Journal of Oral Microbiology最新文献

Background: The homeostasis of the subgingival microbiome is crucial for periodontal health, although the dynamics governing its community variation remain insufficiently studied. This study aims to investigate the dynamics of subgingival microbiota reassembly after disruption, focusing on core taxa, functions, and driving forces.

Methods: 339 subgingival plaques in periodontally healthy states were collected before and after ultrasonic cleaning across 12 timepoints for 1 year. All samples underwent full-length 16S rRNA sequencing; 30 were selected for metagenomic sequencing.

Results: Our findings revealed that disturbed subgingival microbiota underwent short-term disruptions but subsequently reverted to baseline, maintaining stability within a year. Homogeneous selection dominated assembly, driving convergent structure under consistent pressure. Such a recovery process was accompanied by key taxa increased sequentially: Pseudomonas fluorescens early, Haemophilus parainfluenzae mid-stage, and Capnocytophaga spp. late. Functionally, reconstruction began with energy metabolism, expanded via biofilm formation and LPS biosynthesis mid-stage, and involved late apoptosis and complex amino acid metabolism. Microbial interactions, including positive regulation from Veillonella HMT 780 to Fusobacterium HMT 248, internally drove community assembly.

Conclusion: Our study clarifies species and functional dynamics during subgingival microbiota reconstruction and maps time-directed networks among stage-specific bacteria, offering a theoretical basis for targeted microbiome regulation.

The oral microbiota is intimately linked to human health and various disease states. With the advent of the Human Microbiome Project, our comprehension of the oral microbiota has substantially improved. This microbial community is not only associated with a range of oral diseases, such as dental caries and periodontal diseases, but also with numerous digestive disorders, as demonstrated by recent clinical studies. Specific bacteria residing in the oral cavity, such as Porphyromonas gingivalis, Fusobacterium species and Streptococcus species, have been shown to translocate to the gastrointestinal tract, thereby establishing a potential connection between the oral and gut microbiota. The transfer and ectopic colonization of oral microbiota within the gastrointestinal tract may contribute to both the onset and exacerbation of gastrointestinal diseases. Following the principles of dysregulation characteristics, mechanism research and innovative treatment, this paper systematically reviews the association between the oral microbiota and various digestive system diseases. This paper explores how specific oral microbiota drive digestive system diseases mechanisms and evaluates treatments including probiotics, prebiotics, fecal microbiota transplantation, and targeted antimicrobial therapies. By clarifying the oral-gut microbiota-disease link, it highlights oral microbiota monitoring as a promising tool for early detection, diagnosis, and therapy.

Background: Dental caries is a widespread global health issue strongly associated with Streptococcus mutans. Bacteriophage-derived lytic enzymes such as ClyR hold considerable promise as antibacterial potential, but the molecular mechanisms underlying their activity against S. mutans remain unclear.

Objective: This study aimed to determine the role of water-insoluble exopolysaccharides (EPS) in mediating the antibacterial activity of ClyR against S. mutans.

Design: We compared the antibacterial effects of ClyR on S. mutans UA159 and its ΔgtfB mutant, which is characterized by reduced synthesis of water-insoluble EPS. Biofilm architecture and susceptibility were assessed using scanning electron microscopy, confocal laser scanning microscopy, and biomass quantification. Adsorption assays were conducted to evaluate the interaction between ClyR and water-insoluble EPS.

Results: The ΔgtfB mutant exhibited significantly higher resistance to ClyR than S. mutans UA159, with reduced biofilm disruption and bacterial loss after treatment. In vitro assays confirmed that water-insoluble EPS specifically adsorbed ClyR, with binding localized to its catalytic PlyCAC domain.

Conclusions: Water-insoluble EPS synthesized by S. mutans glucosyltransferases plays a critical role in modulating bacterial susceptibility to ClyR. These findings reveal a novel mechanism underlying bacteriophage lysin activity and highlight EPS as a potential target for enhancing ClyR efficacy against cariogenic biofilms.

Background/purpose: Candidiasis is the most common oral fungal infection. Several medications have been introduced to manage this infection. This study investigated the antifungal effect of caffeic acid and nano-caffeic acid.

Materials and methods: The size and particle dispersion index (PDI) of caffeic acid-containing niosome vesicles were measured after their production. The zeta potential was measured using a Zetasizer Nano ZS, and the amount of nano-caffeic acid released from the vesicles was measured. Candida isolates were cultured in Malt Extract Agar medium. Nystatin, fluconazole, caffeic acid and nano-caffeic acid were studied according to the Clinical and Laboratory Standards Institute (CLSI) protocol (M27-A3/S4), a broth microdilution test was performed, and the minimum inhibitory concentration (MIC) was determined. The data were analyzed using the Mann‒Whitney and Kruskal‒Wallis tests.

Results: The optimal formulation had 100 mg Tween 60, 100 mg Span 60, 200 mg cholesterol, a size of 271.83 ± 3.11 nm, a PDI of 0.21 ± 0.02, a zeta potential of 5.58 ± 0.47 mV and an encapsulation efficiency (EE%) of 42.34 ± 4.34%. The size, absolute zeta potential and EE% increased significantly with increasing cholesterol content from zero to 200  mg (P < 0.05). Caffeic acid, nano-caffeic acid, carrier, fluconazole and nystatin had the lowest to highest antifungal activity, respectively.

Conclusion: According to the MIC₅₀ and MIC₉₀ values, nystatin, fluconazole, carrier, nano-caffeic acid and caffeic acid had the highest to lowest inhibitory efficiency against Candida species, respectively.

Background: The study aims to investigate Streptococcus cristatus, an oral commensal bacterium, as a probiotic for dental caries prevention by modulating the oral microbiome.

Methods: Saliva from four healthy donors was used to establish 24-h microcosm biofilms in an in vitro 96-well peg model. The preformed biofilms were then exposed to biofilm medium containing 0.2% sucrose (BM), with or without S. cristatus. They were grown for 48 h under two conditions: a constant pH-neutral regime (BM supplemented with 76 mM K₂HPO₄ and 15 mM KH₂PO₄, pH 7.0) or cariogenic pH-cycling regime (8 h pH-neutral and 16 h in BM containing 100 mM acetic acid, pH 5.5). Phosphate and acetate buffers were used to control pH. After 72 h, the biofilms were analyzed for biomass, lactic acid production, hydrogen peroxide (HP) concentrations, and microbial composition via 16S rRNA gene sequencing.

Results: S. cristatus successfully integrated into 24-h preformed microcosm biofilms derived from individual saliva. Under pH-neutral conditions, it reduced biofilm biomass and lactate production while increasing hydrogen peroxide (HP) generation in a donor-dependent manner. Conversely, under cariogenic pH-cycling conditions, these inhibitory effects on biomass and lactate production were consistent across all donors, although HP was undetectable. Microbiome analysis revealed that S. cristatus increased species richness and mitigated the compositional shifts caused by pH-cycling. This was achieved by inhibiting Streptococcus salivarius/vestibularis across all donors, while promoting Streptococcus mitis group and Streptococcus anginosus in a donor-dependent manner.

Conclusions: S. cristatus represents a promising microbiome modulator with the potential to substantially mitigate the cariogenicity of oral microcosms.

Background: Porphyromonas gingivalis is a predominant pathogen in periodontitis and is closely associated with the progression of chronic obstructive pulmonary disease (COPD).

Objective: This case report aims to describe a case of sepsis caused by P. gingivalis in a patient with COPD and a history of dental pain, highlighting the diagnostic challenges and clinical implications.

Design: This single case report was based on clinical data collected from medical records, with the pathogen identified from blood cultures by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). A comparative analysis was performed between the present case and previously reported cases of P. gingivalis bacteremia or sepsis based on a literature review. The patient was discharged after his general condition improved as a result of the potentially effective antimicrobial agents and anti-infective treatments through literature review.

Results: A 73-year-old man with COPD and a prolonged history of dental pain presented with a 30-year history of recurrent cough, expectoration, and dyspnoea, with symptoms exacerbating over the past 3 d and the recent onset of high fever for 1 d. Clinical evaluation revealed sepsis with rapid progression to septic shock. Blood cultures confirmed the presence of P. gingivalis.

Conclusions: This case highlights the need to consider anaerobes like P. gingivalis in septic patients with poor oral health, especially for patients with dental pain or periodontitis, and highlights the diagnostic challenges associated with slow-growing pathogens.

Background/objective: Oral squamous cell carcinoma (OSCC) in patients without tobacco, alcohol, or betel-quid habits is poorly understood and difficult to detect early. This study aimed to identify microbial biomarkers specific to this habit-free population using third-generation sequencing (TGS).

Patients/materials and methods: Twenty-seven habit-free OSCC patients were recruited at National Taiwan University Hospital (NTUH). Paired tumor and adjacent normal tissues were collected with informed consent and NTUH Research Ethics Committee approval (IRB 201902080RINC, 201304078RIND). Full-length 16S rRNA sequencing (PacBio Sequel IIe) was processed with DADA2 and SILVA. Biomarkers were identified using sparse partial least squares discriminant analysis (sPLS-DA) and random forest with cross-validation, and validated against three public OSCC cohorts.

Results: A three-species panel-Eikenella corrodens, Slackia exigua, and Eggerthia catenaformis-discriminated tumor from normal tissues (AUC = 0.905 training; 0.733 testing). Functional and network analyses showed tumor-enriched taxa forming pro-inflammatory clusters linked to lipid and glutamine metabolism, while commensals correlated with homeostatic pathways. Cross-cohort comparison confirmed this panel's specificity to habit-free OSCC.

Conclusions: Using TGS, we revealed distinct microbial signatures in habit-free OSCC that may aid early diagnosis and underscore the role of microbiome-host interactions in carcinogenesis.

Introduction: Porphyromonas gingivalis, a Gram-negative anaerobe, is a key contributor to periodontal disease. Emerging evidence suggests a role for the P. gingivalis CRISPR-Cas system in disease progression, although the specific roles of its components remain unclear.

Objectives: Here we investigate the role of cas7, a Class 1 type I-B CRISPR-Cas system component, in P. gingivalis physiology and host interaction.

Methods: We compared P. gingivalis wild-type and ∆cas7 strains for growth, biofilm formation, oxidative stress resistance, and hemagglutination. Host interactions were assessed using THP-1 macrophage-like cells to evaluate intracellular survival and cytokine response. Dual RNA-seq enabled host and microbe transcriptomic profiling during cellular infection, and Galleria mellonella was used to assess virulence.

Results: The ∆cas7 mutant showed similar planktonic growth and biofilm formation compared to wild-type but was more sensitive to oxidative stress and had reduced hemagglutination. Although intracellular survival was unaffected, ∆cas7 altered the host cytokine production profile. Transcriptomic analysis revealed differential gene expression linked to oxidative stress and disease progression. In vivo, ∆cas7 infection led to a trend of increased larval mortality.

Conclusion: These findings reveal a previously unrecognized role for cas7 in modulating P. gingivalis virulence, offering new insights into CRISPR-Cas system functions in bacterial pathogenesis.

Background: Candida albicans (C. albicans) is closely associated with cancer. Whether C. albicanscan directly induce the occurrence of oral cancer remains undetermined.

Objective: This study aimed to explore the carcinogenic potential of C. albicans in oral cancer.

Methods: Transcriptome sequencing (mRNAseq) and whole exome sequencing (WES) were performed to reveal the effects of long-term C. albicans stimulation on oral mucosa in mouse models. 4-nitroquinoline-1-oxide (4NQO), a mutagenic substance that mimics tobacco, was used to examine the combined role of tobacco smoking and C. albicans in oral carcinogenesis. Additionally, the somatic mutation landscape of chronic hyperplastic candidiasis (CHC)-a variant of oral candidiasis typically presenting with dysplasia-was characterized in biopsy tissues.

Results: Long-term C. albicans stimulation didn't directly induce oral cancer in mouse models but significantly upregulated the expression of genes related to cell proliferation and cancer development in the oral epithelium (e.g. Mki67, Kif11, Ccna2, Ckap2, Fos, Ccnb1; P < 0.05). Analysis of somatic mutations in CHC revealed that Candida and smoking might co-contribute to this type of precancerous lesion. Furthermore, C. albicans stimulation activated signaling pathways involved in inflammation and immune response, and promoted cancer formation in mice pre-treated with 4NQO.

Conclusion: C. albicans alone rarely induces carcinogenesis directly but can accelerate the malignant transformation of oral mucosa when combined with smoking.

Introduction: Infant formulas with reduced iron levels and lactoferrin (Lf) supplementation might mimic the beneficial effects of breast milk on the oral microbiome. This study aimed to investigate the impact of a bovine Lf-supplemented and iron-reduced formula on the oral microbiota in infants at 4, 6 and 12 months.

Methods: In a double-blind controlled trial, 6-week-old formula-fed infants were randomized to receive either a formula with reduced iron levels (2 mg/L) and Lf supplementation (1 g/L) (n = 72), the same formula without Lf (n = 72), or a standard formula (8 mg iron/L) (n = 36). A breast-fed reference group (n = 72) was also included. The oral microbiota was analyzed at 4 (n = 244), 6 (n = 216) and 12 (n = 229) months of age using the Oxford Nanopore Technology of the 16S rRNA gene annotation (eHOMD database).

Results: Neither the within- or between-group diversities nor overall microbiota pattern assessment revealed any statistically significant differences in microbiota composition between the formula groups. However, single species were significantly associated with specific formula-fed groups. At 6 months, breast-fed infants exhibited significantly lower species richness and distinct microbiota composition compared to the formula-fed groups.

Conclusions: The effects of reduced iron levels and lactoferrin supplementation of infant formula on the oral microbiome were inconclusive.