigation into species-level mechanisms and potential microbiome-targeted interventions.

Background: Porphyromonas gingivalis, a key pathogen in chronic periodontitis, produces heterogeneous lipopolysaccharides (LPS) that are weakly recognized by Toll-like receptor 4 (TLR4). Human cells detect cytosolic LPS via caspase-4 (CASP4); however, whether P. gingivalis LPS (PgLPS) can directly activate CASP4 remains unclear. This study aimed to investigate the CASP4-activating properties of purified PgLPS.

Methods: Standard-grade (ST) and ultrapure-grade (UP) purified PgLPS were tested for CASP4 activation using recombinant CASP4 in fluorogenic and IL-18 assays. PgLPS-CASP4 interactions were examined by pull-down. In HSC-2 cells, IL-18 maturation, gasdermin D cleavage, pyroptosis, and dependence on CASP4 or TLR4 were assessed after cytosolic LPS delivery. Guanylate-binding protein-1 (GBP1) involvement was evaluated by siRNA knockdown. Effects of outer membrane vesicles (OMVs) were also tested.

Results: ST-PgLPS directly activated recombinant CASP4, while UP-PgLPS did not. Intracellular delivery of ST-PgLPS induced weak pyroptosis, while UP-PgLPS had no effect. Responses were abrogated by CASP4 inhibition but not by TLR4 inhibition. IFN-γ priming enhanced responses: ST-PgLPS induced moderate activation, whereas UP-PgLPS triggered robust, GBP1-dependent activation. OMVs activated CASP4 in IFN-γ-primed cells.

Conclusion: CASP4 activation depends on PgLPS purity and host cell priming. GBP1 contributes to PgLPS sensing, and OMVs serve as vehicles for PgLPS delivery to the cytosol.

Background: Aging is characterized by progressive physiological decline and increased susceptibility to age-related diseases. The oral microbiome, a complex community of microorganisms, has been increasingly recognized as a potential key player in the aging process.

Objective: This review aims to explore and summarize the relationship between the oral microbiome and aging, with a specific focus on contrasting microbial changes in healthy and unhealthy aging populations.

Design: We conducted a comprehensive review of the current literature to synthesize evidence on oral microbiome shifts during aging, the influencing factors, associations with age-related conditions, and potential interventions.

Results: Evidence indicates that the composition of the oral microbiome changes with age, although findings on diversity are inconsistent, with reports of both increases and decreases in older adults. These shifts are influenced by factors such as diet, oral hygiene, and immune function. Unhealthy aging, including conditions like frailty, neurodegenerative diseases, and sarcopenia, is associated with distinct oral dysbiosis. Potential mechanisms linking the oral microbiome to aging include chronic inflammation and immunosenescence. Interventions targeting the oral microbiome, such as probiotics and dietary modifications, show promise in promoting healthspan.

Conclusions: The oral microbiome is significantly altered during aging and is implicated in age-related health status. It represents a promising target for strategies aimed at promoting healthy aging. Future research should prioritize elucidating the functional mechanisms of oral microbiota and developing targeted microbiome-based interventions.

Objective: This longitudinal study aimed to characterize the spatial and temporal dynamics of oral microbiome colonization on removable partial dentures (RPDs) and corresponding dental surfaces at species-level resolution, to elucidate ecological succession patterns and identify potential pathogenic colonizers.

Methods: We conducted a longitudinal study of 10 participants requiring RPDs. Plaque samples were collected from four sites at five time points. The microbial communities were profiled using PacBio full-length 16S rRNA sequencing, enabling high accuracy taxonomic assignment to the species level. Bioinformatic analyses included alpha/beta diversity, LEfSe, and PICRUSt2 functional prediction.

Results: Significant differences in microbial composition were observed between RPD and dental plaques, despite similar alpha diversity. Temporal analysis revealed a progressive decrease in RPD plaque diversity. Notably, the potential respiratory pathogen Klebsiella pneumoniae was detected in early RPD biofilms. A three-stage ecological succession model for RPD biofilm was proposed, initiating with acidogenic pioneers, followed by functional amplification of taxa involved in extracellular polysaccharide production, and culminating in a stable, acid-tolerant community.

Conclusion: This study provides a species-level understanding of microbiome changes associated with RPDs, confirms differences between RPD plaque and dental plaque, proposes a succession model for RPD-associated bacteria, and determines key turning points and potential pathogens.

Background: The host microbiome is increasingly recognized as a key modulator of brain function and disease progression, yet the role of the oral microbiome in patients with prolonged disorders of consciousness remains underexplored.

Methods: This study characterized oral microbiota differences among pDoC patients (n = 89) in the vegetative state (VS), the minimally conscious state (MCS), and emerging from the MCS (EMCS), with a particular focus on the impact of antibiotic use. We used 16S ribosomal RNA sequencing to profile oral microbiota in patients with different levels of consciousness.

Results: β-diversity was significantly reduced in the VS group compared to the EMCS group. Differential abundance analysis identified five taxa (i.e., species Streptococcus danieliae, species Corynebacterium durum, family Lachnospiraceae, species Phocaeicola abscessus, and species Campylobacter showae) that exhibited significant differences between VS and EMCS, suggesting they were potentially involved in regulating oral microbial dysbiosis and brain-microbiome interactions. Antibiotic treatment induced pronounced microbial shifts in the VS group, while no such effect was observed in the MCS or EMCS groups. Prognostic models built using differential and dominant microbiota panels demonstrated strong predictive performance, achieving areas under the curve of 0.820 and 0.920, respectively.

Conclusions: These findings highlight oral microbiome alterations in pDoC and their potential relevance to disease progression, emphasizing the importance of microbiome-informed clinical strategies.